5 x 1 hour lessons

This module introduces the key concepts of enthalpy changes and how they are measured and interpreted. You’ll learn to define and use standard enthalpy changes of reaction, formation, combustion, and neutralisation, and understand the conventions used when assigning positive and negative values.

You’ll also learn how to use calorimetry to determine enthalpy changes experimentally, and how to identify possible sources of error in practical enthalpy work. The module ends with Hess’s Law and how to use energy cycles and enthalpy data to calculate unknown values — a frequent exam skill.

By the end of this module, you'll be able to:

• Define and use terms such as standard enthalpy of reaction, formation, combustion, and neutralisation

• Understand and use the conventions for positive and negative enthalpy changes

• Carry out calculations using q = mcΔT for enthalpy change from experimental data

• Construct and use Hess’s Law cycles to determine enthalpy changes

• Use bond enthalpy data to estimate overall enthalpy change in reactions

OCR (A) specification points covered: 3.2.1 Enthalpy changes