Calorimetry experiments for determining the enthalpy changes of reactions

2 marks · Normal

State the two steps needed to calculate the molar enthalpy change (ΔH) from calorimetry data.

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Must show: calculate Q with Q=mcΔT, divide Q by number of moles

Also accept: find energy change using mass, specific heat capacity and ΔT; calculate moles then Q/moles

Common mistakes: omitting moles step; not stating both steps

Show mark scheme and worked solution

Marking points

B1 · 1 mark · States the calculation of Q using Q=mcΔT from the data.

B2 · 1 mark · States dividing Q by number of moles of reactant for ΔH.

Worked solution

First, calculate the heat energy change (Q) using Q = mcΔT. Then divide Q by the number of moles of substance that reacted to find the molar enthalpy change (ΔH).