KBHS CHEMISTRY
2015
2015
Achievement Standard 91161 (v2)
Carry out quantitative analysis
Credits: 4
Practise Assessment
NAME
Achievement
Carry out quantitative
analysis
Merit
Carry out in-depth
quantitative analysis
Excellence
Carry out comprehensive
qualitative analysis
KBHS CHEMISTRY
2015
SUBJECT REFERENCE: CHEMISTRY 2.1
Practise Assessment
Achievement Standard 91161 (v2)
Carry out quantitative analysis
Credits: 4
Time allowed: 2 hours
Student Instructions Sheet
This is an individual practical and written activity which is carried out over the course of
two periods. You will be assessed on each part and you are required to record your results
and calculations.
Make sure you:
 Show all working
 Give answers to the correct number of significant figures
 Use appropriate units
Task 1 requires you to carry out an acid-base volumetric analysis. You will have one hour
to complete this part of the assessment.
Task 2 requires you to solve simple quantitative problems. You will have one hour to
complete this part of the assessment.
Each task must be completed independently. You will be instructed what task you are to
begin with.
KBHS CHEMISTRY
2015
Task 1: Volumetric Analysis
Practical activity
You are required to perform a titration to analyse the concentration of a solution of
hydrochloric acid provided by your teacher. You will need:
 25.0 mL pipette
 burette
 3 conical flasks
 hydrochloric acid solution
 distilled water
 phenolphthalein indicator
 wash bottle
 standard sodium hydroxide solution (concentration =
mol.L-1)
Method:



Titrate 25.0 mL samples of the hydrochloric acid solution with the standard sodium
hydroxide solution using phenolphthalein as an indicator for the end point of the
reaction
Repeat the titration procedure until you have three (minimum) concordant results
Record all of your burette readings in a systematic format that clearly indicates the
volume of sodium hydroxide used in each titration
Results:
KBHS CHEMISTRY
2015
Calculations:
Calculate the average titre volume of sodium hydroxide
Use the known concentration of sodium hydroxide to calculate the amount of sodium
hydroxide used in the titration.
The balanced equation for the reaction occurring in the titration is:
NaOH + HCl  NaCl + H2O
Calculate the concentration of hydrochloric acid solution used in the titration. Make sure to
give your answer to three significant figures
KBHS CHEMISTRY
2015
Task Two: Written Problems
The molar masses below will help you carry out the following calculations.
M(C) = 12.0 g.mol-1
M(O) = 16.0 g.mol-1
M(C2H6O) = 46 g.mol-1
M(H) = 1.00 g.mol-1
M(N) = 14.0 g.mol-1
-1
M(NH4NO3) = 80.0 g.mol M(C12H22O11) = 342 g.mol-1
M(PbI2) = 461 g.mol-1
M(Pb(NO3)2) = 331 g.mol-1
Question One
A compound is 30.4% nitrogen and 69.6% oxygen, with a molar mass of 92.0 g.mol-1,
calculate the empirical formula and molecular formula
Empirical formula:
Molecular formula:
Question Two
What is the mass of 0.606 mol of NH4NO3?
Question Three
Sucrose is a naturally occurring sugar. How many moles of sucrose are present in
22.0 mL of 0.180 mol.L-1 sucrose solution?
KBHS CHEMISTRY
2015
Question Four
Calculate the %C, %H and %O composition of sucrose (C12H22O11).
%C composition:
%H composition:
%O composition:
Question Five
How many moles of ethanol, C2H6O, in 173 g of ethanol?
KBHS CHEMISTRY
2015
Question Six
25 mL samples of KOH solution are titrated against 0.0344 mol.L-1 H2SO4 solution. The
average titre of H2SO4 was 22.3 mL. Calculate the concentration of the KOH solution.
2 KOH + H2SO4  K2SO4 + 2 H2O
Question Seven
Lead nitrate, Pb(NO3)2, and potassium iodide, KI, react together to form a yellow
precipitate of lead iodide, PbI2, as well as potassium nitrate, KNO3.
Pb(NO3)2 + 2 KI  PbI2 + 2 KNO3
Calculate the mass of Pb(NO3)2 needed to produce 6.92 g of PbI2.