2016 Chemical, Energy and Resources Jun

Question 1

At rtp, the first four members of the alkanes are all gases but the first four alcohols are liquid. Explain in terms of intermolecular forces

Answer 1

• Alcohols have hydrogen bonds (and induced dipole)

* Hydrogen bonds are stronger than induced dipoles (in alkanes)

Question 2

Using le Chateliers principle predict the effect on equilibrium.

The gas mixture is compressed

Answer 2

• Equilibrium (position) shifts to right

AND turns paler (brown)•

Question 3

Using le Chateliers principle predict the effect on equilibrium.

Placed in a warm water bath

Answer 3

• Equilibrium (position) shifts to left
AND turns darker/deeper (brown
• (Forward) reaction is exothermic

Question 4

State two ways in which catalysts help make processes more sustainable

Answer 4

• Lower temperatures/lower pressures (can be used

* (Catalysts are often enzymes) generating specific products

Question 5

Two sources of nitrogen oxides in the stratosphere

Answer 5

• Thunderstorms/lightning AND aircraft 

Question 6

Show how nitrogen monoxide catalyses the breakdown of ozone

Answer 6

• NO + O3 -> NO2 + O2

* NO2 + O -> NO + O2

Question 7

The greenhouse effect of a gas in the atmosphere is dependent on two factors

Answer 7

• Abundance (in atmosphere)
• Ability to absorb infrared/IR (radiation
• Residence time