chemistry spec

Question 1

Describe how carbon dioxide helps to maintain temperatures on Earth.

Answer 1

carbon dioxide allows short
wavelength radiation to pass
through
the atmosphere to the Earth’s
surface
carbon dioxide absorbs outgoing
long wavelength radiation

Question 2

difference between condensation polymerisation

Answer 2

monomers join to form polymers but in ADDITION polymerisation ALKENES join to formpolymers

Question 3

Explain how the different dyes in X are separated by paper chromatography

Answer 3

solvent moves through paper
different dyes have different
solubilities in solvent
and different attractions for the
paper
and so are carried different
distances

Question 4

Two students tested a green compound X.
The students added water to compound X.
Compound X did not dissolve.
The students then added a solution of ethanoic acid to compound X.
A gas was produced which turned limewater milky.
Student A concluded that compound X was sodium carbonate.
Student B concluded that compound X was copper chloride.
Which student, if any, was correct?
Explain your reasoning.

Answer 4

(Student A was incorrect)
because sodium
compounds are white not
green
or
because sodium carbonate is
soluble
so can’t contain sodium ions
(Student B was incorrect)
because adding acid to
carbonate produces
carbon dioxide
so must contain carbonate not
chloride ions

Question 5

Name the two compounds used to manufacture ammonium nitrat

Answer 5

ammonia and nitric acid

Question 5

A fertiliser contains info on chemichals
Explain why this information is useful to farmers

Answer 5

shows fertilisers are
formulations
(so) farmers can choose
fertiliser with required properties
allow gives percentage /
proportion of nitrogen,
phosphorus and potassium in
the fertiliser

Question 6

Explain, in terms of particles, how and why the rate of reaction changes during the
reaction of calcium carbonate with hydrochloric acid.

Answer 6

acid particles used up
so concentration decreases
so less frequent collisions/fewer
collisions per second
so rate decreases/reaction
slows down

Question 7

Why does the mixture from the separator contain ethanol and water

Answer 7

both ethanol and water will condense, it is a reversible
reaction/equilibrium

Question 8

Compare the polymerisation reaction used to produce poly(ethene) with the
polymerisation reaction used to produce a polyester.

Answer 8

any four from:
* poly(ethene) produced
by addition
polymerisation whereas
polyester by
condensation
polymerisation
* poly(ethene) produced
from one monomer
wheareas
polyester produced from
two different monomers
* poly(ethene) produced
from ethene / alkene
whereas
polyester from a
(di)carboxylic acid and a
diol/ alcohol
* poly(ethene) is the only
product formed whereas
polyester water also
produced
* poly(ethene) repeating
unit is a hydrocarbon
whereas
polyester has an ester
linkage

Question 9

Give one reason why it is difficult to produce models for future climate change.

Answer 9

MANY different variables

Question 10

Magnesium is fixed to some steel ships.
Explain how this prevents the steel from rusting.

Answer 10

Magnesium is fixed to some steel ships.
Explain how this prevents the steel from rusting.

Question 11

Explain the process by which carbon monoxide can be produced when methane is
burned.

Answer 11

not enough oxygen
(so) incomplete combustion