Animation Rutherford Experiment Nuclear Atoms Questions

Homework 2 Chapter 3Due: 11:59pm on Wednesday, September 21, 2022
To understand how points are awarded, read the Grading Policy for this assignment.
Exercise 3.34 with eText link
MISSED THIS? Watch KCV 3.3; Read Section 3.4. You can click on the Review link to access the section in your eText.
Part A
Classify each of the following mixtures as homogeneous or heterogeneous.
Drag the appropriate items to their respective bins.
ANSWER:
Reset
wine
water and gasoline
homogeneous
baby oil
Help
chocolate chip cookie
heterogeneous
Exercise 3.29
Part A
The following equation can be used to convert Fahrenheit temperature to Celsius temperature.
(F − 32)
C =
1.8
Use algebra to change the equation to convert Celsius temperature to Fahrenheit temperature.
Express your answer in terms of C .
ANSWER:
F
=
Exercise 3.22
Part A
What is an exothermic reaction? Which has greater energy in an exothermic reaction, the reactants or the products?
Match the words in the left column to the appropriate blanks in the sentences on the right.
ANSWER:
Reset
releases
An exothermic reaction is one that
reactants
have more energy than the
energy
Help
the surroundings. The
in an exothermic reaction.
into
absorbs
products
from
Exercise 3.118
Global warming refers to the rise in average global temperature due to the increased concentration of certain gases, called greenhouse gases, in our
atmosphere. Earth’s oceans, because of their high heat capacity, can absorb heat and therefore act to slow down global warming.
Earth’s oceans moderate temperatures by absorbing heat during warm periods.
Part A
How much heat would be required to warm Earth’s oceans by 1.0 ∘ C? Assume that the volume of water in Earth’s oceans is 135 × 10 7 km3 and that the
density of seawater is 1.03 g/cm3 . Also assume that the heat capacity of seawater is the same as that of water.
Express your answer in joules to two significant figures.
ANSWER:
q
=
J
Chapter 3 Question 7 – Multiple Choice
Part A
Which among the following statements is false?
ANSWER:
A gas has neither definite volume nor definite shape.
A solid has a definite shape and a definite volume.
Both solids and liquids are incompressible while gases are compressible.
A liquid has a definite volume; but it has no definite shape.
none of the above
Chapter 3 Question 16 – Multiple Choice
Part A
Which of the following statements is FALSE?
ANSWER:
A mixture may be either homogeneous or heterogeneous.
A pure substance may either be an element or a compound.
Mixtures may be composed of two or more elements, two or more compounds, or a combination of both.
Matter may be a pure substance or it may be a mixture.
All of the above statements are true.
Conceptual Checkpoint 3.2 – Enhanced – with Feedback
Part A
Which of the substances depicted here is a pure substance?
ANSWER:
Exercise 3.32 – Enhanced – with Feedback
MISSED THIS? Watch KCV 3.3; Read Section 3.4. You can click on the Review link to access the section in your eText.
Part A
Classify each of the following pure substances as an element or a compound.
Drag the appropriate items to their respective bins.
ANSWER:
Reset
carbon
baking soda (sodium bicarbonate)
Element
nickel
Compound
Chapter 3 Question 22 – Multiple Choice
Part A
All of the following can be considered physical properties EXCEPT:
ANSWER:
color.
density.
flammability.
boiling point.
taste.
Chapter 3 Question 23 – Multiple Choice
Part A
Which of the following items is a physical property?
ANSWER:
the corrosive action of acid rain on granite
the combustion of gasoline
the odor of spearmint gum
the tarnishing of a copper statue
none of the above
Exercise 3.40 – Enhanced – with Feedback
gold
Help
MISSED THIS? Read Section 3.5. You can click on the Review link to access the section in your eText.
Part A
The following list contains several properties of ozone (a pollutant in the lower atmosphere but part of a protective shield against UV light in the upper
atmosphere). Which are physical and which are chemical?
Drag the appropriate items to their respective bins.
ANSWER:
Reset
decomposes on exposure to
ultraviolet light
gas at room temperature
pungent odor
Physical
Help
very reactive
bluish color
Chemical
Exercise 3.105
Evaporating sweat cools the body because evaporation is endothermic and absorbs 2.44 kJ per gram of water evaporated.
Part A
Estimate the mass of water that must evaporate from the skin to cool a body by 0.90 ∘ C, if the mass of the body is 90 kg and its heat capacity is 4.0
∘
J/g C. (Assume that the heat transfer is 100 % efficient.)
Express your answer using two significant figures.
ANSWER:
m
=
g
Properties and Changes of Matter
Matter has both physical and chemical properties and can undergo physical or chemical changes. Physical properties are those that a substance displays
without changing its composition, whereas chemical properties are evident only during a chemical change (also called a chemical reaction). In contrast, when a
substance undergoes a physical change, it may change appearance, but not its composition.
Part A
Classify each of the changes as a physical change or a chemical change.
Drag each item to the appropriate bin.
You did not open hints for this part.
ANSWER:
Reset
tearing aluminum foil
frying a fish
freezing of water
bleaching hair
slicing a banana
carving wood
Help
burning wood
oxidizing of mercury (Hg)
Physical change
Chemical change
Part B
Classify each of the properties as a physical property or a chemical property.
Drag each item to the appropriate bin.
You did not open hints for this part.
ANSWER:
Reset
the reactivity of copper with oxygen
the color of copper wire
the flammability of ethanol
the luster of platinum jewelry
Physical property
Conceptual Checkpoint 3.3 – Enhanced – with Feedback
Part A
In this figure, liquid water is vaporizing into steam.
the melting point of butter
the explosiveness of fireworks
Chemical property
the smell of ginger
Help
Which diagram best represents the molecules in the steam?
ANSWER:
Exercise 3.57
MISSED THIS? Watch IWE 3.5; Read Section 3.8. You can click on the Review link to access the section in your eText.
An energy bill indicates that the customer used 1341 kWh in July. 1 kWh = 3.60 × 10 6 J.
Part A
How many joules did the customer use?
Express your answer in joules to three significant figures.
ANSWER:
Energy =
± Law of Conservation of Mass
J
Matter is neither created nor destroyed in a chemical reaction. Thus, the mass of the products of a chemical reaction must be equal to the mass of the starting
materials. Formally, this concept is called the law of conservation of mass.
Part A
A sample of sodium reacts completely with 0.355 kg of chlorine, forming 585 g of sodium chloride. What mass of sodium reacted?
Express your answer to three significant figures and include the appropriate units.
You did not open hints for this part.
ANSWER:
Part B
When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 18.0 g of carbon were burned in the presence of 61.7 g of oxygen, 13.7 g
of oxygen remained unreacted. What mass of carbon dioxide was produced?
Express your answer to one decimal place and include the appropriate units.
You did not open hints for this part.
ANSWER:
Energy Conversions
Learning Goal:
To practice converting between different units of energy.
