Units

Question 1

amount of substance

Answer 1

mol

Question 2

concentration

Answer 2

mol dm–3 or g dm–3

OCR specifications do not support the use of M (molar)

Question 3

energy

Answer 3

J joules

Question 4

enthalpy

Answer 4

kJ mol–1

Question 5

mass

Answer 5

g

Question 6

rate of reaction

Answer 6

mol dm–3 s–1
These units are the standard in the context of reactions
occurring in solution, where the rate is measured in terms of the
rate at which the concentration of one of the reactants falls

Question 7

temperature

Answer 7

°C or K
Standard thermometers measure temperature in °C. In certain
practical contexts conversion to K is not required; for example in
enthalpy determinations, the measured temperature difference
is equivalent to the difference in K.

Question 8

time

Answer 8

s

Question 9

potential difference

Answer 9

V

Question 10

volume

Answer 10

cm3 or dm3
Measurements using laboratory apparatus will commonly be in
cm3
, while concentrations are expressed in terms of dm3
.
ml and l are not official SI units and their use is not supported in
OCR specifications