1
1
Ethanedioic acid, H2C2O4, forms crystals which are hydrated and have the formula
H2C2O4.xH2O.
P is a solution containing 9.45 g of H2C2O4.xH2O in 1.00 dm3 of solution.
Q is 0.150 mol / dm3 sodium hydroxide, NaOH.
You are to determine the value of x in the formula H2C2O4.xH2O by titrating Q with P.
(a) Put P into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of Q into a flask and titrate with P, using the
indicator provided.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of P used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of P required was ............... cm3.
Volume of Q used was ............... cm3.
[12]
© UCLES 2012
5070/31/M/J/12
For
Examiner’s
Use
2
(b) Q is 0.150 mol / dm3 sodium hydroxide.
Using your results from (a), calculate the concentration, in mol / dm3, of the ethanedioic
acid, H2C2O4, in P.
H2C2O4 + 2NaOH
For
Examiner’s
Use
Na2C2O4 + 2H2O
concentration of ethanedioic acid in P ...................................... mol / dm3 [2]
(c) Using your answer from (b), calculate the concentration, in g / dm3, of ethanedioic acid,
H2C2O4, in P.
[The relative formula mass of ethanedioic acid is 90.]
concentration of ethanedioic acid in P ...................................... g / dm3 [1]
(d) Using your answer from (c), calculate the mass of water in 9.45 g of hydrated ethanedioic
acid, H2C2O4.xH2O.
mass of water .............................................. g [1]
(e) Calculate the value of x in the formula H2C2O4.xH2O.
[The relative formula mass of H2O is 18.]
value of x ................................................. [2]
[Total: 18]
© UCLES 2012
5070/31/M/J/12
[Turn over
3
1
P is an aqueous solution prepared by reacting a metal oxide, MO, with an excess of
hydrochloric acid, HCl. In preparing P, 3.36 g of the metal oxide was completely reacted in
1.00 dm3 of 0.200 mol / dm3 hydrochloric acid, an excess.
MO + 2HCl
MCl 2 + H2O
You are to determine by titration the amount of acid remaining in P.
Q is 0.0640 mol / dm3 sodium hydroxide, NaOH.
(a) Put P into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of Q into a flask and titrate with P, using the
indicator provided.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of P used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of P required was ............................... cm3.
Volume of Q used was ............................... cm3.
[12]
© UCLES 2012
5070/31/O/N/12
For
Examiner’s
Use
4
(b) Q is 0.0640 mol / dm3 sodium hydroxide, NaOH.
Using your results from (a), calculate the concentration, in mol / dm3, of hydrochloric acid
in P.
NaOH + HCl
For
Examiner’s
Use
NaCl + H2O
concentration of hydrochloric acid in P ............................... mol / dm3 [2]
(c) Before reaction with the metal oxide, 1.00 dm3 of the acid contained 0.200 moles of
hydrochloric acid. Using your answer from (b), calculate the number of moles of acid
that reacted with 3.36 g of the metal oxide, MO.
moles of hydrochloric acid that reacted with the metal oxide ...............................[1]
(d) Using your answer to (c), deduce the number of moles of metal oxide, MO, that reacted
with the hydrochloric acid.
moles of metal oxide that reacted with the hydrochloric acid ...............................[1]
(e) Using your answer to (d) and the mass of metal oxide, 3.36 g, calculate the relative
atomic mass of the metal M in the metal oxide, MO.
[Relative atomic mass of oxygen, O, is 16.]
relative atomic mass of M ...............................[1]
[Total: 17]
© UCLES 2012
5070/31/O/N/12
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5
1
P is an aqueous solution prepared by reacting a metal carbonate, MCO3, with an excess
of dilute sulfuric acid, H2SO4. In preparing P, 5.04 g of the metal carbonate was completely
reacted in 1.00 dm3 of 0.100 mol / dm3 sulfuric acid, an excess.
MCO3 + H2SO4
MSO4 + H2O + CO2
You are to determine by titration the amount of acid remaining in P.
Q is 0.0800 mol / dm3 sodium hydroxide, NaOH.
(a) Put P into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of Q into a flask and titrate with P, using the
indicator provided.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of P used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of P required was ................... cm3.
Volume of Q used was ................... cm3.
[12]
© UCLES 2012
5070/32/O/N/12
For
Examiner’s
Use
6
(b) Q is 0.0800 mol / dm3 sodium hydroxide, NaOH.
