C1 2022

Question 1

Give two features of a reaction in a dynamic equilibrium

Answer 1

The forward and reverse reaction proceed at equal rates
Concentrations remain constant

Question 2

A gas phase reaction is at equilibrium. When the pressure is increased the yield of product decreases

Answer 2

More moles to the right of the reaction

Question 3

State how the relative abundance of 185Re+ is determined in a TOF mass spectrometer

Answer 3

The abundance is proportional to the current produced
At the detector plate, the ions gain an electron

Question 4

Define the term mean bond enthalpy

Answer 4

Enthalpy change to break 1mol bonds averaged over a range of compounds

Question 5

State how a buffer solution can be made from solutions of KOH and ethanoic acid
State how this buffer solution resists change in pH when a small amount of acid is added

Answer 5

Excess ethanoic acid is added to KOH
CH3COO0- reacts with H+

Question 6

identify a reagent or test tube that could be used to distinguish between aquatic solutions of SO2 and SO3 with the same concentrations

Answer 6

pH meter
SO2 - 2-3
SO3 - 0-1

Question 7

The mass spectrum of the element phosphorus has a peak at m/z = 124
Give the formula of the species responsible for this peak

Answer 7

31P4+

Question 8

Give an ionic equation for the formation of this gas rom the impurity

Answer 8

2H+ + CO32- -> Co2 + H2O

Question 9

Magnesium is used in the extraction of titanium from titanium chloride
Give an equation for this reaction

Answer 9

TiCl4 + 2Mg -> 2MgCl2 + Ti

Question 10

Give half equations for alkaline hydrogen oxygen fuel cells

Answer 10

O2 + 2H2O + 4e- -> 4OH-
2H2O + 2e- -> 2OH- + H2