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Date May 2018 Marks available 1 Reference code 18M.3.sl.TZ1.9
Level SL Paper 3 Time zone TZ1
Command term Outline Question number 9 Adapted from N/A

Question

Greenhouse gases absorb infrared radiation.

Identify one naturally occurring greenhouse gas, other than carbon dioxide or water vapour, and its natural source.

[2]
a.

Formulate an equation that shows how aqueous carbon dioxide produces hydrogen ions, H+(aq).

[1]
b.

The concentrations of oxygen and nitrogen in the atmosphere are much greater than those of greenhouse gases. Outline why these gases do not absorb infrared radiation.

[1]
c.

Markscheme

M18/4/CHEMI/SP3/ENG/TZ1/09.a/M

 

Accept “nitrous oxide”.

Accept “electrical discharges/lightning”.

[2 marks]

a.

CO2(aq) + H2O(l)  H+(aq) + HCO3(aq)

OR

CO2(aq) + H2O(l) H2CO3(aq) AND H2CO3(aq) H+(aq) + HCO3(aq)

 

Accept CO2(aq) + H2O(l) 2H+(aq) CO32–(aq).

Accept equations with single arrow.

[1 mark]

b.

no change in polarity/dipole «moment when molecule vibrates»

 

Do not accept “non-polar” or “no dipole moment” – idea of change must be there.

[1 mark]

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Options » C: Energy » C.5 Environmental impact—global warming
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Options » C: Energy
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