Using your results from (a), calculate the concentration, in mol / dm3, of sulfuric acid
in P.
2NaOH + H2SO4
For
Examiner’s
Use
Na2SO4 + 2H2O
concentration of sulfuric acid in P .................................... mol / dm3 [2]
(c) Before reaction with the metal carbonate, 1.00 dm3 of the acid contained 0.100 mole
sulfuric acid. Using your answer from (b), calculate the number of moles of acid that
reacted with 5.04 g of the metal carbonate, MCO3.
moles of sulfuric acid that reacted with the metal carbonate ...................................... [1]
(d) Using your answer to (c), deduce the number of moles of metal carbonate, MCO3, that
reacted with the sulfuric acid.
moles of metal carbonate that reacted with the sulfuric acid ...................................... [1]
(e) Using your answer to (d) and the mass of metal carbonate, 5.04 g, calculate the relative
atomic mass of metal M in the metal carbonate, MCO3.
[Relative formula mass of carbonate, CO3, is 60.]
relative atomic mass of M .................................... [1]
[Total: 17]
© UCLES 2012
5070/32/O/N/12
[Turn over
7
1
A type of rust remover is an aqueous solution of phosphoric acid, H3PO4.
P is a solution prepared by taking 100 cm3 of this rust remover and diluting the solution by
adding distilled water until the total volume is 1.00 dm3.
The amount of phosphoric acid present in solution P can be determined by titrating a volume
of aqueous sodium hydroxide of known concentration with P, using an indicator.
Solution Q is 0.100 mol / dm3 sodium hydroxide.
(a) Put P into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of Q into a flask and titrate with P, using the
indicator provided.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of P used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of P required was ............... cm3.
Volume of solution Q used was ............... cm3.
[12]
© UCLES 2013
5070/31/M/J/13
For
Examiner’s
Use
8
(b) Q is 0.100 mol / dm3 sodium hydroxide.
Using your results from (a), calculate the number of moles of phosphoric acid, H3PO4,
in 1.00 dm3 of P.
2NaOH + H3PO4
For
Examiner’s
Use
Na2HPO4 + 2H2O
moles of phosphoric acid in 1.00 dm3 of P ................................................. [2]
(c) Calculate the mass, in grams, of phosphoric acid present in 100 cm3 of the rust remover.
The relative formula mass of phosphoric acid is 98.
mass of phosphoric acid present in 100 cm3 of rust remover .................................. g [1]
(d) Given that 1 cm3 of the rust remover has a mass of 1.03 g, calculate the percentage by
mass of phosphoric acid in the rust remover.
percentage by mass of phosphoric acid in the rust remover ..................................... [1]
[Total: 16]
© UCLES 2013
5070/31/M/J/13
[Turn over
9
1
P is an aqueous solution which contains a mixture of sodium carbonate, Na2CO3, and
sodium hydroxide, NaOH.
The concentration of sodium carbonate in P is 0.0200 mol / dm3.
You are to determine by titration the volume of dilute hydrochloric acid, Q, needed to
neutralise a volume of P, and then calculate the concentration of sodium hydroxide present.
Q is 0.200 mol / dm3 hydrochloric acid, HCl.
(a) Put Q into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of P into a flask and titrate with Q, using the
indicator provided.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of Q used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of Q required was ............................... cm3.
Volume of P used was ............................... cm3.
[12]
© UCLES 2013
5070/31/O/N/13
For
Examiner’s
Use
10
(b) Q is 0.200 mol / dm3 hydrochloric acid, HCl.
Calculate the number of moles of hydrochloric acid present in your average volume
of Q.
For
Examiner’s
Use
moles of hydrochloric acid present .............................................................................. [1]
(c) The concentration of sodium carbonate, Na2CO3, in P is 0.0200 mol / dm3.
Calculate the number of moles of sodium carbonate present in your volume of P.
moles of sodium carbonate present ............................................................................. [1]
(d) Using your answer to (c), deduce the number of moles of hydrochloric acid which react
with the sodium carbonate present in your volume of P.
Na2CO3 + 2HCl
2NaCl + H2O + CO2
moles of hydrochloric acid which react with the sodium carbonate ............................. [1]
(e) Using your answers to (b) and (d), calculate the number of moles of hydrochloric acid
which react with the sodium hydroxide in your volume of P.
moles of hydrochloric acid which react with the sodium hydroxide .............................. [1]
(f)
Using your answer to (e), calculate the concentration, in mol / dm3, of sodium hydroxide
in P.
