Chemistry Reference
In-Depth Information
(iv)
Describe how you can measure this pH
change.
[1]
burette
(v)
The equation for the reaction is
KOH + HNO
3
→ KNO
3
+ H
2
O
hydrochloric
acid
State the name of the salt formed in this
reaction. [1]
[Total: 12]
(Cambridge IGCSE Chemistry 0620 Paper 02 Q1
November 2009)
28
A solution of calcium hydroxide in water is
alkaline.
a
Which
one
of the pH values below is alkaline?
Put a ring around the correct answer.
pH 3 pH 6 pH 7 pH 11
[1]
b
Which of the following is the common name
for calcium hydroxide?
Tick
one
box.
flask
solution of
calcium hydroxide
cement
Describe how you would carry out this
titration. [3]
[Total: 10]
(Cambridge IGCSE Chemistry 0620 Paper 21
Q5 November 2010)
limestone
quicklime
slaked lime
29
Ammonia is an important industrial chemical.
a (i)
Give the electron structure of an atom of
nitrogen. [1]
(ii)
Use this electronic structure, rather than
the valency of nitrogen, to explain why the
formula of ammonia is NH
3
not NH
4
. [2]
b
Ammonia is made by the Haber Process.
N
2
(
g
) + 3H
2
(
g
)
[1]
c
Some farmers use calcium hydroxide to control
soil acidity.
(ii)
Why is it important to control soil
acidity? [1]
(ii)
Acid rain can cause soil to become acidic.
Describe how acid rain is formed. [3]
d
Calcium hydroxide reacts with hydrochloric acid.
calcium hydroxide + hydrochloric acid →
calcium chloride + water
(ii)
State the name of this type of chemical
reaction. [1]
(ii)
A dilute solution of calcium hydroxide can
be titrated with hydrochloric acid using the
apparatus shown.
2NH
3
(
g
)
forward reaction is exothermic
L
The percentage of ammonia in the equilibrium
mixture varies with conditions.
Pressure/atmospheres
100
200
300
400
% ammonia at 300 °C
45
65
72
78
% ammonia at 500 °C
9
18
25
31
The conditions actually used are
200 atmospheres, 450 °C and an iron catalyst.
(ii)
The original catalyst was platinum. Suggest
a reason why it was changed to iron.
[1]
(ii)
Explain why the highest pressure gives
the highest percentage of ammonia in the
equilibrium mixture.
[2]