Duncan is a college student studying for a chemistry exam this evening. He also plans to go swimming at the school gym and have a dinner of ramen noodles.
While the water for the ramen is heating, it absorbs energy as it gets hot. Later, while swimming, Duncan uses the potential energy in the food he has
consumed.
The following conversion factors may be useful in this problem:
1 cal
= 4.184 J
1 kJ
=
1000 J
Part A
Duncan takes a break from studying and goes to the gym to swim laps. If swimming burns 6.45×105 cal per hour, how many kilojoules does swimming
burn in that same amount of time?
In other words, convert 6.45×105 cal to kilojoules.
Express your answer numerically in kilojoules.
You did not open hints for this part.
ANSWER:
6.45×105 cal =
kJ
Part B Complete previous part(s)
Instructors: View all hidden parts
Interactive Worked Example: Exothermic and Endothermic Processes
First, launch this video. During the video, you’ll be asked a conceptual question about the example. After watching the video, answer the related questions at
the right. You can watch the video again at any point.
Part A
Choose the correct expression.
ANSWER:
The process of water freezing into ice is exothermic and natural gas burning is endothermic.
Both water freezing into ice and natural gas burning are exothermic processes.
The process of water freezing into ice is endothermic and natural gas burning is exothermic.
Both water freezing into ice and natural gas burning are endothermic processes.
Self Assessment 3.4 – Enhanced – with Feedback
MISSED THIS? Watch KCV 3.9, IWE 3.6; Read Section 3.9. You can click on the Review link to access the section in your eText.
Part A
Which process is endothermic?
ANSWER:
The melting of ice in soft drink
The burning of natural gas in a stove
The metabolism of fat by your body
None of the above
Exercise 3.72 – Enhanced – with Feedback
MISSED THIS? Watch IWE 3.9; Read Section 3.10. You can click on the Review link to access the section in your eText.
The coldest temperature ever recorded in Iowa was − 47 ∘ F on February 3, 1998.
Part A
Convert this temperature to degrees Celsius.
Express your answer to two significant figures and include the appropriate units.
ANSWER:
Part B
Convert this temperature to kelvins.
Express your answer to three significant figures and include the appropriate units.
ANSWER:
± Temperature Conversion
Learning Goal:
To express temperatures using the Fahrenheit, Celsius, and Kelvin scales.
Temperature is commonly measured in units of degrees Fahrenheit (∘ F), degrees Celsius (∘ C), or kelvins (K ). The most familiar temperature scale in the
United States is the Fahrenheit scale, in which water freezes at 32 ∘ F and water boils at 212 ∘ F . The scale often used by scientists is the Celsius scale, in
which water freezes at 0 ∘ C and boils at 100 ∘ C . A third temperature scale, called the Kelvin scale, avoids negative temperatures by assigning 0 K to the
coldest temperature possible, absolute zero.
Use the following equations to convert between these temperature scales:
TC =
(TF −32)
1.8
TK = TC + 273.15
where TF is the temperature in degrees Fahrenheit, TC is the temperature in degrees Celsius, and TK is the temperature in kelvins.
Part A
Convert 21.0 ∘ C to degrees Fahrenheit.
Express your answer numerically in degrees Fahrenheit.
You did not open hints for this part.
ANSWER:
∘
F
Part B
Becky is going to take her dog for walk in the park, but before she leaves, she watches the weather report. According to the weather report, it is 82.0 ∘ F
outside. What is the outside temperature in kelvins?
Express your answer numerically in kelvins.
You did not open hints for this part.
ANSWER:
K
Part C Complete previous part(s)
Instructors: View all hidden parts
Interactive Worked Example 3.10: Relating Heat Energy to Temperature Changes
First launch this video. During the video, you’ll be asked a conceptual question about the example. After watching the video, answer the related questions at the
right. You can watch the video again at any point.
Part A
You find a 1979 copper penny (and note that pre-1982 pennies are pure copper) in the snow and pick it up. How much heat does the penny absorb as it
warms from the temperature of the snow, −5.0 ∘ C to the temperature of your body, 37 ∘ C ? Assume the penny is pure copper and has a mass of 3.10 g .
(The specific heat capacity of copper is 0.385 J/(g ⋅ ∘ C) .)
Express your answer in joules to one decimal place.
ANSWER:
heat absorbed by the penny =
J
Part B
The temperature of a lead fishing weight rises from 26 ∘ C to 38 ∘ C as it absorbs 11.3 J of heat. What is the mass of the fishing weight in grams? (The
specific heat capacity of lead is 0.128 J/(g ⋅ ∘ C) .)
Express your answer in grams to two significant figures.
ANSWER:
mass of the fishing weight =
g
Part C
What is the temperature change in 355 mL of water upon absorption of 34 kJ of heat? (The specific heat capacity of water is 4.184 J/(g ⋅ ∘ C) .)
Express your answer in degrees Celsius to two significant figures.
ANSWER:
the temperature change of the water =
∘
C
Part D
Calculate the amount of heat required to raise the temperature of a 65-g sample of water from 32 ∘ C to 65 ∘ C. (The specific heat capacity of water is
4.184 J/(g ⋅ ∘ C) .)
Express your answer in joules.
ANSWER:
amount of heat =
J
Chapter 3 Question 9 – Algorithmic
Part A
Given the table of specific heat values below, what is the identity of a 91.9 g metal sample that increases by 8.5∘ C when 100.0 J of energy is absorbed?
Element Specific Heat(J/g∘ C)
Au
0.128
Ag
0.235
Cu
0.385
Fe
0.449
Al
0.903
ANSWER:
Ag
Au
Fe
Cu
none of the above
Exercise 3.60 – Enhanced – with Feedback
MISSED THIS? Watch IWE 3.5; Read Section 3.8. You can click on the Review link to access the section in your eText.
Part A
How many joules of nutritional energy are in a bag of chips whose label reads 246 Cal?
ANSWER:
E
=
J
Part B
If 1 lb of fat is stored by the body for each 14.6 × 10 3 kJ of excess nutritional energy consumed, how many bags of chips contain enough nutritional
energy to result in 1 lb of body fat?
ANSWER:
N
=
bags
Score Summary:
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Homework 3 Chapter 4
Due: 11:59pm on Wednesday, September 28, 2022
To understand how points are awarded, read the Grading Policy for this assignment.
Chapter 4 Question 1 – Multiple Choice
Part A
Which of the following statements about atoms is FALSE?
ANSWER:
Atoms compose all matter.
An atom is the smallest identifiable unit of an element.
Atoms are responsible for the sensation of smell.
Atoms are the basic building block of nature.
All of the above statements are true.
Animation—Rutherford’s Experiment: Nuclear Atoms
Watch the animation and study Rutherford’s nuclear atom model.