NaOH + HCl
NaCl + H2O
concentration of sodium hydroxide in P ....................................................... mol / dm3 [1]
[Total: 17]
© UCLES 2013
5070/31/O/N/13
[Turn over
11
1
The amount of oxygen in a sample of air can be estimated by using the oxygen to produce iodine.
O2
+
4I–
+
4H+
2H2O
+
2I2
The amount of iodine produced by the above reaction can then be determined by titration with
sodium thiosulfate, Na2S2O3, using starch as an indicator.
2Na2S2O3
+
I2
Na2S4O6
+
2NaI
P is an aqueous solution of iodine produced by the reaction of all the oxygen in a sample of air.
Q is 0.100 mol / dm3 sodium thiosulfate.
(a) Put Q into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of P into a flask.
Add Q from the burette until the red-brown colour fades to pale yellow, then add a few drops
of the starch indicator. This will give a dark blue solution. Continue adding Q slowly from the
burette until one drop of Q causes the blue colour to disappear, leaving a colourless solution.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of Q used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of Q required was ................... cm3.
Volume of P used was ................... cm3.
© UCLES 2014
5070/31/O/N/14
[12]
12
(b) Q is 0.100 mol / dm3 sodium thiosulfate.
Using your results from (a), calculate the concentration, in mol / dm3, of iodine in P.
2Na2S2O3
+
I2
Na2S4O6
+
2NaI
concentration of iodine in P ......................................... mol / dm3 [2]
(c) Using your answer from (b), deduce the number of moles of oxygen required to produce the
iodine in 1.00 dm3 of P.
O2
+ 4I–
+
4H+
2H2O
+
2I2
moles of oxygen ...........................................................[1]
(d) Given that the number of moles of oxygen in your answer from (c) were present in 3.00 dm3
of air measured at room temperature and pressure, calculate the percentage by volume of
oxygen in this sample of air.
(One mole of gas occupies a volume of 24 dm3 at room temperature and pressure.)
percentage by volume of oxygen ...........................................................[2]
[Total: 17]
© UCLES 2014
5070/31/O/N/14
[Turn over
13
1
The active ingredient in bleaching powder is calcium hypochlorite, Ca(Cl O)2. When bleaching
powder is added to an acidified, aqueous solution of iodide ions, iodine is produced.
Ca(Cl O)2 +
4I–
4H+
+
CaCl 2
+
2H2O
+
2I2
The amount of iodine produced by the above reaction can be determined by titration with sodium
thiosulfate, Na2S2O3, using starch as an indicator.
2Na2S2O3
+
I2
Na2S4O6
+
2NaI
P is an aqueous solution of iodine produced by reacting bleaching powder with an excess of
acidified, aqueous iodide ions.
Q is 0.100 mol / dm3 sodium thiosulfate.
(a) Put Q into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of P into a flask.
Add Q from the burette until the red-brown colour fades to pale yellow, then add a few drops
of the starch indicator. This will give a dark blue solution. Continue adding Q slowly from the
burette until one drop of Q causes the blue colour to disappear, leaving a colourless solution.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of Q used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of Q required was ................... cm3.
Volume of P used was ................... cm3.
© UCLES 2014
5070/32/O/N/14
[12]
14
(b) Q is 0.100 mol / dm3 sodium thiosulfate.
Using your results from (a), calculate the concentration, in mol / dm3, of iodine in P.
2Na2S2O3
+
I2
Na2S4O6
+
2NaI
concentration of iodine in P ............................................ mol / dm3 [2]
(c) Using your answer from (b), deduce the number of moles of calcium hypochlorite required to
produce the iodine in 1 dm3 of P.
Ca(Cl O)2
+
4I– +
4H+
CaCl 2
+
2H2O
+
2I2
moles of calcium hypochlorite ............................................................ [1]
(d) Given that the number of moles of calcium hypochlorite in your answer from (c) were present
in 10.0 g of the bleaching powder, calculate the percentage by mass of calcium hypochlorite in
the bleaching powder.
