Chemistry GCSE

1
Chemistry GCSE

• Revision Questions

2
What name is given to a reaction which gives out
heat?
3
Exothermic (endothermic reactions take in heat)
4
What is an igneous rock?
5
Igneous rock is formed from solidified magma
(molten rock).
6
Describe a test for alkenes.
7
Alkenes decolourise bromine water
8
What two elements form ammonia?
9
nitrogen and hydrogen.
10
What type of reaction is characterised by the
gain of electrons?
11
reductionoxidation is the loss of electrons.
12
A student studied the reaction between dilute
hydrochloric acid and an excess of copper
carbonate copper carbonate hydrochloric acid ?
copper chloride water carbon dioxide The
student measured the mass loss during a given
time. The results are shown in the table below

• Plot the mass lost against time on the grid
  below. (3marks)

0.6 0.5 0.4 0.3 0.2 0.1 0
Mass in g
0 1 2
3 4 5 6
Time in minutes
(b) After how many minutes had all the acid been
used up? .........................................
..... Minutes (1 mark) (c) A second experiment
was carried out at a higher temperature. All
other factors were the same. Draw a line on the
graph above to show the results that you would
expect. (2 marks)
13
A student studied the reaction between dilute
hydrochloric acid and an excess of copper
carbonate copper carbonate hydrochloric acid ?
copper chloride water carbon dioxide The
student measured the mass loss during a given
time. The results are shown in the table below

• Plot the mass lost against time on the grid
  below. (3marks)

Mark each point clearly with a dot or cross. This
will gain 2 marks. Draw the best fit line
smoothly ignoring any anomalous points. As no
mass is lost the line should go through
(0,0). The second graph must have a steeper slope
but the same maximum. Dont forget to label your
new graph.
Mass in g
0 1 2
3 4 5 6
Time in minutes
(b) After how many minutes had all the acid been
used up? ........4.7..............................
...... Minutes (1 mark) (c) A second
experiment was carried out at a higher
temperature. All other factors were the same.
Draw a line on the graph above to show the
results that you would expect. (2 marks)
14
The Ablonian 1 Drona coin is made of an alloy of
zinc, silver and copper. The bar chart shows the
mass of each metal in a 200g bar of this alloy..
(a) (i) Calculate the percentage of copper, in
the coins. .......................................
..................................................
....................................... ..........
..................................................
..................................................
.........(1 mark) (ii) The Drona coin has a mass
of 8 grams. Calculate the mass of copper in this
coin. ............................................
..................................................
.......................................... .......
..................................................
..................................................
............................. Mass of copper
........................................ g
(2
marks) (b) Many metals can be extracted by
removing oxygen from their ores. (i) What name is
given to a reaction in which oxygen is removed
from a substance? ................................
..................................................
.......................................(1
mark) (ii) Which metal in the coin cannot be
extracted from its ore in this way? Explain your
answer. ..........................................
..................................................
............................................ .....
..................................................
..................................................
............................... ..................
..................................................
..................................................
..................

(2 marks)
15
The Ablonian 1 Drona coin is made of an alloy of
zinc, silver and copper. The bar chart shows the
mass of each metal in a 200g bar of this alloy..
(a) (i) Calculate the percentage of Copper, in
the coins. .............160 200 x100 80
..................................................
......................... .(1 mark) (ii) The
Drona coin has a mass of 8 grams. Calculate the
mass of copper in this coin. .....................
.........8x80100............1 mark. .for just
the working 2 marks for the correct
answer ...........................................
..................................................
........................................... Mass
of copper ...................... 6.4
.................. g
(2 marks) (b) Many metals can
be extracted by removing oxygen from their
ores. (i) What name is given to a reaction in
which oxygen is removed from a substance? ........
.......................................
Reduction ........................................
.......................(1 mark) (ii) Which metal
in the coin cannot be extracted from its ore in
this way? Explain your answer. ........ Silver
because silver is less reactive than carbon
.................................................
Remember if the question says explain you need to
have a because in your answer. .................
..................................................
..................................................
....(2 marks)
16
Crude oil is a mixture of many hydrocarbons. The
diagram shows the method used to separate crude
oil.
(a) Name this method of separating crude
oil. .............................................
..................................................
............... (1 mark) (b) Crude oil contains
hydrocarbon molecules of different sizes. Which
of the fractions contains the largest hydrocarbon
molecules? .......................................
..................................................
.................... (1 mark) (c) The fuel gas
fraction includes the hydrocarbon methane, CH4.
Name the group of hydrocarbons which includes
methane and ethane.
.. (1 mark) (d) More of the fuel fraction is
obtained than can be used. Some of it is cracked
to produce more useful products. Describe as
fully as you can the process of
cracking.


