Q1. When a metal carbonate reacts with an acid, a salt, carbon dioxide and water are produced.
(a)  Describe how you would test for carbon dioxide gas.
Test _______________________________________________________________
___________________________________________________________________
Result _____________________________________________________________
___________________________________________________________________
(2)
(b)  Describe how to make pure dry crystals of magnesium chloride from magnesium carbonate and a dilute acid.
In your method you should name the apparatus and reagents you plan to use.
___________________________________________________________________
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___________________________________________________________________
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(6)
(Total 8 marks)

Q2. A student was trying to produce hydrogen gas.
Figure 1 shows the apparatus she used.
Figure 1
 
(a)     No gas was produced.
The student’s teacher said that this was because the substances in the flask did not react.
(i)      Suggest why the substances in the flask did not react.
______________________________________________________________
______________________________________________________________
______________________________________________________________
(1)
(ii)     Which two substances could the student have put in the flask to produce hydrogen safely?
Tick (✓) one box.
Gold and dilute hydrochloric acid		
Potassium and dilute hydrochloric acid		
Zinc and dilute hydrochloric acid		
(1)

(b)     Another student did produce hydrogen from two substances.
Figure 2 shows the apparatus the student used to collect and measure the volume of the hydrogen gas.
Figure 2

Give the name of the apparatus labelled X.
___________________________________________________________________
(1)
(c)     The student did the experiment four times. Her results are shown in the table below.
 
Experiment	Volume of hydrogen collected in one minute in cm3	
1	49	
2	50	
3	35	
4	48	
(i)      One of the results is anomalous.
Which result is anomalous? Write your answer in the box.    
Give a reason for your choice.
______________________________________________________________
(2)
(ii)     Calculate the mean volume of hydrogen collected in one minute.
______________________________________________________________
______________________________________________________________
Mean volume = ____________________ cm3
(2)
(iii)    Give a reason why the experiment should be repeated several times.
______________________________________________________________
______________________________________________________________
______________________________________________________________
(1)
(d)     A teacher collected two tubes full of hydrogen gas, as shown in Figure 3.
Figure 3
 
She tested tube A with a lighted splint as soon as she took the bung out.
She tested tube B with a lighted splint a few seconds after taking the bung out.
(i)      Suggest why tube B gave a much louder pop than tube A.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(1)
(ii)     Complete and balance the chemical equation for the reaction that takes place when the hydrogen reacts in this test.
H2    +    O2  
(2)
(Total 11 marks)
Q3.A student was investigating the reaction of lithium and water.
She added a few drops of universal indicator to water in a trough and added a piece of lithium.
 
The word equation for the reaction is:
lithium + water        lithium hydroxide + hydrogen
(a)     (i)      The lithium floated on the water.
State two other observations that the student would see during the reaction.
1. ____________________________________________________________
2. ____________________________________________________________
(2)
(ii)     Balance the symbol equation for the reaction of lithium and water.
2 Li(s)  +  _____ H2O(l)      _____  LiOH(aq)  +  H2(g)
(2)
(iii)    Describe a simple test and the result that would show the gas was hydrogen.
______________________________________________________________
______________________________________________________________
(1)
(iv)     All Group 1 metals have similar reactions with water.
State why, in terms of electronic structure.
______________________________________________________________
______________________________________________________________
(1)
(b)     Lithium and other Group 1 metals have different properties from the transition metals.
Tick (✔) two properties that are properties of Group 1 metals.
They react with oxygen.		
They form coloured compounds.		
They are strong and hard.		
They have low melting points.		
(2)

(c)     The electronic structure of a potassium atom is 2, 8, 8, 1
(i)      Draw a diagram to show the electronic structure of a potassium ion.
Show the charge on the potassium ion.

 

 
 
(2)
(ii)     Potassium is more reactive than sodium.
Explain why, in terms of electronic structure.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(3)
Q4.Hydrogen peroxide, H2O2, is often used as a bleach. It decomposes forming water and oxygen.
          (a)     (i)      Write the balanced chemical equation for the decomposition of hydrogen peroxide.
______________________________________________________________
(3)
(ii)     Give a test for oxygen.
Test _________________________________________________________
Result of test __________________________________________________
______________________________________________________________
(2)
(b)     The rate of decomposition of hydrogen peroxide at room temperature is very slow. Manganese oxide is a catalyst which can be used to speed up the decomposition. Complete the sentence.
A catalyst is a substance which speeds up a chemical reaction. At the end of the reaction, the catalyst is ________________________________________________
(1)
(c)     Two experiments were carried out to test if the amount of manganese oxide, MnO2 affected the rate at which the hydrogen peroxide decomposed.
(i)      Complete the diagram to show how you could measure the volume of oxygen formed during the decomposition.
 
(2)
(ii)     The results are shown in the table.       Draw a graph of these results. The graph for 0.25 g MnO2 has been drawn for you.
 
Time in minutes	0	0.5	1	1.5	2	2.5	3	3.5	
Volume of gas in cm3
using 0.25 g MnO2	0	29	55	77	98	116	132	144	
Volume of gas in cm3
using 2.5 g MnO2	0	45	84	118	145	162	174	182	
 
(3)
(iii)     Explain why the slopes of the graphs become less steep during the reaction.
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(iv)    The same volume and concentration of hydrogen peroxide solution was used for both experiments. What two other factors must be kept the same to make it a fair test?
1. ____________________________________________________________
______________________________________________________________
2. ____________________________________________________________
______________________________________________________________
(2)
(Total 15 marks)
Q5.Many sea creatures have shells containing calcium carbonate.
 
(a)     The seas are becoming more acidic.
Suggest and explain how acids affect the shells of sea creatures.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
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(2)
(b)     A student investigated the effect of heating calcium carbonate.
 