[The relative formula mass of Ca(Cl O)2 is 143.]
percentage by mass of calcium hypochlorite in the bleaching powder
........................................................% [2]
[Total: 17]
© UCLES 2014
5070/32/O/N/14
[Turn over
15
1
An oxyacid of phosphorus has the formula H3PO3.
You are required to find by experiment the number of moles of sodium hydroxide that react with
1 mole of this acid.
P is 0.0984 mol / dm3 sodium hydroxide.
Q is an aqueous solution of the oxyacid of phosphorus, H3PO3, containing 5.04 g / dm3.
(a) Put Q into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of P into a flask and titrate with Q, using the indicator
provided.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of Q used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of Q required was ...................... cm3.
Volume of P used was ...................... cm3.
© UCLES 2015
5070/31/M/J/15
[12]
16
(b) P is 0.0984 mol / dm3 sodium hydroxide.
Calculate the number of moles of sodium hydroxide in the volume of P used.
moles of sodium hydroxide in the volume of P used ...........................................................[1]
(c) Q is an aqueous solution of H3PO3 containing 5.04 g / dm3.
Calculate the concentration, in mol / dm3, of H3PO3 in Q.
The relative formula mass of H3PO3 is 82.
concentration of H3PO3 in Q ............................................mol / dm3 [1]
(d) Calculate the number of moles of H3PO3 in the average volume of Q used in the titration.
moles of H3PO3 ...........................................................[1]
(e) Using your answers from (b) and (d), calculate the number of moles of sodium hydroxide
which react with 1 mole of H3PO3.
moles of sodium hydroxide ...........................................................[1]
(f)
Using your answer to (e), write an equation for the reaction of the oxyacid of phosphorus,
H3PO3, with sodium hydroxide.
...............................................................................................................................................[2]
[Total: 18]
© UCLES 2015
5070/31/M/J/15
[Turn over
17
1
Calcium carbonate tablets are often taken by people who have stomach pain caused by indigestion.
They work by neutralising acid in the stomach and are called antacid tablets.
P is an aqueous solution prepared by reacting two of the antacid tablets with an excess of
hydrochloric acid, HCl. In preparing P, all the calcium carbonate in the two tablets reacted when
they were added to 250 cm3 of 0.500 mol / dm3 hydrochloric acid, an excess.
CaCO3 + 2HCl
CaCl2 + H2O + CO2
You are to determine by titration the amount of acid remaining in P.
Q is 0.336 mol/dm3 sodium hydroxide, NaOH.
(a) Put P into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of Q into a flask and titrate with P, using the indicator
provided.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of P used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of P required was ...................... cm3.
Volume of Q used was ...................... cm3.
[12]
© UCLES 2015
5070/31/O/N/15
18
(b) Q is 0.336 mol / dm3 sodium hydroxide, NaOH.
Calculate the number of moles of sodium hydroxide in the volume of Q used.
moles of sodium hydroxide in the volume of Q used ...........................................................[1]
(c) Using the equation shown and your answer to (b), deduce the number of moles of
hydrochloric acid that reacted with the volume of Q used.
NaOH + HCl
NaCl + H2O
moles of hydrochloric acid that reacted with the volume of Q used ......................................[1]
(d) Using your answer to (c) and the average volume of P from the titration results, calculate the
number of moles of hydrochloric acid in 250 cm3 of P.
moles of hydrochloric acid in 250 cm3 of P ...........................................................[1]
(e) Calculate the number of moles of hydrochloric acid in 250 cm3 of 0.500 mol / dm3 hydrochloric
acid.
moles of hydrochloric acid in 250 cm3 of 0.500 mol / dm3 hydrochloric acid ..........................[1]
(f)
Using your answers from (d) and (e), calculate the number of moles of hydrochloric acid that
reacted with the calcium carbonate in the tablets.
moles of hydrochloric acid that reacted with calcium carbonate ...........................................[1]
(g) Using your answer to (f), calculate the mass of calcium carbonate in one tablet of the antacid.
The relative formula mass of calcium carbonate is 100.
mass of calcium carbonate in one tablet of the antacid ................................................... g [2]
[Total: 19]
© UCLES 2015
5070/31/O/N/15
[Turn over
19
1
Milk of magnesia is a suspension of insoluble magnesium hydroxide in water. It is taken by people
who have stomach pain caused by indigestion and works by neutralising acid in the stomach.