.. (3 marks)
17
Crude oil is a mixture of many hydrocarbons. The
diagram shows the method used to separate crude
oil.
(a) Name this method of separating crude
oil. ............... fractional distillation
..................................................
............................ (1 mark) (b) Crude
oil contains hydrocarbon molecules of different
sizes. Which of the fractions contains the
largest hydrocarbon molecules? ................
bitumen ..........................................
..................................................
. (1 mark) (c) The fuel gas fraction includes the
hydrocarbon methane, CH4. Name the group of
hydrocarbons which includes methane and
ethane. alkanes ..
(1 mark) (d) More of the fuel fraction is
obtained than can be used. Some of it is cracked
to produce more useful products. Describe as
fully as you can the process of cracking. Long
chain hydrocarbons can be broken into down into
smaller chains (1mark) by passing the vapour over
a heated catalyst (1 mark). This process is
called thermal decomposition(1 mark)
Alkenes/cc/double bonds are formed. (1mark).
Note that although there are only 3 marks for
this question there are four permitted answers
you only have to give three of them to get full
marks.
18
Below is part of a periodic table
a) Which of antimony (Sb) or Tellurium (Te) is
most likely to be a metal?
.(1 mark) b) Use your knowledge of
trends in the periodic table to complete the
following table.

(3 marks)
c) Most of the elements in the periodic table are
arranged according to their mass. However
potassium, K, and argon, Ar, have atomic masses
39 and 40 respectively. Why are they apparently
placed in the wrong order ?

.(2 marks)
19
Below is part of a periodic table
a) Which of antimony (Sb) or Tellurium (Te) is
most likely to be a metal? Sb
.(1 mark) b) Use your knowledge of
trends in the periodic table to complete the
following table.

(3 marks)
c) Most of the elements in the periodic table are
arranged according to their mass. However
potassium, K, and argon, Ar, have atomic masses
39 and 40 respectively. Why are they apparently
placed in the wrong order ? Both elements are in
groups of elements with similar chemical
properties (1 mark) Elements in the periodic
table are arranged according to increasing atomic
number or proton number (1 mark)
20
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22
The table below shows some bond energies.

• Methane burns in oxygen according to the
  following equation
• CH4 2O2 ? CO2 2H2O
• Calculate the energy change which takes place
  when one mole of methane is completely burned in
  oxygen.
• ...............
  ....................................
• ...............
  ....................................
• ...............
  ...................................
• ..................................................
  ..................................................
  .................................................
  ......................
• ..................................................
  ..................................................
  ..................................................
  ..........(3 marks)
• b) Is the reaction between methane and oxygen
  endothermic or exothermic. Give your reasons.
• ..................................................
  ..................................................
  ..................................................
  .........................
• ..................................................
  ..................................................
  ..................................................
  .............(2 marks)
• C) Suggest a use of methane gas.
• ..................................................
  ..................................................
  ..................................................
  .............(1 mark)

23
The table below shows some bond energies.

• Methane burns in oxygen according to the
  following equation
• CH4 2O2 ? CO2 2H2O
• Calculate the energy change which takes place
  when one mole of methane is completely burned in
  oxygen.
• 4 x (C-H) 2 x (OO) 2 x (CO) 4 x (O-H)
  .....................................
  ..........
• 4 x(413) 2 x (497) 2 x (740) 4 x (463)
  .....................................
  ..............
• 1652 994-1480-1852
  ................................
• ............. -685 kJ/mol ........................
  ..................................................
  ..................................................
  ..................
• Remember reactants products and include units
  ..................................................
  ..........................(3 marks)
• b) Is the reaction between methane and oxygen
  endothermic or exothermic. Give your reasons.
• Exothermic because heat is given out, or because
  the energy change is negative ....................
  ............. (2 marks)
• c) Suggest a use of methane gas.
• As a fuel ........................................
  ..................................................
  ..................................................
  ......(1 mark)

24
Hydrogen bromide (HBr) can be made by the
reaction of hydrogen (H2) with bromine
(Br2). (a) The diagrams represent the
outer energy levels of hydrogen and bromine
atoms. Draw a similar diagram to represent a
molecule of hydrogen bromide (HBr). You need show
only the outer energy level (shell) electrons.


(1
mark) (b) The word equation for the reaction
of hydrogen with bromine is shown below. hydrogen
bromine? hydrogen bromide Write a balanced
symbol equation for this reaction. ...............
..................................................
..................................................
.....................................


(2 marks) (c) Hydrogen
bromide gas reacts with magnesium to form the
ionic compound called magnesium bromide.
Magnesium forms Mg2 ions and bromine forms Br-
ions. What is the formula for magnesium
bromide? .........................................
..................................................
..................................................
...........

(1
mark) (d) Why does magnesium bromide have a much
higher melting point than hydrogen
bromide? .........................................
..................................................
..................................................
........... ......................................
..................................................
..................................................
.............. ...................................
..................................................
..................................................
................. ................................
..................................................
..................................................
....................


(2 marks)
25
Hydrogen bromide (HBr) can be made by the
reaction of hydrogen (H2) with bromine
(Br2). (a) The diagrams represent the
outer energy levels of hydrogen and bromine
atoms. Draw a similar diagram to represent a
molecule of hydrogen bromide (HBr). You need show
only the outer energy level (shell) electrons.