In 1909, Ernest Rutherford performed an experiment to explore the atomic structure. In his experiment, he projected high-speed positively charged α‎ particles
onto a thin gold foil. He found that all α‎particles did not follow the same path. Many particles passed through the foil without any scattering, implying that most
of the space in an atom is empty. Some particles were scattered at a large angle, and very few of them scattered back in the direction from which they had
come. Based on these observations, Rutherford proposed an atomic model, which is known as Rutherford’s atomic model.
Part A – Conclusions from Rutherford’s experiment
Watch the animation depicting Rutherford’s experiment and choose which of the following conclusions are correct.
Check all that apply.
You did not open hints for this part.
ANSWER:
A positive charge is spread equally over the atom.
The atom contains a positively charged nucleus.
The atom does not have positively charged parts.
A positive charge is condensed in one location within the atom.
The atom is a very compact entity without any empty space.
The majority of the space inside the atom is empty space.
Part B – The structure of the atom
On the basis of Rutherford’s experimental observations, which of the following statements predicts the structure of the atom?
Check all that apply.
You did not open hints for this part.
ANSWER:
In an atom, negatively charged electrons are small particles held within a positively charged sphere.
In an atom, most of the mass and the positive charge are located in a small core within the atom called the nucleus.
In an atom, all of the positive and negative charges are randomly distributed.
In an atom, negatively charged electrons are dispersed in the space surrounding the positively charged nucleus of an atom.
Exercise 4.39 – Enhanced – with Feedback
MISSED THIS? Read Section 4.4. You can click on the Review link to access the section in your eText.
Part A
What mass of electrons would be required to just neutralize the charge of 1.8 g of protons? (The mass of a proton is 1.67262 × 10 −24 g, and the mass of
an electron is 9.1 × 10 −28 g .)
Express your answer using two significant figures.
ANSWER:
m e−
=
g
Atomic Structure and Properties of Subatomic Particles
Atoms contain three subatomic particles: protons, electrons, and neutrons.
The figure of a neutral atom shown color-codes each particle for visibility.
Part A
The diagram of a lithium atom is shown in Figure 1. Sort each of the items into the appropriate bin using the diagram of a neutral lithium atom for reference.
Drag each item to the appropriate bin.
You did not open hints for this part.
ANSWER:
Reset
-1 charge
no charge
approximately the same
mass as a neutron
particle labeled “C”
smallest mass of the
three particles
Help
+1 charge
particle labeled “B”
particle labeled “A”
Proton
Neutron
Electron
Conceptual Checkpoint 4.1 – Enhanced – with Feedback
Part A
What is the composition of a charge-neutral atom with a mass of approximately 12 amu?
ANSWER:
3 protons, 3 neutrons, and 6 electrons
12 neutrons and 12 electrons
6 protons and 6 electrons
6 protons, 6 neutrons, and 6 electrons
Chapter 4 Reading Quiz Question 7
Part A
An element is defined by ________.
You did not open hints for this part.
ANSWER:
the sum of protons and neutrons
the number of protons
the number of electrons
the number of neutrons
Chapter 4 Question 19 – Multiple Choice
Part A
Which of the following is NOT a correct name, symbol combination?
ANSWER:
silicon, Si
iron, Fe
phosphorus, P
manganese, Mg
beryllium, Be
Exercise 4.55 – Enhanced – with Feedback
MISSED THIS? Read Section 4.6. You can click on the Review link to access the section in your eText.
Part A
Which of the following elements are main-group elements?
Check all that apply.
ANSWER:
Re
K
Ag
V
Te
Exercise 4.53 – Enhanced – with Feedback
MISSED THIS? Watch IWE 4.2; Read Section 4.6. You can click on the Review link to access the section in your eText.
Part A
Which of the following elements would you expect to lose electrons in chemical changes?
Check all that apply.
ANSWER:
sulfur
potassium
fluorine
copper
barium
Chapter 4 Question 26 – Multiple Choice
Part A
Group 1A elements are also called:
ANSWER:
noble gases.
halogens.
alkaline earth metals.
alkali metals.
none of the above
Exercise 4.68 with eText link
MISSED THIS? Read Section 4.6. You can click on the Review link to access the section in your eText.
Part A
Which of the following pairs of elements do you expect to be most similar?
ANSWER:
N
and O
Ti
and Ga
Ge
and Ga
Ar
and Br
Li
and Na
Exercise 4.51
MISSED THIS? Watch IWE 4.2; Read Section 4.6. You can click on the Review link to access the section in your eText.
Part A
Classify each of the following elements as a metal, nonmetal, or metalloid.
Drag the appropriate items to their respective bins.
ANSWER:
N
Metal
Sr
Mg
As
Reset
Help
Reset
Help
F
Nonmetal
Metalloid
Exercise 4.61
MISSED THIS? Read Section 4.6. You can click on the Review link to access the section in your eText.
Part A
Classify each of the following as a halogen, a noble gas, or neither.
Drag the appropriate items to their respective bins.
ANSWER:
Ga
Halogen
Data Interpretation and Analysis 4.125
Noble gas
He
Cl
F
Kr
Neither
The graph below shows the atomic radii for the first 19 elements in the periodic table.
Atomic radii of elements 1 to 19
Part A
Describe the trend in atomic radius in going from H (atomic number 1) to K (atomic number 19).
You did not open hints for this part.
ANSWER:
As you move right across a period, the atomic radius tends to decrease, and, as you move down a group, the atomic radius tends to decrease.
As you move right across a period, the atomic radius tends to increase, and, as you move down a group, the atomic radius tends to decrease.
As you move right across a period, the atomic radius tends to decrease, and, as you move down a group, the atomic radius tends to increase.
As you move right across a period, the atomic radius tends to increase, and, as you move down a group, the atomic radius tends to increase.
Part B Complete previous part(s)
Instructors: View all hidden parts
Part C Complete previous part(s)
Instructors: View all hidden parts
Part D
Based on the graph, what is the radius of P ?
Express the atomic radius in picometers as an integer.
You did not open hints for this part.
ANSWER:
rP
=
pm
Exercise 4.74 – Enhanced – with Feedback
MISSED THIS? Read Section 4.7. You can click on the Review link to access the section in your eText.
Complete each ionization equation.
Part A
Mg →
––
+ 2e
−
Express your answer as a particle or a chemical formula.
ANSWER:
Part B
Ba → Ba
2+
+
––
Express your answer as a particle or a chemical formula.
ANSWER:
Part C
I+e
−
→
––
Express your answer as a particle or a chemical formula.
ANSWER:
Part D
Al →
––
+ 3e
−
Express your answer as a particle or a chemical formula.
ANSWER:
Exercise 4.78
MISSED THIS? Watch IWE 4.5; Read Section 4.7. You can click on the Review link to access the section in your eText.
Determine the number of protons and electrons in each ion.
Part A
Ga
3+
Enter your answers as integers separated by a comma.
