g2 exam Flashcards
(i)11/137.3
(ii) 19.2
(iii) 8.0 × 10–3
(iv) any pH > 7 but <15
A student repeated the experiment in (b) using a 0.11 g sample of barium that
had blackened following exposure to the air.
Suggest why the volume of hydrogen produced would be slightly less than the
volume collected using pure barium.
Less barium to react OR
some barium has already reacted
Describe and explain the trend, down the group, in the reactivity of the Group 2
elements with water. (5)
When heated strongly, CaCO3 decomposes.
Write an equation, including state symbols, for the thermal decomposition of CaCO3. (2)
The student had added the exact amount of calcium required to react with the
hydrochloric acid used. After carrying out the experiment, the student accidentally
added some more calcium. The student was surprised that the extra calcium still
reacted.
Explain this observation. Include an equation in your answer.
Old samples of magnesium oxide become contaminated with magnesium carbonate.
(i) Suggest how this contamination takes place.
MgO has reacted with CO2
Explain, with the aid of equations, why the resulting solution contained only one
dissolved compound of magnesium.
Explain why the student obtained different volumes of gas by reacting water with
the same mass of calcium and strontium. (2)
different numbers of moles/atoms/ different Ar
values
so different number of moles of H2/more moles of Ca
Explain why the first and second ionisation energies of strontium are less than
those of calcium.
Carbon dioxide can be prepared easily in the laboratory by the action of heat on most
carbonates. Construct an equation to illustrate this reaction.
CaCO3 → CaO + CO2
state symbols not required
Chewing chalk has been used for many years to combat excess stomach acid and
indigestion tablets often contain calcium carbonate, CaCO3. Suggest, with the aid of an
equation, how these tablets work. (2)
When barium metal is added to water, the reaction taking place is much more vigorous
than with calcium.
Explain why barium is more reactive than calcium.
- barium atoms are larger
- barium atoms have more shielding
- this outweighs the increase in nuclear charge
- barium electrons are lost more easily
/less energy required
/ionisation energy decreases
Suggest how strontium carbonate is converted into strontium oxide.
heat
Suggest how the company could minimise the environmental impact of strontium
production from the ore.
98% waste produced which must be disposing of /made
into something worthwhile/CO2
being removed by
something sensible/ 1
any sensible comment
