Q1.
(a)     A student used the apparatus in the figure below to do a titration.
 
(i)      What is the name of the piece of apparatus labelled A?
Draw a ring around the correct answer.
 
burette	measuring cylinder	test tube	
(1)
(ii)     What should the student add to the acid in the conical flask?
Draw a ring around the correct answer.
 
catalyst	indicator	water	
(1)
(iii)    What would the student see when the end point of the titration has been reached?
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(1)

(b)     The student does the titration three times.
(i)      State one variable that the student needs to keep the same to make it a fair test.
______________________________________________________________
(1)
(ii)     The student’s results are shown in the table below.
 
Titration	Volume of sodium hydroxide solution 
added in cm3	
1	22.40	
2	22.20	
3	22.30	
Calculate the mean volume of sodium hydroxide solution added.
______________________ cm3
(1)
(Total 5 marks)
Q2.
The table shows some information about acids and alkalis.
 
Name of acid 
or alkali	Type	Ions produced in 
solution	pH	Effect on Universal 
Indicator	
Hydrochloric acid	Strong acid	H+	Cl–	1	Goes red	
Sodium hydroxide	Strong alkali	Na+	OH–	13	Goes purple	
Use the information in the table to help you answer parts (a) and (b).
(a)     Draw a ring around the correct answer to complete each sentence.
(i)     Hydrochloric acid is acidic.
 
 	 	Cl-	 	
 	This is because it contains	H+	ions	
 	 	OH-	 	
(1)

(ii)    Sodium hydroxide solution is alkaline.
 
 	 	H+	 	
 	This is because it contains	Na+	ions	
 	 	OH-	 	
(1)
 
 	 	 	higher than	 	
 	(iii)	The pH of acids is	lower than	the pH of alkalis.	
 	 	 	the same as	 	
(1)
(b)     Ethanoic acid is a weak acid.
Universal Indicator can be used to show that hydrochloric acid is a stronger acid than ethanoic acid of the same concentration.
Explain how.
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(2)
(c)     Draw a ring around the correct answer to complete this sentence.
 
 	completely	 	
Strong acids and strong alkalis are	not	ionised in water.	
 	partially	 	
(1)
(d)    The diagram shows the apparatus used to find the volume of hydrochloric acid that reacts with 25.0 cm3 of sodium hydroxide solution.
 
(i)      Which one of the following is the correct name for A?
Draw a ring around your answer.
 
beaker	conical flask	pipette	
(1)
(ii)      Use the correct word from the box to complete the sentence.
 
distillation	filtration	titration	
The method used to find the volume of acid that reacts with a known volume
of alkali is __________________________________ .
(1)
(iii)     Suggest one way to make the results more reliable.
______________________________________________________________
(1)
(Total 9 marks)

Q3.
In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
A student used the equipment shown to do a titration.
 
Describe how the student should use this equipment to find the volume of sodium hydroxide solution that reacts with a known volume of acid.
Include any measurements the student should make.
Do not describe how to do any calculations.
_______________________________________________________________________
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(Total 6 marks)
Q4.
This label has been taken from a bottle of household ammonia solution.
 
          Household ammonia is a dilute solution of ammonia in water. It is commonly used to remove grease from ovens and windows.
(a)     The amount of ammonia in household ammonia can be found by titration.
          25.0 cm3 of household ammonia is placed in a conical flask. Describe how the volume of dilute nitric acid required to neutralise this amount of household ammonia can be found accurately by titration. Name any other apparatus and materials used.
          To gain full marks you should write down your ideas in good English. Put them into a sensible order and use correct scientific words.
___________________________________________________________________
___________________________________________________________________
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(4)
(b)     In an experiment, it was found that 25.0 cm3 of household ammonia was neutralised by 20.0 cm3 of dilute nitric acid with a concentration of 0.25 moles per cubic decimetre.
          The balanced symbol equation which represents this reaction is
NH3(aq)  +  HNO3(aq)  →  NH4NO3(aq)
          Calculate the concentration of the ammonia in this household ammonia in moles per cubic decimetre.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Concentration = _______________ moles per cubic decimetre
(2)
(c)     The salt, ammonium nitrate, is formed in this reaction.
          Describe, and give the result of, a chemical test which shows that ammonium nitrate contains ammonium ions.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
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(2)
(Total 8 marks)

Q5.
(a)     The table gives information about two isotopes of hydrogen, hydrogen-1 and hydrogen-2.
 
