Chemistry Quantitative Analysis Questionnaire

Data Analysis:Determine Molarity of Standardized Sodium Hydroxide Solution
A separate calculation is needed for each trial.
1. Calculate the moles of KHP present in the titration.
mass KHP, g
molar mass KHP, g/mol)
2. Relate the moles of KHP to the moles of NaOH added in the titration. Remember the
stoichiometry of the reaction is one mole KHP per one mole NaOH.
(mole KHP)
1 mol NaOH
1 mol KHP
= mole KHP
S =
3. Determine the molarity of the sodium hydroxide solution by dividing the moles of NaOH
added in the titration by the volume of NaOH solution at the endpoint. Remember to
convert the volume of sodium hydroxide to liters.
mole NaOH
(volume NaOH to reach endpoint, mL)
= mole NaOH
= molarity NaOH,
1 L
1000 mL.
mol
4. Calculate the average molarity for the sodium hydroxide solution. Remember to analyze
the molarity of individual trials for outliers before taking the average.
5. Determine the standard deviation (s) in the average molarity of the sodium hydroxide
solution. If only three trails were used to determine the average molarity there will only
be three terms in the numerator and the denominator will be (3-1).
(Mtrial 1 – Maverage)² + (Mtrial 2 − Maverage)² + (Mtrial 3 − Maverage)² + (Mtrial 4 — Maverage)²
4-1Determine Molar Mass of the Unknown Acid
A separate calculation is needed for each trial. The results of all trials should be averaged.
Outliers may be excluded from the average.
1. Calculate the moles of NaOH added in the titration.
(volume NaOH to reach endpoint, mL) T) (m
1 L
1000 mL/
(1 mole acetic acid
In mole NaOH
(mole NaOH)|
2. Relate the moles of NaOH added in the titration to moles of Unknown acid where n = 2
for a diprotic acid and n = 3 for a triprotic acid.
(volume of Unknown acid, L) (concentration,
(moles Unknown acid)
Acid Name
mole
molarity NaOH,-
3. Determine the molar mass of the Unknown acid solution by dividing the mass of the
sample of acid by the number of moles of acid at the endpoint of the titration.
Ascorbic Acid
Boric Acid
Citric Acid monohydrate
Fumaric Acid
Oxalic acid dihydrate
Phthalic acid
Succinic acid
Tartaric acid
= mole Unknown acid
= mole NaOH
4. Identify the acid by comparing the experimentally determined molar mass of the Unknown
acid with the molar mass of the acids in the chart below.
= molar mass Unknown acid,
Molar Mass, g/mol
176.1
61.8
210.1
116.1
126.1
166.0
118.8
150.1
g
mol