2021 P1 Q11 - Calculate Enthalpy Change of Neutralisation
Let's take a look at 2021 A Levels H2 Chemistry Paper 1 Question 11.
We are required to calculate the enthalpy change of neutralisation for the mentioned experiment.
Using a diagram is useful to help us visualise the process.
We can use the following steps to calculate enthalpy change for calorimetry questions.
1. Determine heat released by neutralisation
Heat absorbed by water is given by mass of water x specific heat capacity of water x change in temperature of water.
heat absorbed by solution = mw.c.ΔT
We can calculate heat absorbed to be 4.18 kJ.
Assuming no heat loss to surrounding, heat released by reaction will be the same value 4.18 kJ.
2. Determine limiting reagent
We can calculate moles of reactants H2SO4 and NaOH to be 0.1 mol.
Hence NaOH is limiting.
Since enthalpy change of neutralisation is with respect to per mole of water, we need to calculate moles of water formed from the limiting reagent.
Hence moles of water formed = moles of NaOH = 0.1 mol
3. Calculate enthalpy change of neutralisation
Enthalpy change is - q / moles of water which works out to be -41.8 kJ mol-1.
Note we put a negative sign for enthalpy change of neutralisation since the reaction is exothermic.
Finally we can compare the options to determine the answer to this question is option C.
Topic: Energetics, Physical Chemistry, A Level Chemistry, Singapore
Back to list of questions for 2021 A Level H2 Chemistry Paper 1.
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