ANSWER:
#p
+
, #e
−
=
Part B
S
2−
Enter your answers as integers separated by a comma.
ANSWER:
#p
+
, #e
−
=
Part C
I
−
Enter your answers as integers separated by a comma.
ANSWER:
#p
+
, #e
−
=
Part D
Ag
+
Enter your answers as integers separated by a comma.
ANSWER:
#p
+
, #e
−
=
Isotopes
Learning Goal:
To understand isotope notation and how to use it to determine the number of protons and neutrons and the mass number for atoms.
Atoms with the same number of protons but different numbers of neutrons are called isotopes. Some elements only have one naturally occurring isotope, while
others such as carbon have two or more. In a naturally occurring sample, isotopes of each element are present in a certain percentage amount called the
percent natural abundance.
The mass number of an isotope is the sum of the number of protons and the number of neutrons for a particular isotope and is symbolized by A .
A = number of protons + number of neutrons
There are several different types of isotope notation. For example, a carbon isotope that has an atomic number of 6 and a mass number of 13 could be
symbolized in any of the following ways: 13
C, carbon-13, or C -13.
6
Part A
Enter the appropriate symbol for an isotope of phosphorus-32 corresponding to the isotope notation A
X.
Z
Express your answer as a chemical symbol using isotope notation.
You did not open hints for this part.
ANSWER:
Part B Complete previous part(s)
Instructors: View all hidden parts
Part C Complete previous part(s)
Instructors: View all hidden parts
Atomic Number and Mass Number
Learning Goal:
To understand the relationship between atomic number and mass number.
Atoms are described by an atomic number and a mass number. The atomic number is the number of protons in the nucleus. The mass number represents the
sum of the protons and the neutrons in the nucleus. If the number of negative electrons is equal to the number of positive protons, then the atom is neutral. If
the number of protons and electrons are not equal, then the atom will have a charge.
For example, a phosphorus ion with 15 protons, 17 neutrons, and 18 electrons would have an atomic number of 15, a mass number of 32, and a charge of − 3.
Part A
What is the mass number of an ion with 104 electrons, 157 neutrons, and a +1 charge?
Express your answer as an integer.
You did not open hints for this part.
ANSWER:
Conceptual Checkpoint 4.6 – Enhanced – with Feedback
Part A
Carbon has two naturally occurring isotopes: 126 C and 136 C. If circles represent protons and squares represent neutrons, which image best represents the
nucleus of the lighter isotope?
ANSWER:
Chapter 4 Question 62 – Multiple Choice
Part A
A fictional element has two naturally occurring isotopes with the natural abundances shown here:
ISOTOPE
ABUNDANCE
18
40.0%
20
60.0%
Which statement is TRUE for this element?
ANSWER:
The atomic mass would be less than 18.
The atomic mass would be exactly 19.
The atomic mass would be closer to 18 than to 20.
The atomic mass would be greater than 20.
The atomic mass would be closer to 20 than to 18.
± Atomic Mass Calculations
Atomic mass is a weighted average of the masses of the naturally occurring isotopes of that element. For example, consider isotopes of lithium:
Isotope
6
7
Abundance Mass
(amu)
(%)
Li
7.5
6.015
Li
92.5
7.016
The atomic mass is therefore
(0.075 × 6.015) + (0.925 × 7.016) = 6.94 amu
Notice that the atomic mass is closer to 7 than it is to 6. That is because the heavier isotope is more abundant.
Part A
On a mission to a newly discovered planet, an astronaut finds gallium abundances of 60.11 % for 69 Ga and 39.89 % for 71 Ga . What is the atomic mass of
gallium for this location?
The mass of 69 Ga is 68.7200 amu . The mass of 71 Ga is 70.9200 amu .
Express your answer to two decimal places, and include the appropriate units.
You did not open hints for this part.
ANSWER:
Part B
The astronaut then measures the abundance of strontium on the new planet, obtaining the following results:
Isotope
86
87
88
Abundance Mass
(amu)
(%)
Sr
Sr
Sr
9.46
85.91
7.00
86.91
83.54
87.91
What is the atomic mass of strontium for this planet?
Express your answer to two decimal places, and include the appropriate units.
You did not open hints for this part.
ANSWER:
Score Summary:
Your score on this assignment is 0.0%.
You received 0 out of a possible total of 21 points.
Homework 4 Chapter 5
Due: 11:59pm on Wednesday, October 5, 2022
To understand how points are awarded, read the Grading Policy for this assignment.
Exercise 5.28 – Enhanced – with Feedback
MISSED THIS? Read Section 5.2. You can click on the Review link to access the section in your eText.
The mass ratio of sodium to fluorine in sodium fluoride is 1.21:1. A sample of sodium fluoride produced 32.5 g of sodium upon decomposition.
Part A
How much fluorine (in grams) was formed?
ANSWER:
mF
=
g
Exercise 5.89
How many chlorine atoms are in each set?
Part A
three carbon tetrachloride molecules
Express your answer as an integer.
ANSWER:
atoms
Part B
four calcium chloride formula units
Express your answer as an integer.
ANSWER:
atoms
Part C
four phosphorous trichloride molecules
Express your answer as an integer.
ANSWER:
atoms
Part D
nine sodium chloride formula units
Express your answer as an integer.
ANSWER:
atoms
Self Assessment 5.1 – Enhanced – with Feedback
MISSED THIS? Read Section 5.2. You can click on the Review link to access the section in your eText.
Part A
Carbon tetrachloride has a chlorine-to-carbon mass ratio of 11.8 : 1 . If a sample of carbon tetrachloride contains 33 g of chlorine, what mass of carbon
does it contain?
ANSWER:
1.0 g C
2.8 g C
11.8 g C
0.36 g C
Exercise 5.88
Write a molecular formula for each molecular model. (White = hydrogen; red = oxygen; black = carbon; blue = nitrogen; yellow = fluorine)
Part A
Express your answer as a chemical formula.
ANSWER:
Part B
Express your answer as a chemical formula.
ANSWER:
Part C
Express your answer as a chemical formula.
ANSWER:
Conceptual Checkpoint 5.2 – Enhanced – with Feedback
Part A
Which formula represents the greatest total number of atoms?
ANSWER:
Pb3(PO4)4
Pb(HSO4)4
Al2(Cr2O7)3
Al(C2H3O2)3
Atoms, Molecular Elements, Molecular Compounds, and Ionic Compounds
Elements and compounds can be classified based on the units that compose them. Elements can be divided into atomic elements and molecular elements,
while compounds can be divided into molecular compounds (also called covalent compounds) and ionic compounds.
Part A
Classify the substances as atomic elements, molecular elements, molecular compounds, or ionic compounds.
Drag each item to the appropriate bin.
You did not open hints for this part.
ANSWER:
Reset
Br 2
Atomic elements
O2
Molecular elements
Part B Complete previous part(s)
Exercise 5.99
Part A
Name the compound PtO2 .