(1
mark) (b) The word equation for the
reaction of hydrogen with bromine is shown
below. hydrogen bromine? hydrogen
bromide Write a balanced symbol equation for this
reaction. .H2 Br2 ? 2HBr .......................
..................................................
..................................................
...

(2
marks) (c) Hydrogen bromide gas reacts with
magnesium to form the ionic compound called
magnesium bromide. Magnesium forms Mg2 ions and
bromine forms Br- ions. What is the formula for
magnesium bromide? .....MgBr2.........If the
information is not included in the question check
the data sheet .........................


(1 mark) (d) Why does
magnesium bromide have a much higher melting
point than hydrogen bromide? Magnesium bromide is
ionic (1 mark) and a lot of energy is required
to break the strong electrostatic forces between
the ions. Hydrogen bromide forms simple covalent
molecules (1 mark) with only weak forces between
the molecules, so less energy is required to
separate them. ...................................
.........................


(2 marks)
26
Ammonia is manufactured from nitrogen and
hydrogen using the Haber process. N2(g) 3H2(g)
 2NH3(g) a) What does the symbol
mean? ............................................
..................................................
.......................... .(1 mark) b) Why is
the manufacture of ammonia carried out at high
pressure. ........................................
..................................................
............................................. ....
..................................................
..................................................
............................... ..................
..................................................
..................................................
................. ................................
..................................................
............................ (2 marks) c) Low
temperatures favour a high yield in the Haber
process. Explain whether the process is carried
out at high temperatures or low temperatures. Use
ideas about collisions between particles in your
answer. ..........................................
..................................................
..............................................
.................................................
..................................................
.......................................
.................................................
..................................................
....................................... ..........
..................................................
..................................................
......... (3 marks) d) Ammonia is reacted with
nitric acid to make ammonium nitrate. Ammonium
nitrate is Used as nitrogen source for
plants. Why do plants need nitrogen? .............
..................................................
..................................................
........................ ........................
..................................................
..................................................
....(2 marks)
27
Ammonia is manufactured from nitrogen and
hydrogen using the Haber process. N2(g) 3H2(g)
 2NH3(g) a) What does the symbol
mean? .........This means the reaction is
reversible........................................
................ .(1 mark) b) Why is the
manufacture of ammonia carried out at high
pressure. Increasing the pressure will increase
the rate of collisions so will increase the rate
of reaction. Also there are fewer molecules on
the right hand side of the equation than on the
right, increasing the pressure will force the
equilibrium to the side with the least number of
molecules, this will increase the
yield.............................................
............ .Note this is difficult because it
is asking you to apply knowledge from different
bits of the .course rates and equilibria.
This is oftent he case in questions about
ammonia.(2 marks) c) Low temperatures favour a
high yield in the Haber process. Explain whether
the process is carried out at high temperatures
or low temperatures. Use ideas about collisions
between particles in your answer. The yield may
be high at low temperatures but the rate of
reaction will very slow (1 mark this is because
the gas particles will have less energy and there
will be fewer successful collisions(1 mark) A
higher temperature is used so that ammonia can be
produced more quickly (1 mark) Note If the
question asks you to use collision theory in your
answer, use it! .(3 marks) d) Ammonia is reacted
with nitric acid to make ammonium nitrate.
Ammonium nitrate is Used as nitrogen source for
plants. Why do plants need nitrogen? .....To make
protein (1 mark) for growth (1 mark)
..................................................
..................................
.................................................
..................................................
.............................(2 marks)
28

• (a) The diagram shows a blast furnace used to
  extract iron from iron ore.
• Complete the diagram by adding the three missing
  labels.

Iron ore,____ and limestone
Blasts of hot air
Molten slag
Molten ____
29

• (a) The diagram shows a blast furnace used to
  extract iron from iron ore.
• Complete the diagram by adding the three missing
  labels.

Iron ore, coke and limestone
waste gases
Blasts of hot air
Molten slag
Molten iron
30
The table below gives information about the
atomic structure of some elements

• Fill in the blank spaces in the table
  
  (4 marks)
• b) Which element will react with element D to
  form an ionic compound?
• ..................................................
  ..................................................
  ...................................... (1 mark)
• c) Which element is monotomic?
• ..................................................
  ..................................................
  ..................................... (1 mark)
• d) Draw a diagram to show the bonding in element
  B
• 
  
  (2 marks)

31
The table below gives information about the
atomic structure of some elements

• Fill in the blank spaces in the table
  
  (4 marks)
• b) Which element will react with element D to
  form an ionic compound?
• ..................................................
  ..........B.......................................
  ..................................................
  . (1 mark)
• c) Which element is monotomic?
• ..................................................
  ............C this means that it exists as single
  atoms.........................(1 mark)
• d) Draw a diagram to show the bonding in element B

Positive metal ions
Negative electrons
Note your diagram can be simpler than this, just
show positive stationary metal ions and negative
mobile electrons