 	Hydrogen-1	Hydrogen-2	
Atomic number	1	1	
Mass number	1	2	
An atom of hydrogen-1 is represented as: 

Show how an atom of hydrogen-2 is represented.	 	
 	 	
(1)
(b)     (i)      Calculate the relative formula mass (Mr) of water, H2O
Relative atomic masses: H = 1; O = 16.
______________________________________________________________
______________________________________________________________
Relative formula mass (Mr ) = ______________________
(1)
(ii)     Simple molecules like water have low boiling points.
Explain why, in terms of molecules.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)

(c)     Molecules of heavy water contain two atoms of hydrogen-2 instead of two atoms of hydrogen-1.
Explain why a molecule of heavy water has more mass than a normal water molecule.
You should refer to the particles in the nucleus of the two different hydrogen atoms in your answer.
___________________________________________________________________
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(2)
(Total 6 marks)
Q6.
Potable water is water that is safe to drink.
Seawater can be changed into potable water by desalination.
(a)     Name the substance removed from seawater by desalination.
___________________________________________________________________
(1)
(b)     Desalination requires large amounts of energy.
Desalination is only used when there is no other source of potable water.
Give one reason why.
___________________________________________________________________
___________________________________________________________________
(1)
Water from lakes and rivers can be treated to make it potable.
(c)     The first stage is to filter the water from lakes and rivers.
Why is the water filtered?
___________________________________________________________________
___________________________________________________________________
(1)

(d)     Chlorine gas is then added to the filtered water.
Why is chlorine gas used to treat water?
___________________________________________________________________
___________________________________________________________________
(1)
(e)     Describe a test for chlorine gas.
Give the result of the test if chlorine is present.
Test ______________________________________________________________
Result ____________________________________________________________
(2)
Some students investigated different water samples.
The table shows some of their results.
 
Water	pH	Mass of dissolved solid in g / dm3	
Tap water	6.5	0.5	
Seawater	8.1	35.0	
Pure water	 	 	
(f)      Complete the table above to show the expected results for pure water.
(2)
(g)     What mass of dissolved solid is present in 100 cm 3 of the sample of tap water?
Tick (✔) one box.
 
0.05 g		
0.5 g		
5 g		
50 g		
(1)

(h)     Boiling points can be used to show whether substances are pure.
The diagram shows the apparatus the students used to find the boiling point of tap water.
 
The students made a mistake setting up the apparatus.
What mistake did the students make?
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___________________________________________________________________
(1)
(Total 10 marks)