Spell out the full name of the compound.
ANSWER:
Cd
Fe2 O3
Ag
HBr
KCl
Molecular compounds
Help
SO2
Ionic compounds
Instructors: View all hidden parts
Part B
Calculate the formula mass of the compound PtO2 .
Express your answer in atomic mass units to two decimal places.
ANSWER:
Formula mass =
amu
Part C
Name the compound Cl2 O7 .
Spell out the full name of the compound.
ANSWER:
Part D
Calculate the formula mass of the compound Cl2 O7 .
Express your answer in atomic mass units to two decimal places.
ANSWER:
Formula mass =
amu
Part E
Name the compound Al(ClO3 )3 .
Spell out the full name of the compound.
ANSWER:
Part F
Calculate the formula mass of the compound Al(ClO3 )3 .
Express your answer in atomic mass units to two decimal places.
ANSWER:
Formula mass =
Part G
Name the compound PF5 .
Spell out the full name of the compound.
ANSWER:
Part H
amu
Calculate the formula mass of the compound PF5 .
Express your answer in atomic mass units to two decimal places.
ANSWER:
Formula mass =
amu
Interactive Worked Example: Writing Formulas for Ionic Compounds containing Polyatomic Ions
First, launch this video. During the video, you’ll be asked a conceptual question about the example. After watching the video, answer the related questions at
the right. You can watch the video again at any point.
Part A
Write the formula for the compound that forms between gallium and phosphate ions.
Express your answer as a chemical formula.
ANSWER:
Part B
Write the formula for the compound that forms between sodium and chlorite ions.
Express your answer as a chemical formula.
ANSWER:
Exercise 5.66 – Enhanced – with Feedback
MISSED THIS? Watch KCV 5.7, IWE 5.14; Read Section 5.7. You can click on the Review link to access the section in your eText.
Name each of the following ionic compounds containing a polyatomic ion.
Part A
Ba(OH)2
Spell out the full name of the compound.
ANSWER:
Part B
Fe(OH)3
Spell out the full name of the compound.
ANSWER:
Part C
CuNO 2
Spell out the full name of the compound.
ANSWER:
Part D
PbSO4
Spell out the full name of the compound.
ANSWER:
Part E
KClO
Spell out the full name of the compound.
ANSWER:
Part F
Mg(C2 H 3 O2 )2
Spell out the full name of the compound.
ANSWER:
Chapter 5 Question 38 – Multiple Choice
Part A
Which formula shown is incorrect for the name given?
ANSWER:
lithium sulfate: LiSO4
calcium nitrate: Ca(NO3)2
strontium carbonate: SrCO3
ammonium cyanide: NH4CN
potassium acetate: KC2H3O2
Writing Ionic Formulas
Learning Goal:
To learn how to write ionic formulas.
Here are some things to remember when dealing with ionic compounds:
By convention, the cation is named first and the anion is named second.
A Roman numeral in the name indicates the charge of the cation.
The subscripts in the formula represent the number of positive and negative ions that give an overall charge of zero.
Consider tin(IV) sulfide. The Roman numeral tells us that the cation has a +4 charge: Sn4+ . The periodic table tells us that sulfide has a −2 charge: S2− . To
balance the +4 charge on tin, we need two sulfide ions: 2(−2) = −4. So the formula is written as SnS2 .
Part A
What is the formula for copper(II) oxide?
Express your answer as a chemical formula.
You did not open hints for this part.
ANSWER:
Part B
What is the formula for strontium chloride?
Express your answer as a chemical formula.
You did not open hints for this part.
ANSWER:
Part C
Sort the following iron compounds by whether the cation is iron(II) or iron(III).
Drag each item to the appropriate bin.
You did not open hints for this part.
ANSWER:
Reset
FeO
FeBr 2
Iron(II)
Fe3 P 2
Fe2 S 3
FeN
Help
FeI3
Iron(III)
Naming Ionic Compounds
Ionic compounds are compounds in which two or more ions are held together by electrical attraction. The ion with a positive charge is called a cation, which is
usually a metal or a polyatomic ion such as the ammonium ion (NH4 + ). The ion with a negative charge is called an anion, which is either a nonmetal or a
polyatomic ion.
Ionic compounds containing a group 1A metal, group 2A metal, or aluminum cation contain metals that form only one ion. For ionic compounds that contain
only group 1A, group 2A, or aluminum cations, the charge on the cation does not need to be included in the compound name since it does not vary.
It is not easy to determine the charge of a transition element from the group number because it forms two or more positive ions. The sum of the charges on the
anions must be used to determine the charge on the cation, and the charge must be indicated using Roman numerals in parentheses following the cation.
Follow these general rules for naming ionic compounds:
1. Name the cation first according to its element name. If the cation is a transition metal, add the charge on the cation as a Roman numeral in
parentheses following the cation name.
2. Name the anion second according to the first syllables of the element name followed by the ending ide.
Part A
Name the ionic compound CaBr2 .
Spell out the full name of the ionic compound.
You did not open hints for this part.
ANSWER:
Metals with variable charge
Ionic compounds with transition elements contain metals that can form more than one type of positive ion (cation) that have different charges. To distinguish
between two compounds that contain the same transition elements, we use Roman numerals to specify the charge on the metal cation. Roman numerals are
indicated with capital letters, where the capital letter I indicates one, II indicates two, III indicates three, and IV indicates four.
To find the charge on a transition metal cation, start by determining the amount of negative charge contributed by the anion in the formula. The total number of
positive and negative charges must equal zero.
For example, gold is a transition metal and can form Au+ and Au3+ ions. AuCl3 contains three Cl− ions that require a 3+ charge on the gold ion to form a
neutral compound.
For AuCl3 , Charge on cation + Charge on anion
=
0
charge
=
0
? + 3 (1−)
=
0
(3+) + (3−)
=
0
−
Au charge + 3 Cl
Therefore, the charge of the cation is 3+.
To indicate the 3+ charge for the gold ion Au3+ , a Roman numeral (III) with three capital letter I’s is placed immediately after the gold cation. The full
compound name of AuCl3 is gold (III) chloride.
Part B
If the metal in the ionic compound is a transition element (with variable charge metal ions), the ionic charge is written as a Roman numeral following the
element name of the cation.
Name the ionic compound PbCl4 .
Spell out the full name of the ionic compound.
You did not open hints for this part.
ANSWER:
Polyatomic ions
A polyatomic ion is a group of nonmetal atoms that carries an electrical charge. It is composed of two or more atoms covalently bonded or in the form of a metal
complex that is considered as a single unit. Almost all polyatomic ions are anions with charges 1− , 2− , or 3− . One exception for this rule is NH4 + , which is a
cation.
Some of the common polyatomic ions are in the table.
