CHEMISTRY ROUND UP TASK
(d) Using your answers to (b) and (c) calculate the mass of oxygen that combines with the
copper.
g
m
(e) Using your answers to (b) and (d) calculate the formula of copper oxide. Show your
working.
[ Af : O, 16; Cu, 64]
[2]
[Total: 6]
3
A student does two experiments both involving a reaction between two compounds.
In each case the apparatus and contents are weighed at the start of the reaction and again
after the reaction has finished.
(a) Powdered calcium carbonate is added to an excess of hydrochloric acid in a conical
flask.
(i) Describe what is observed in the flask as the reaction progresses.
[1 ]
(ii) Construct the equation for the reaction.
[1 ]
(iii) Will the total mass of the flask and contents increase, decrease or remain the same
after the reaction has finished?
Explain your answer.
[1 ]
(b) Dilute sulfuric acid is added to aqueous barium chloride in a beaker.
(i) Describe what is observed in the beaker.
[1 ]
(ii) Construct the equation for the reaction.
[1 ]
(iii) Will the total mass of the beaker and contents increase, decrease or remain the
same after the reaction has finished?
Explain your answer.
[1 ]
[Total: 6]
4
The diagram below shows the results of an experiment to identify the components of mixtures
X and Y . Each mixture is known to contain one or more of the single substances L, M , N and
P and no other substance.
B
e
e
e
o
o
e
rL
rM
N
P
X
Y
single !substances
mixtures
start iline
(a) What name is given to this experiment?
[1 ]
(b) Draw a line on the diagram to show the solvent level at the beginning of the experiment.
[1 ]
(c) What piece of apparatus does the student use to place spots of L , M , N , P, X and Y on
the start line?
[1 ]
(d) In this experiment the substances L , M, N and P are not coloured.
What name is given to a substance which will change L, M , N and P into coloured
spots?
[1 ]
(e) Use the diagram to deduce which of the substances L, M . N and P are present in
(i) mixture X ,
(ii) mixture Y .
(f)
[2]
Line B shows the solvent front at the end of the experiment.
Using a ruler to measure the distances travelled by substance P and the solvent front,
calculate the Rf value of P.
,
ft value of P =
[2]
[Total: 8]
5
(a ) The table shows the properties of some metals.
metal
density
in g / cm3
melting point
in °C
relative
strength
relative
electrical
conductivity
cost
aluminium
2.7
660
7.0
4.0
expensive
iron
7.9
1535
21.0
1.1
cheap
lead
11.3
328
1.5
0.5
expensive
silver
10.5
962
2.0
6.7
very expensive
tungsten
19.4
3420
12.0
2.0
expensive
Use the information in the table to answer the questions.
Which metal would be most useful for making overhead power cables?
Give two reasons for your answer.
(i)
metal
reason 1
reason 2
[2 ]
Why is iron and not tungsten used to reinforce concrete?
(ii)
[1 ]
(iii)
The front part of a space rocket is called a nose cone. The nose cone gets very hot as the
space rocket moves through the air.
Which metal is best to make a space rocket nose cone? Explain your answer.
[1]
( b ) Tungsten is a transition element.
State two physical properties of transition elements which are not shown by Group I elements.
1
2
[2]
( c) When extremely hot tungsten reacts with oxygen, tungsten( VI) oxide is formed.
Balance the chemical equation for this reaction.
.W +
,
02
-> 2W 03
[ 2]
( d) Some information about the reaction of four metals with oxygen is given.
cobalt:
reacts slowly at high temperatures
iron:
thin wire burns when heated strongly
magnesium: burns when heated
tungsten:
reacts very slowly at extremely high temperatures
List these metals in order of their reactivity. Put the least reactive metal first.
least reactive
most reactive
[2 ]
( e ) The table compares the time taken for reaction of an alloy with ethanoic acid, nitric acid and
phosphoric acid, each at three different concentrations. The time taken for the alloy to decrease
in mass by 1.0 g was measured. All other conditions were kept the same.
time taken for reaction / hours
acid
concentration of acid concentration of acid concentration of acid
0.04 mol / dm3
0.02 mol / dm3
0.01 mol / dm3
ethanoic acid
92
190
410
nitric acid
2
6
18
19
39
80
phosphoric acid
(i)
How does the concentration of acid affect the rate of reaction?
[1]
( ii)
Which acid reacts most rapidly with the alloy?
[1]
(iii)
Predict how long it would take for the alloy to decrease in mass by 1.0 g using phosphoric
acid of concentration 0.03 mol / dm3.
time taken =
(iv )
hours [1]
Suggest which one of these pH values is the pH of concentrated aqueous ethanoic acid.
Draw a circle around the correct answer.
pH 4
pH 7
pH 10
pH 13
[1]
[Total: 14]
6
The electrical conductivity of a substance is related to its structure and bonding.
(a) Graphite and diamond are both forms of solid carbon. Explain why graphite conducts
electricity but diamond does not.
[2]
(b) Explain why solid sodium chloride does not conduct electricity whereas aqueous sodium
chloride does conduct electricity.
[2]
(c) Complete the following table about electrolysis using inert graphite electrodes.
electrolyte
product at cathode
product at anode
molten lead(ll)
bromide
aqueous copper(II)
sulfate
copper
dilute sulfuric acid
oxygen
[3]
(d) Describe one commercial use of electrolysis.
use
electrolyte used
ionic equation for reaction at the cathode
[3]
[Total: 10]
7 Ethanol, C2H5OH, can be manufactured by two different processes.
•
•
process 1 - the catalysed addition of steam to ethene
process 2 - the fermentation of glucose
(a) Name the type of reaction used to manufacture ethene.
[1]
(b) (i) Write the equation for process 1.
[1]
(ii) Suggest the name of the alcohol made when the alkene C3H6 reacts with steam in
the presence of a catalyst.
[ 1]
(c) The equation for process 2 is shown below.
C6H1206(aq)
-» 2C H OH(aq) + 2C02(g)
2 5
(i) Describe two essential conditions required for efficient fermentation.
[2]