14.1.6

Molar Enthalpy Change

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Molar Enthalpy Change

The change in heat during a reaction carried out at a constant pressure is known as an enthalpy change. We can work out the enthalpy change per mole of substance. This is called the molar enthalpy change and the symbol for this is ΔH.

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Step 1

  • Work out the enthalpy change using the equation:
    • Heat energy transferred = mass × specific heat capacity × temperature change
    • Q = mcΔT
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Step 2

  • Calculate the number of moles using the equation:
    • moles = mass ÷ relative formula mass (Mr)
    • mol = m ÷ Mr
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Step 3

  • Divide the heat energy transferred by the number of moles.
    • Molar enthalpy change = heat energy transferred ÷ moles.
    • ΔH = Q ÷ mol

Jump to other topics

1States of Matter

2Elements, Compounds & Mixtures

3Atomic Structure

4The Periodic Table

5Chemical Formulae, Equations & Calculations

6Bonding

7Electrolysis

8Groups of the Periodic Table

9The Atmosphere

10Reactivity Series

11Metal Extraction

12Acids & Alkalis

13Chemical Tests

14Physical Chemistry

15Organic Chemistry

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