Name of polyatomic ions
Formula of polyatomic ions
Hydrogen carbonate
HCO3
Carbonate
CO3
2−
Hydroxide
OH
Nitrate
NO3
Phosphate
Sulfate
PO4
SO4
−
−
−
3−
2−
When naming polyatomic ionic compounds, first write the positive ion, usually a metal. Then, write the name for the polyatomic ion. No prefixes are used when
naming a polyatomic compound.
Part C
Name the ionic compound CuSO4 .
Spell out the full name of the ionic compound.
You did not open hints for this part.
ANSWER:
Exercise 5.69
MISSED THIS? Watch KCV 5.7, IWE 5.14; Read Section 5.7. You can click on the Review link to access the section in your eText.
Write a formula for each ionic compound.
Part A
cobalt(II) bromide
Express your answer as a chemical formula.
ANSWER:
Part B
silver chlorate
Express your answer as a chemical formula.
ANSWER:
Part C
sodium hydroxide
Express your answer as a chemical formula.
ANSWER:
Part D
sodium sulfate
Express your answer as a chemical formula.
ANSWER:
Part E
sodium hydrogen sulfate
Express your answer as a chemical formula.
ANSWER:
Part F
sodium hydrogen sulfite
Express your answer as a chemical formula.
ANSWER:
Polyatomic Ions
A polyatomic ion comprises a group of atoms that carry an overall charge. There is no easy way to learn the names of polyatomic ions. Memorizing the most
common ones is important.
Formula
ammonium
−
nitrate
2−
sulfate
2−
carbonate
NH 4
NO3
SO4
Name
+
CO3
PO4
3−
phosphate
−
chlorate
ClO3
Part A
What is the name of the ionic compound BaCO3 ?
Enter the compound name.
You did not open hints for this part.
ANSWER:
Part B
What is the formula for the ionic compound ammonium nitrate?
Express your answer as a chemical formula.
You did not open hints for this part.
ANSWER:
Naming Covalent Compounds
Learning Goal:
To name covalent compounds using the chemical formulas and systematic naming rules.
In naming covalent compounds, Greek prefixes are used to indicate the number of atoms of each element present. For example, CO2 is called carbon dioxide.
Note that the ending is changed to ide. Also, note that the prefix mono is usually omitted.
Number Prefix
Part A
What is the name of the covalent compound CCl4 ?
Enter the name of the compound.
You did not open hints for this part.
ANSWER:
Part B
What is the name of the covalent compound Cl2 O?
Enter the name of the compound.
1
mono
2
di
3
tri
4
tetra
5
penta
6
hexa
7
hepta
8
octa
9
nona
10
deca
You did not open hints for this part.
ANSWER:
Naming Binary Acids and Oxyacids
Acid refers to any molecule that is able to dissociate in water to form H+ (aq), which mean acids must contain at least one hydrogen atom in their formula unit.
There are six strong acids (containing strongly acidic hydrogen atoms), which are acids that completely dissociate in water (HCl, HBr, HI, HNO3 , HClO4 ,
and H2 SO4 ). All other acids, which partially dissociate, are considered weak acids (containing weakly acidic hydrogen atoms).
Acids are generally categorized into one of the two following groups: binary acids and oxyacids. A binary acid is simply composed of two elements, which are
hydrogen and a nonmetal. Oxyacids are composed of at least one hydrogen, one metal or nonmetal, and one oxygen. The names of binary acids are based
on their chemical formula, and the following procedure demonstrates how hydrochloric acid is derived from HCl:
hydro − (pref ix)
root name of nonmetal
hydro−
−chlor−
+
−ic ending
acid
−ic
acid
Note that the -ine ending is dropped from the element name to form the root of the nonmetal chlorine before adding the -ic ending. Elements have various
endings that are dropped before adding the -ic suffix, which can include -ogen, -ium, -on, -ine, -orus, etc.
Part A
Use the naming conventions to complete the following formula-name pairs of binary acids.
Match the acid names and chemical formulas in the left column to the appropriate blanks in the chemical formulas and acid names on the right.
Make certain each acid name and chemical formula is complete before submitting your answer.
You did not open hints for this part.
ANSWER:
Reset
H 2 Te
Acid name:
Help
; Chemical formula: H2 Se
hypofluorous acid
Acid name: hydroiodic acid; Chemical formula:
H 2 TeO3
hydrofluoric acid
selenic acid
Acid name:
; Chemical formula: HF
Acid name: hydrotelluric acid; Chemical formula:
HIO3
hydroselenic acid
HI
Oxyacids and organic acids
You have explored the naming conventions of binary acids in the previous part (involving only two elements). We will now consider acid compounds in which
there are more than two elements present. A polyatomic ion is an ion that is composed of more than one atom. When polyatomic ions are bonded with H+ ,
several types of acids are formed, which include oxyacids and organic acids.
Oxyacids are composed of at least two other elements beside hydrogen because they contain oxyanions. An oxyanion is a specific type of polyatomic ion that
is made up of oxygen and another element that could be either a metal or nonmetal. Organic acids contain at least carbon, hydrogen, and oxygen (i.e., organic
compounds). Common oxyanions and organic ions are listed in the table of polyatomic ions below.
Oxyanion Name
Oxyanion
Formula
borate
BO3
nitrite
NO2
nitrate
NO3
Organic Ion Name
Organic Ion
Formula
3−
carbonate
CO3
−
acetate
C2 H 3 O2
−
ascorbate
C6 H 7 O6
2−
−
−
sulfite
SO3
2−
citrate
2−
formate
CHOO
−
lactate
C3 H 5 O3
−
oxalate
C2 O4
−
benzoate
C7 H 6 O2
−
permanganate
MnO4
sulfate
SO4
bromite
BrO2
bromate
BrO3
chlorite
ClO2
chlorate
ClO3
iodite
IO2
iodate
IO3
phosphite
PO3
phosphate
PO4
C6 H 5 O7
3−
−
−
2−
−
−
−
−
3−
3−
To name an oxyacid, change the -ite ending to -ous or the -ate ending to -ic, then add the word acid to the end (acid is spaced). The root is normally unchanged
for oxyacids. For example, the acid form of the oxyanion nitrate is nitric acid. The relationship between the oxyanion name and oxyacid name is summarized
below.
acid root
+
acid suf f ix
oxyanion root
+
−ous (f rom −ite ending)
oxyanion root
+
−ic (f rom −ate ending)
Part B
Use the naming conventions and table of polyatomic ions to complete the following formula-name pairs of oxyacids and organic acids.
Match the acid names and chemical formulas in the left column to the appropriate blanks in the chemical formulas and acid names on the right.
Make certain each acid name and chemical formula is complete before submitting your answer.
You did not open hints for this part.