(i)      The symbol equation for the chemical reaction that occurs when calcium carbonate is heated is:
                                   CaCO3        →        CaO        +         CO2
Complete the word equation for the reaction.
______________________  →  ______________________  +  carbon dioxide
(1)
(ii)     50 g of CaCO3 produced 28 g of CaO.
What mass of CO2 was produced?
______________________________________________________________
____________________ g
(1)
(iii)    When carbon dioxide passed through the solution in test tube B, the solution became cloudy.
Name the solution.
______________________________________________________________
(1)
(Total 5 marks)

Mark schemes
Q1.
(a)  limewater
allow calcium hydroxide solution
1
(which) turns cloudy / milky (when carbon dioxide is added)
must link to limewater
1
(b)  Level 3: The method would lead to the production of a valid outcome. All key steps are identified and logically sequenced.
5−6
Level 2: The method would not necessarily lead to a valid outcome. Most steps are identified, but the method is not fully logically sequenced.
3−4
Level 1: The method would not lead to a valid outcome. Some relevant steps are identified, but links are not made clear.
1−2
No relevant content
0
Indicative content
•   use hydrochloric acid
•   place acid in suitable container e.g. beaker
•   add (a spatula of) magnesium carbonate
•   stir
•   continue adding magnesium carbonate until in excess
•   when solid remains or no more effervescence occurs
•   filter to remove excess magnesium carbonate
•   using filter paper and funnel
•   pour solution into evaporating dish
•   evaporate water till crystallisation point reached
•   using electric heater or Bunsen burner and a water bath
•   leave to cool
•   until crystals form
•   pour off excess water or filter
•   dry crystals in cool oven or with filter paper
[8]
Q2.
(a)     (i)      copper is less reactive than hydrogen or copper is unreactive
1
(ii)     Zinc and dilute hydrochloric acid
1
(b)     (gas) syringe
1
(c)     (i)      35
allow 3
1
because not close to others
accept it is much lower than the others
ignore references to trends or patterns
dependent on the first mark
1
(ii)     (49 + 50 + 48) / 3
= 49
correct answer with or without working gains 2 marks
1
allow ecf from anomaly identified in (i) for 2 marks:
      •      Exp 1 anomalous gives 43.3
      •      Exp. 2 anomalous gives 44
      •      Exp. 4 anomalous gives 44.7
answer of 45.5 or 46 (anomaly not excluded) gains 1 mark
correct working excluding anomaly but with wrong answer gains 1 mark
1
(iii)    so that a mean can be calculated
accept improves accuracy of the mean or so anomalies can be identified / discarded or to reduce effect of random errors
ignore makes it a fair test
ignore reliability, validity, repeatability, reproducibility
1
(d)     (i)      idea of mixing with oxygen / air, letting air / oxygen in
accept converse
1
(ii)     H2O
do not accept incorrect additional products
1
balancing 2 … (1) … 2
allow fractions or multiples
dependent on first mark
1
[11]
Q3.
(a)     (i)      any two from:
•        bubbles / effervescence / fizzing
ignore hydrogen / gas produced
•        lithium disappears / gets smaller
allow dissolves
do not allow melts / burns
•        lithium moves on the surface of the water
ignore floats
•        (universal indicator) turns blue / purple
2
(ii)     2
left-hand side correct
1
2
right-hand side correct
allow multiples for full credit
1
(iii)    light / burn, which will give a (squeaky) pop / explosion
1
(iv)    all have 1 electron in their outer shell / energy level
allow have the same number of electrons in their outer shell / energy level
1
(b)     They react with oxygen
1
They have low melting points
1
(c)     (i)      electronic structure [2,8,8] is drawn
incomplete inner shells scores a maximum of 1 mark
1
charge is +
allow [2,8,8]+ for 1 mark
1
(ii)     because (in potassium) the outer shell electron is further away from the nucleus or because potassium atoms are larger than sodium atoms
it should be clear that the candidate is referring to the outer shell electron: if this is not clear a maximum of 2 marks can be awarded
1
therefore the outer shell electron is less strongly attracted to the nucleus or is more shielded from the attraction of the nucleus and so the outer shell electron in potassium is more easily lost
1
3 marks can be scored for answering the question in terms of sodium
1
[13]
Q4.
(a)     (i)      H2O2 reactant correct
ignore any state symbols
1
H2O + O2 products correct
1
2H2O2 → 2H2O + O2 balanced
accept correct multiple
1
(ii)     glowing splint
1
relights
accept ‘bursts into flame’
do not accept a lighted splint burns brighter or faster
1
(b)     unchanged
accept not used up or left (behind)
1
          (c)     (i)      gas syringe or measuring cylinder either with scale drawn or labelled
1
the apparatus as drawn would work
1
(ii)     correct plotting of points
one mark to be deducted for each error
2
         best fit graph line drawn (single line drawn)
1
(iii)     concentration of hydrogen peroxide
decreases
accept less particles of hydrogen peroxide to collide
do not accept hydrogen peroxide gets used up
1
rate of reaction decreases
accept reaction gets slower
1
(iv)    any two from:
•        temperature
•        pressure
•        division of catalyst or manganese oxide
do not accept any other factors
2
[15]
Q5.
(a)     (acids) react with calcium carbonate / shells
1
(so) shells will be (chemically) eroded
do not allow melts
allow dissolved / are thinner / worn away / corroded
ignore weakened / break down
1
(b)     (i)      calcium carbonate → calcium oxide (+ carbon dioxide)
ignore numbers and symbols
1
(ii)     22 (g)
mark answer line and ignore working
1
(iii)    calcium hydroxide / limewater
ignore solution
1
[5]