Lesson 8.1.2

8.1.2 Measuring enthalpy changes Quiz: Pearson Edexcel Chemistry, Unit 8

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 8.1.2, Measuring enthalpy changes: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 8: Energetics I, written with Revision Ninja.

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The 20 questions

  1. What is the expression used to calculate the energy transferred to a known mass of water in an enthalpy experiment?

    • q = m x c x delta T
    • q = c x delta T / m
    • q = m / c x delta T
    • q = m x c / delta T

  2. What is the specific heat capacity of water usually taken to be in calorimetry calculations?

    • 41.8 J g-1 K-1
    • 0.418 J g-1 K-1
    • 2.10 J g-1 K-1
    • 4.18 J g-1 K-1

  3. 50.0 g of water is heated by 12.0 K in an experiment. How much energy is transferred to the water, using c = 4.18 J g-1 K-1?

    • 0.502 kJ
    • 25.1 kJ
    • 2.51 kJ
    • 2508 kJ

  4. In a spirit burner experiment, 2.00 g of ethanol (Mr = 46.0) heats 100 g of water by 10.0 K. What is the enthalpy of combustion of ethanol, in kJ mol-1?

    • -191 kJ mol-1
    • -9.61 kJ mol-1
    • -96.1 kJ mol-1
    • -4.18 kJ mol-1

  5. Why is the experimental enthalpy of combustion of an alcohol in a spirit burner usually less exothermic than the data book value?

    • The water absorbs more heat than the fuel releases, which means that the measurement is too large
    • Alcohols never burn completely in air, so no heat is released in a spirit burner at all
    • The data book values are measured at 100 K, which is a very different temperature from the lab
    • Heat is lost to the surroundings and the apparatus, so less heat reaches the water

  6. In a neutralisation experiment, 25.0 cm3 of 1.00 mol dm-3 HCl is mixed with 25.0 cm3 of 1.00 mol dm-3 NaOH. The temperature rises by 6.0 K. What is the enthalpy of neutralisation? Assume the solution has mass 50.0 g and c = 4.18 J g-1 K-1.

    • -100 kJ mol-1
    • -50.2 kJ mol-1
    • -1.25 kJ mol-1
    • +50.2 kJ mol-1

  7. Which statement about recording enthalpy values from experiments is correct?

    • Units are optional if the value is quoted in joules
    • Both the sign and the units must be given in the final answer
    • The sign is always positive in experimental results
    • Only the magnitude is needed, since the sign is understood

  8. Which change most reduces the percentage error in a calorimetry experiment of this type?

    • Using a smaller mass of water so that less heat is absorbed by the water and the change is more visible
    • Using a thinner container so that heat escapes more easily and the temperature rise is reduced
    • Using a larger temperature change so that the measurement uncertainty is a smaller fraction
    • Recording the temperature less often so that fewer readings are needed during the experiment

  9. A student uses a polystyrene cup with no lid. Which effect is most likely to occur?

    • Heat is lost to the surroundings, so the measured temperature rise is too small
    • The measured temperature rise is too large because heat enters the cup
    • The enthalpy change becomes exactly zero
    • The mass of water increases during the experiment

  10. Which method is used when an enthalpy change cannot be measured directly?

    • Hess's Law or an indirect calculation using other measured enthalpy changes
    • Measuring the colour change of an indicator added to the reaction mixture during the experiment
    • Using a pH meter to read the heat released directly from the solution at each stage
    • Counting the bubbles produced by the reaction and converting the count into an energy value

  11. In an experiment, the temperature falls by 4.0 K when a dissolving salt is added to 100 g of water. What is the sign of the enthalpy change?

    • Zero, because the temperature change is small
    • Negative, because heat is released to the water
    • Positive, because heat is absorbed from the water
    • Negative, because the mass of water fell

  12. A student dissolves 2.00 g of solid in 50.0 cm3 of water and the temperature falls by 2.0 K. Which assumption is needed to calculate the enthalpy change?

    • The density of water is 1.00 g cm-3, so 50.0 cm3 has a mass of 50.0 g
    • The solid has no mass, so the mass of the solution is taken to be the mass of the water alone
    • The reaction releases exactly 2.0 J of heat to the solution, which is the value used in the calculation
    • The water evaporates completely during the experiment so that no heat is retained in the solution

  13. Why is an insulated container used in a calorimetry experiment?

    • To make the reaction endothermic so that the temperature of the solution rises during mixing
    • To reduce heat loss so that more of the energy change is transferred to the water
    • To increase the speed of the reaction by holding the reagents at a constant high temperature
    • To keep the reagents in the solid state so that they can be weighed accurately before the reaction

  14. What is the sign and value of the enthalpy change if 0.0100 mol of a substance releases 0.5 kJ of heat?

    • -50 kJ mol-1
    • +0.5 kJ mol-1
    • +50 kJ mol-1
    • -5.0 kJ mol-1

  15. A reaction releases 1.26 kJ of heat when 0.0250 mol of a reagent reacts. What is the enthalpy change in kJ mol-1?

    • +50.4 kJ mol-1
    • -1.26 kJ mol-1
    • -31.5 kJ mol-1
    • -50.4 kJ mol-1

  16. What does the term 'specific heat capacity' describe?

    • The mass of substance needed to absorb 1 J of energy when its temperature rises by one kelvin
    • The energy needed to raise the temperature of 1 g of a substance by 1 K
    • The energy needed to melt 1 mol of a substance at its melting point under standard pressure
    • The energy released when 1 mol of a substance burns completely in excess oxygen at 298 K

  17. In a calorimetry experiment, which quantity must be known to convert a measured energy change into an enthalpy change in kJ mol-1?

    • The colour of the solution at the end of the reaction, which indicates how much heat was released
    • The number of protons in the reagent molecule, which determines the energy of each bond
    • The pH of the water before the reaction, which sets the starting energy of the solution
    • The amount in moles of the limiting reactant or fuel

  18. A graph of temperature against time is extrapolated in a displacement reaction. What is the purpose of this extrapolation?

    • To estimate the temperature change that would have occurred without heat loss during the reaction
    • To calculate the pH of the final solution from the temperature readings taken at each point
    • To determine the molar mass of the metal by measuring the mass lost during the displacement reaction
    • To find the rate constant of the reaction from the gradient of the extrapolated line on the graph

  19. Which of the following is a valid source of uncertainty in an enthalpy experiment?

    • The number of significant figures in the specific heat capacity constant only
    • The colour of the calorimeter
    • The atomic mass of hydrogen in the water
    • The thermometer reading, which is limited to about 0.5 K

  20. Which statement about the energy transfer in a calorimetry experiment is correct?

    • The energy transferred equals the mass of the reactant multiplied by its molar mass, giving the heat released
    • The energy transferred to the water equals m c delta T, assuming the water absorbs all the heat from the reaction
    • The energy transferred is always equal to the molar volume of the gas produced in the reaction
    • The energy transferred equals delta T divided by the specific heat capacity of the solution used

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