ANSWER:
Reset
manganic acid
Acid name:
Help
; Chemical formula: H2 MnO4
HIO2
Acid name: iodous acid; Chemical formula:
HIO3
chromic acid
boric acid
formic acid
Acid name: sulfuric acid; Chemical formula:
Acid name:
; Chemical formula: HCOOH
Acid name:
; Chemical formula: H3 BO3
acetic acid
hydroboric acid
H2 S
H 2 SO4
Part C
The oxyacids containing oxygen (O ) and phosphorous (P ) are named differently than the oxyanions on which they are based. You have just learned that in
general -ite endings are changed to -ous while -ate endings are changed to -ic when naming the acid. However, for the acids of oxyanions based on
phosphorus, the root also changes. The roots for the oxyanions and oxyacids of phosphorus are shown below.
oxyanion root: phosph
oxyacid root: phosphor
Although the exception exists for the root, the prefixes and suffixes of these oxyacids still follow the conventions for naming oxyacids. Using the table of
oxyanions given in the transition before Part B and the roots shown above, give the name of the oxyacid H3 PO4 below.
Spell out the full name of the acid.
You did not open hints for this part.
ANSWER:
Part D Complete previous part(s)
Instructors: View all hidden parts
Exercise 5.79
MISSED THIS? Watch IWE 5.14; Read Section 5.9. You can click on the Review link to access the section in your eText.
Name each acid.
Part A
HClO
Spell out the full name of the acid.
ANSWER:
acid
Part B
HClO2
Spell out the full name of the acid.
ANSWER:
acid
Part C
HClO3
Spell out the full name of the acid.
ANSWER:
acid
Part D
HClO4
Spell out the full name of the acid.
ANSWER:
acid
Exercise 5.81
MISSED THIS? Watch IWE 5.14; Read Section 5.9. You can click on the Review link to access the section in your eText.
Write a formula for each acid.
Part A
iodous acid
Express your answer as a chemical formula.
ANSWER:
Part B
hydrochloric acid
Express your answer as a chemical formula.
ANSWER:
Part C
hydrosulfuric acid
Express your answer as a chemical formula.
ANSWER:
Chapter 5 Question 64 – Multiple Choice
Part A
Which of the following has the largest formula mass?
ANSWER:
H2O
SO2
SiO2
CO2
NO2
Chapter 5 Question 65 – Multiple Choice
Part A
Which of the following compounds have the smallest formula mass?
ANSWER:
NO2
H2O
SiO2
CO2
SO2
Formula Mass
Learning Goal:
To learn to calculate the formula mass of a substance.
The average mass of molecules or formula units that compose a compound is called the formula mass or formula weight. The formula mass of a substance is
expressed in atomic mass units or amu.
The formula mass is the sum of the atomic masses of all the atoms in its chemical formula. The atomic mass of an atom can be found by using the periodic
table.
To calculate the formula mass of ethane, C2 H6 , use the following steps:
f ormula mass
= 2(atomic mass of C) + 6(atomic mass of H)
= 2(12.01 amu) + 6(1.01 amu)
= 30.08 amu
How to calculate formula mass
Part A
What is the formula mass of magnesium chloride, MgCl2 ?
Express your answer to four significant figures and include the appropriate units.
You did not open hints for this part.
ANSWER:
Part B
What is the formula mass of calcium nitrate, Ca(NO3 )2 ?
Express your answer to five significant figures and include the appropriate units.
You did not open hints for this part.
ANSWER:
Part C
What is the formula mass of ethanol, C2 H5 OH?
Express your answer to four significant figures and include the appropriate units.
You did not open hints for this part.
ANSWER:
Score Summary:
Your score on this assignment is 0.0%.
You received 0 out of a possible total of 21 points.
Homework 5 Chapter 6
Due: -To understand how points are awarded, read the Grading Policy for this assignment.
Interactive Worked Example: Converting between Moles and Number of Atoms
First, launch this video. During the video, you’ll be asked a conceptual question about the example. After watching the video, answer the related
questions at the right. You can watch the video again at any point.
Part A
How many gold atoms are in a pure gold ring containing 5.61 × 10 −2 mol Au?
Express your answer in atoms to three significant figures.
ANSWER:
atoms
± Conversions Involving Moles
The mole is defined as the number of atoms in exactly 12 g of carbon-12. The mole equals 6.022 × 10 23 items of whatever you are counting. This
number is also called Avogadro’s number, after Amadeo Avogadro (1776–1856).
Molar mass is the mass of 1 mol of atoms of an element; for compounds, molar mass is the mass of 1 mol of molecules or formula units. Molar mass
can be used to convert mass to moles for any element or compound.
Part A
How many grams are in 2.60 mol of sodium chloride (NaCl)?
Express your answer numerically in grams.
You did not open hints for this part.
ANSWER:
g
Part B
How many water molecules are in a block of ice containing 1.00 mol of water (H2 O)?
Express the number of molecules numerically.
You did not open hints for this part.
ANSWER:
molecules of H 2 O
Part C Complete previous part(s)
Instructors: View all hidden parts
Exercise 6.7
What is the mass of 1 mol of atoms of each element?
Part A
P
Express your answer in grams to two decimal places.
ANSWER:
Mass =
g
Part B
Pd
Express your answer in grams to two decimal places.
ANSWER:
Mass =
g
Part C
C
Express your answer in grams to two decimal places.
ANSWER:
Mass =
g
Part D
Sc
Express your answer in grams to two decimal places.
ANSWER:
Mass =
g
Exercise 6.41
MISSED THIS? Watch IWE 6.3; Read Section 6.3. You can click on the Review link to access the section in your eText.
Part A
How many titanium atoms are in a pure titanium bicycle frame with a mass of 1.32 kg ?
Express your answer in atoms to three significant figures.
ANSWER:
Ti
atoms
Exercise 6.36
MISSED THIS? Watch IWE 6.3; Read Section 6.3. You can click on the Review link to access the section in your eText.
Part A
What is the mass of 3.66×1021 platinum atoms?
Express your answer with the appropriate units.
ANSWER:
m
=
Calculating Molar Mass
The unit of measurement that is the mole (commonly abbreviated as mol) is used to describe 6.022 × 10 23 units of an atom, ion, or compound in the
same way that a dozen is used to refer to 12 units of an item. This number, 6.022 × 10 23 , is known as Avogadro’s number and is named for the
Italian physicist Amedeo Avogadro. For example, 1 mole of chlorine atoms contains 6.022 × 10 23 chlorine atoms, and 1 mole of carbon dioxide
contains 6.022 × 10 23 CO2 molecules.
The molar mass of an element or a molecule is equal to the mass of 1 mole of that element or compound. In other words, molar mass reflects the
mass of 6.022 × 10 23 units of a substance.
To find the molar mass of a particular element, simply express the atomic mass (which is generally displayed beneath the chemical symbol of each
element on the periodic table) of that element in grams. For example, carbon is shown to have an atomic mass of 12.01 on the periodic table.
