Chemistry Question Paper
9.2.5 Chemistry past paper questions
2001
Question 16 (3 marks)
Radioisotopes are used in industry, medicine and chemical analysis. For ONE of these fields, relate the use of a named radioisotope to its properties.
Medicine – Iodine
Ingested iodine concentrates in the thyroid gland and so iodine 131 can treat thyroid disorders (e.g. tumours)
Iodine 131 has a half life of just over 8 days, emits beta particles and gamma rays as it decays. This half life is long enough for it to be transported form where it is produced to where it needs to be used but it is also short enough to minimise patients exposure to radiation
It decays into non-radioactive gas, Xenon 131, which can easily escape without interfering bodily functions
Beta particles can destroy abnormal tissue. Gamma rays allow external imaging to ensure target has been reached
Question 19 (7 marks)
Name ONE type of cell, other than the dry cell or lead–acid cell, you have studied. Evaluate it in comparison with either the dry cell or lead–acid cell, in terms of chemistry and the impact on society. Include relevant chemical equations in your answer.
Dry cell – primary
Lithium Battery – secondary
Oxidation at the anode:
Zn(s) Zn2+(aq) + 2e-
Reduction at the cathode:
2MnO2 (s) + 2H+(aq) + 2e- Mn2O3 (s) + H2O (l) and NH4+ supplies H+
Oxidation at the anode:
Li(s) Li+(s) + e-
Reduction at the cathode:
I2 (s) + 2e- 2I-(s)
Lightweight and convenient to use for appliances with infrequent use e.g. torches, calculators
Needs to be disposed of
Used in cardiac pacemakers, electric watches, pocket calculators
2002
Question 19 (5 marks)
(a) Describe the conditions under which a nucleus is unstable. (2)
Nucleus can be unstable if:
Mass number is too large (atomic no. >82 = radioactive)
Proton: neutron is too low or too high
Has a large amount of energy stored can be a result of radioactive decay (b) The following is a flow diagram showing the sequence of products released during the decay of uranium. (3)
2001
Question 16 (3 marks)
Radioisotopes are used in industry, medicine and chemical analysis. For ONE of these fields, relate the use of a named radioisotope to its properties.
Medicine – Iodine
Ingested iodine concentrates in the thyroid gland and so iodine 131 can treat thyroid disorders (e.g. tumours)
Iodine 131 has a half life of just over 8 days, emits beta particles and gamma rays as it decays. This half life is long enough for it to be transported form where it is produced to where it needs to be used but it is also short enough to minimise patients exposure to radiation
It decays into non-radioactive gas, Xenon 131, which can easily escape without interfering bodily functions
Beta particles can destroy abnormal tissue. Gamma rays allow external imaging to ensure target has been reached
Question 19 (7 marks)
Name ONE type of cell, other than the dry cell or lead–acid cell, you have studied. Evaluate it in comparison with either the dry cell or lead–acid cell, in terms of chemistry and the impact on society. Include relevant chemical equations in your answer.
Dry cell – primary
Lithium Battery – secondary
Oxidation at the anode:
Zn(s) Zn2+(aq) + 2e-
Reduction at the cathode:
2MnO2 (s) + 2H+(aq) + 2e- Mn2O3 (s) + H2O (l) and NH4+ supplies H+
Oxidation at the anode:
Li(s) Li+(s) + e-
Reduction at the cathode:
I2 (s) + 2e- 2I-(s)
Lightweight and convenient to use for appliances with infrequent use e.g. torches, calculators
Needs to be disposed of
Used in cardiac pacemakers, electric watches, pocket calculators
2002
Question 19 (5 marks)
(a) Describe the conditions under which a nucleus is unstable. (2)
Nucleus can be unstable if:
Mass number is too large (atomic no. >82 = radioactive)
Proton: neutron is too low or too high
Has a large amount of energy stored can be a result of radioactive decay (b) The following is a flow diagram showing the sequence of products released during the decay of uranium. (3)