Refliction 3

Using robust details and ample evidence, create a reflection paragraph that describes 4 learning objectives you met while performing this experiment.  View the learning objectives from the lab manual provided and select four to focus your writing on. Make this a well-constructed paragraph by including an introduction and conclusion sentences, avoiding bulleted lists. Challenge yourself to meet a 250-word count goal.

Virtual Lab Manual
Reaction Kinetics:
The Essentials
Synopsis
Power up the Squadrone! In this simulation, you will learn the main factors that influence the
rate of a chemical reaction, and use this knowledge to improve the output of our drone
transporter’s propulsion fuel. The changed reaction affects how much heat is generated
though, which can potentially overheat the drone. You will need to dive into potential energy
diagrams to figure out what’s going on there.
Kinetics at the core
After meeting Dr. One at the lab facility and getting up to speed on the chemical reaction
we’re working with, you will explore hands-on and optimize the key factors involved in the
kinetics of the reaction. We will use the power of the rate law and the Arrhenius’ equation to
really pinpoint what’s going on, and also link this to effects at the molecular level. You will be
able to dynamically adjust the parameters of the reaction as you see fit, and see the direct
effect on the rate of the reaction and concentration of the reactants and products.
Potential for more energy
After having optimized the reaction, you will move on to explore how the levels of potential
energy for the reactants and products of the reaction affect the heat being produced, and
how the use of a catalyst can affect the activation energy.
Don’t dip in the acid
Ultimately, you will need all your gathered knowledge on kinetics to get the reaction to
produce enough propulsion for the transport drone. Will you be able to enable it to get
across the acid lake?
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Learning Objectives
At the end of this simulation, you will be able to…
● Describe the main factors that influence the rate of a chemical reaction (reactant
concentration, temperature, solvent, use of catalyst), and give examples of their effect
● Assess the reaction rate of simple reactions by examining concentration data over
time.
● Explain the relation between temperature and reaction rate
● Describe the relation between collision theory and activation energy.
● Interpret reaction energy diagrams, and relate them to energy changes during the
course of a reaction.
● Suggest a suitable experimental setup for measuring the kinetics of a reaction.
Techniques in Lab
None
Theory
Decomposition of hydrogen peroxide
Hydrogen peroxide (H2O2) is a strong oxidizer and contains a peroxide group, which has an
oxygen-oxygen single bond. Peroxide bonds are unstable, which causes the compound to
easily decompose. At room temperature, diluted hydrogen peroxide is colorless.
Figure 1: The decomposition reaction of hydrogen peroxide into oxygen and water.
Hydrogen peroxide can be used to treat various inorganic and organic pollutants, as a
bleaching agent in the paper and textile industries, and as a disinfectant. At high
temperatures, or at the presence of a catalyst, purified hydrogen peroxide decomposes into
oxygen and water. When the rate of hydrogen peroxide decomposition is fast enough,
hydrogen peroxide can be used as a monopropellant for submarines and satellites.
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Reaction rate
The reaction rate is the change in concentration of a reactant or product per unit of time.
Figure 2: The plot of the number of reactant (A) and product (B) molecules over time. The
reactant is decreasing while the product is increasing with time.
Take the following reaction as an example:
The reaction rate can be determined by measuring the rate of disappearance of reactant A.
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[A2] : Concentration of A at t2 (M)
[A1] : Concentration of A at t1 (M)
t2 : Time 2 (s)
t1 : Time 1 (s)
The units for reaction rate are (mol/L)/s or M/s.
The reaction rate can also be expressed as the rate of appearance of product B.
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●
●
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[B2] : concentration of B at t2 (M)
[B1] : concentration of B at t1 (M)
t2 : Time 2 (s)
t1 : Time 1 (s)
With the units of the reaction rate still being (mol/L)/s or M/s.
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Things to consider
Be mindful of the difference between using the reactant (A) vs. product (B) for determining
the reaction rate. The value of the reaction rate should be positive, and since [A] decreases
with time, Δ[A] is negative. Therefore, we add a negative sign to the formula when
expressing the reaction rate as the disappearance of the reactant.
We also need to consider the stoichiometry relationship between product and reactant. In
our example, 2 mol of B appears for 1 mol of A. Therefore, the rate of appearance of B is
twice the rate of disappearance of A.
The reaction rate formula for our example can be summarized as follows:
Collision model
The collision model or collision theory is based on kinetic-molecular theory. It seeks to
explain the effect of concentration and temperature on the reaction rate. According to the
model, reactant molecules only react when they collide with correct orientation and
enough energy to overcome the activation energy. Increasing the rate of successful
collisions increases the reaction rate.
Figure 3: Two requirements must be satisfied for reactants to collide successfully: 1) The
collision energy must be equal or exceed the activation energy. 2) The orientation must
allow the formation of new chemical bonds.
Potential energy diagram
A potential energy diagram shows the changes of potential energy of a system as it
undergoes a chemical reaction.
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The activation energy (Ea) represents the minimum energy required to initiate a reaction.
The reaction rate highly depends on the activation energy. The lower the activation energy,
the higher the reaction rate.
The enthalpy change of the reaction, ΔH, is estimated as the difference in “heat energy”
between the reactants and products (at constant pressure).
The molecule at the top of the curve or energy barrier is called the activated complex or
the transition state.
Figure 4: The change in potential energy as a function of reaction progress for the reaction
2H2O2 –> 2H2O + O2. This is an exothermic reaction.
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