Therefore, it has a molar mass of 12.01 grams per mole. Finding the molar mass of a compound involves multiplying the molar mass of each element
by its subscript in the chemical formula and adding the results. Subscripts only apply to the chemical symbol directly preceding them unless
parentheses are used (i.e., for CO2 , the molar mass of oxygen is multiplied by 2 but the molar mass of carbon is not).
Part A
Given the atomic mass of select elements, calculate the molar mass of each salt.
Element
Molar mass
(g/mol)
Beryllium (Be )
9.012
Calcium (Ca)
40.08
Cobalt (Co)
58.93
Cadmium (Cd)
112.41
Fluorine (F)
19.00
Match the numbers to the appropriate blanks in the sentences below. Make certain each sentence is complete before submitting your
answer.
You did not open hints for this part.
ANSWER:
Reset
28.01 g/mol
1. The molar mass of BeF2 is
.
2. The molar mass of CoF2 is
.
3. The molar mass of CaF2 is
.
4. The molar mass of CdF2 is
.
Help
59.08 g/mol
47.01 g/mol
77.93 g/mol
78.08 g/mol
96.93 g/mol
131.41 g/mol
150.41 g/mol
Part B
Calculate the molar mass for Mn3 O4 , an oxide of manganese.
Express your answer to five significant figures.
You did not open hints for this part.
ANSWER:
Molar mass =
g/mol
Part C
Calculate the molar mass of norepinephrine (C8 H11 NO3 ), a hormone that helps increase blood pressure by stimulating blood vessels to
constrict.
Express your answer to five significant figures.
You did not open hints for this part.
ANSWER:
Molar mass =
g/mol
Exercise 6.122
Progesterone is a female sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis. Elemental analysis of progesterone gave the
mass percent composition: C , 80.19 %; H , 9.63 %; O , 10.18 %. The molar mass of progesterone is 314.51 g/mol.
Part A
Find the molecular formula of progesterone.
Express your answer as a chemical formula.
ANSWER:
Chapter 6 Question 26 – Multiple Choice
Part A
What is the molar mass of aluminum sulfate?
ANSWER:
123.0 g/mol
342.2 g/mol
315.2 g/mol
306.2 g/mol
278.0 g/mol
Key Concept Video: Chemical Formulas as conversion Factors
First, select to launch the Chemical Formulas as conversion Factors video. During the video, you’ll be asked a conceptual question about the key
concept. After watching the video, answer the related question at the right. You can watch the video again at any point to review.
Part A
How many moles of K are present in 12 moles of K2 CO3 ?
You did not open hints for this part.
ANSWER:
24 mol K
36 mol K
12 mol K
6 mol K
Part B
How many grams of K are present in 32 g of K2 CO3 ?
You did not open hints for this part.
ANSWER:
9.1 g K
64 g K
4.5 g K
18 g K
Part C
How many grams of O are present in 25 g MgCO3 ?
You did not open hints for this part.
ANSWER:
75 g O
14 g O
1.6 g O
4.7 g O
Exercise 6.78
MISSED THIS? Read Section 6.6. You can click on the Review link to access the section in your eText.
The iodide ion, usually consumed as potassium iodide, is a dietary mineral essential to good nutrition. In countries where potassium iodide is added to
salt, iodine deficiency or goiter has been almost completely eliminated. The recommended daily allowance (RDA) for iodine is 150 μg/day.
Part A
How much potassium iodide (76.45% I ) should you consume to meet the RDA?
ANSWER:
μg
Exercise 6.92
MISSED THIS? Watch KCV 6.8, IWE 6.11; Read Section 6.8. You can click on the Review link to access the section in your eText.
Lactic acid, employed in pharmaceutical technology to produce water-soluble lactates, has the following elemental composition: C , 40.00 %; H , 6.71
; , 53.29 %.
% O
Part A
Calculate the empirical formula of lactic acid.
Express your answer as a chemical formula.
ANSWER:
Interactive Worked Example 6.11: Obtaining an Empirical Formula from Experimental Data
First launch this video. During the video, you’ll be asked a conceptual question about the example. After watching the video, answer the related
questions at the right. You can watch the video again at any point.
Part A
Ibuprofen, an aspirin substitute, has a mass percent composition of 75.69% C , 8.80% H , and 15.51% O . Calculate its empirical formula.
Express your answer as a chemical formula.
ANSWER:
Part B
A laboratory analysis of vanillin, the flavoring agent in vanilla, indicates that its mass percent composition is 63.15% C , 5.30% H , and 31.55% O .
Determine the empirical formula of vanillin.
Express your answer as a chemical formula.
ANSWER:
Part C
The rotten smell of a decaying animal carcass is partially due to a nitrogen-containing compound called putrescine. Elemental analysis of
putrescine indicates that it consists of: 54.50% C , 13.73% H , and 31.77% N . Calculate the empirical formula of putrescine.
Express your answer as a chemical formula.
ANSWER:
Part D
Citric acid, the compound responsible for the sour taste of lemons, has an elemental composition of 37.51% C , 4.20% H , and 58.29% O
Calculate the empirical formula of citric acid.
Express your answer as a chemical formula.
ANSWER:
Exercise 6.101
MISSED THIS? Read Section 6.9. You can click on the Review link to access the section in your eText.
The molar masses and empirical formulas of several compounds containing carbon and chlorine are as listed here. Find the molecular formula of each
compound.
Part A
474.60 g/mol, CCl
Express your answer as a chemical formula.
ANSWER:
Part B
131.39 g/mol, C2 HCl3
Express your answer as a chemical formula.
ANSWER:
Part C
241.91 g/mol, C2 HCl
Express your answer as a chemical formula.
ANSWER:
Exercise 6.130
The ozone hole over Antarctica on September 24, 2009. The dark blue and purple areas over the South Pole represent very depressed ozone
concentrations.
Part A
Because of increasing evidence of damage to the ozone layer, chlorofluorocarbon (CFC) production was banned in 1996. However, there are
about 100 million auto air conditioners that still use CFC-12 (CF2 Cl2 ). These air conditioners are recharged from stockpiled supplies of CFC-12.
If each of the 100 million automobiles contains 1.0 kg of CFC-12 and leaks 27 % of its CFC-12 into the atmosphere per year, how much Cl in
kilograms is added to the atmosphere each year due to auto air conditioners? (Assume two significant figures in your calculations.)
Express your answer using two significant figures.
ANSWER:
m Cl
=
kg
Exercise 6.111
The rock in a particular iron ore deposit contains 85 % Fe2 O3 by mass.
Part A
How many kilograms of the rock must be processed to obtain 4300 kg of iron?
Express your answer using two significant figures.
ANSWER:
m rock
=
kg
Exercise 6.120
Caffeine, a stimulant found in coffee and soda, has the mass percent composition: C , 49.48%; H , 5.19%; N , 28.85%; O , 16.48%. The molar mass of
caffeine is 194.19 g/mol.
Part A
Find the molecular formula of caffeine.
Express your answer as a chemical formula.
ANSWER:
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