Mark schemes
Q1.
(a)     (i)      burette
1
(ii)     indicator
1
(iii)    colour change
1
(b)     (i)      any one from:
•        volume of (hydrochloric) acid
allow amount of (hydrochloric) acid
•        concentration of (hydrochloric) acid
•        concentration of (sodium) hydroxide
allow concentration of alkali
1
(ii)     22.3(0)
1
[5]
Q2.
(a)      (i)     H+
1
(ii)     OH–
1
(iii)    lower than
1
(b)     with HCl:
UI goes red / pink
allow a comparison eg redder than ethanoic acid
1
has a pH 0 ,1 ,2 or 3
allow a comparison eg has pH less than ethanoic acid.
do not accept an incorrect pH.
or
with ethanoic acid:
UI goes orange / yellow (1)
allow a comparison with HCl
has a pH 4 / or above (but less than 7) (1)
allow a comparison with HCl
1
(c)     completely
1
(d)     (i)      conical flask
1
(ii)     titration
1
(iii)    repeat
allow compare with another students results
or
take average
1
[9]
Q3.
Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. Examiners should also refer to the information in the Marking guidance.
0 marks
No relevant content.
Level 1 (1-2 marks)
There is a simple description of using some of the equipment.
Level 2 (3-4 marks)
There is a description of an experimental method involving a measurement, or including addition of alkali to acid (or vice versa).
Level 3 (5-6 marks)
There is a description of a titration that would allow a successful result to be obtained.
Examples of chemistry points made in the response could include:
•         acid in (conical) flask
•         volume of acid measured using pipette
•         indicator in (conical) flask
•         sodium hydroxide in burette
•         white tile under flask
•         slow addition
•         swirling
•         colour change
•         volume of sodium hydroxide added
Extra information
•        allow acid in the burette to be added to sodium hydroxide in the (conical) flask
•        allow any specified indicator
colour change need not be specified
[6]
Q4.
(a)     
must be a description of a titration no titration = 0 marks
Quality of written communication
for correct sequencing of 2 of first 3 bullet points  i.e. 1 + 2
or 2 + 3 or 1 + 3
1
any three from:
•        nitric acid in burette
do not accept biuret 
can be inferred from 3rd point
•        add nitric acid until indicator changes (colour)
can be named acid-base indicator
colour change does not have to be correct
•        note (burette) volume used or final  reading
•        accuracy: e.g. repeat
accept white tile or dropwise near end or white background or swirling the flask or read meniscus at eye level
3
(b)     e.g. formula method:
25 × MNH3 = 0.25 × 20
1
MNH3 = 0.2
correct answer alone = 2
OR
moles NH3 = moles HNO3
=  × 0.25 = 0.005 moles (1)
concentration NH3 
=  = 0.2 (1)
1
(c)     sodium hydroxide or potassium hydroxide or lithium hydroxide or calcium
hydroxide
ignore mention of alkali
1
ammonia produced
accept gas produced turns (damp) (red) litmus blue (not blue litmus) or alkaline gas produced
any suitable named indicator e.g. UI with consequential marking white fumes / smoke with (concentrated) HCl
do not accept white gas wrong test = 0 marks
1
[8]
Q5.
(a)    
 
2 and 1 must be on the left
2 must be above half-way on the H and the 1 below half-way
accept diagram with 2 different particles in centre and 1 particle on circle
1
(b)     (i)      18
ignore working
ignore units
1
(ii)     forces (of attraction) between molecules or
bonding between molecules or
intermolecular forces /intermolecular bonds
1
are weak or not much energy needed to break them or easily overcome
must be linked to first mark
if no other mark awarded allow small molecules / small Mr for 1 mark
allow forces / bonds are weak for 1 mark
do not allow covalent bonding is weak
1
(c)                          any reference to more protons = 0 marks
H-2 atoms have 1 proton and 1 neutron
allow H-2 has more neutrons / particles for 1 mark
1
H-1 atoms have one proton
allow H-2 has two particles and H-1 has one particle for 1 mark
or
H-2 atom has one neutron (1)
allow H-2 atom has one more neutron for 2 marks
H-1 atom has no neutrons (1)
NB heavy water (molecule) has 2 more neutrons = 2 marks
heavy water (molecule) has more neutrons / particles = 1 mark
if no other mark awarded then heavy water molecule has Mr of 20 = 1 mark
ignore reference to electrons
1
[6]
Q6.
(a)     sodium chloride
or
salt
allow dissolved salts
1
(b)     expensive
1
(c)     to remove solids
1
(d)     to sterilise the water
allow to kill microorganisms
1
(e)     test: (damp) litmus paper
1
result: bleached
or
turns white
1
(f)      pH: 7.0
1
mass of dissolved solid: 0.0 (g)
1
(g)     0.05 g
1
(h)     did not immerse the thermometer (bulb)
1
[10]