P is an aqueous solution of volume 110 cm3 prepared by reacting 10.0 cm3 of milk of magnesia with
an excess of hydrochloric acid, HCl. In preparing P, all the magnesium hydroxide in the 10.0 cm3 of
suspension reacted when it was added to 100 cm3 of 1.00 mol / dm3 hydrochloric acid, an excess.
Mg(OH)2 + 2HCl
MgCl2 + 2H2O
You are to determine by titration the amount of acid remaining in P.
Q is 0.527 mol / dm3 sodium hydroxide, NaOH.
(a) Put P into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of Q into a flask and titrate with P, using the indicator
provided.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of P used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of P required was ...................... cm3.
Volume of Q used was ...................... cm3.
[12]
© UCLES 2015
5070/32/O/N/15
20
(b) Q is 0.527 mol / dm3 sodium hydroxide, NaOH.
Calculate the number of moles of sodium hydroxide in the volume of Q used.
moles of sodium hydroxide in the volume of Q used ...........................................................[1]
(c) Using the equation shown and your answer to (b), deduce the number of moles of
hydrochloric acid that reacted with the volume of Q used.
NaOH + HCl
NaCl + H2O
moles of hydrochloric acid that reacted with the volume of Q used ......................................[1]
(d) Using your answer to (c) and the average volume of P from the titration results, calculate the
number of moles of hydrochloric acid in 110 cm3 of P.
moles of hydrochloric acid in 110 cm3 of P ...........................................................[1]
(e) Calculate the number of moles of hydrochloric acid in 100 cm3 of 1.00 mol / dm3 hydrochloric
acid.
moles of hydrochloric acid in 100 cm3 of 1.00 mol / dm3 hydrochloric acid ............................[1]
(f)
Using your answers from (d) and (e), calculate the number of moles of hydrochloric acid that
reacted with the magnesium hydroxide in the milk of magnesia.
moles of hydrochloric acid that reacted with magnesium hydroxide .....................................[1]
(g) Using your answer to (f), calculate the concentration of magnesium hydroxide in milk of
magnesia in g / dm3.
The relative formula mass of magnesium hydroxide is 58.
concentration of magnesium hydroxide in milk of magnesia ................................... g / dm3 [2]
[Total: 19]
© UCLES 2015
5070/32/O/N/15
[Turn over
21
1
Sodium percarbonate is often used to remove stains from clothing. It is a white solid with the
formula Na2CO3.xH2O2. When the solid dissolves in water, it produces a solution containing
sodium carbonate and hydrogen peroxide.
P is a solution containing 7.85 g of Na2CO3.xH2O2 in 1.00 dm3 of solution.
Q is 0.100 mol / dm3 hydrochloric acid.
You are to determine the value of x in the formula Na2CO3.xH2O2 by titrating the sodium carbonate
in P with Q.
Na2CO3 + 2HCl
2NaCl + H2O + CO2
(a) Put Q into the burette.
Pipette a 25.0 cm3 (or 20.0 cm3) portion of P into a flask and titrate with Q, using the indicator
provided.
Record your results in the table, repeating the titration as many times as you consider
necessary to achieve consistent results.
Results
Burette readings
titration number
1
2
final reading / cm3
initial reading / cm3
volume of Q used / cm3
best titration results (✓)
Summary
Tick (✓) the best titration results.
Using these results, the average volume of Q required was ........................... cm3.
Volume of solution P used was ........................... cm3.
© UCLES 2016
5070/31/M/J/16
[12]
22
(b) Q is 0.100 mol / dm3 hydrochloric acid.
Using your results from (a), calculate the concentration, in mol / dm3, of sodium carbonate in
P. Give your answer to three significant figures.
concentration of sodium carbonate in P .......................................... mol / dm3 [2]
(c) Using your answer from (b), calculate the concentration, in g / dm3, of sodium carbonate in P.
[The relative formula mass of sodium carbonate is 106.]
concentration of sodium carbonate in P .............................................. g / dm3 [1]
(d) Using your answer from (c), calculate the mass of hydrogen peroxide in 7.85 g of
sodium percarbonate.
mass of hydrogen peroxide ....................................................... g [1]
(e) Calculate the value of x in the formula Na2CO3.xH2O2.
[The relative formula mass of H2O2 is 34.]
The value of x is .......................................................... [2]
[Total:18]
© UCLES 2016
5070/31/M/J/16
[Turn over