Enthalpy changes are measured on a set of standard conditions as the enthalpy changes can vary with temperature, pressure or concentration. These are called standard enthalpy changes ΔHθStandard pressure is 100kPa (1 atmosphere of pressure is 101kPa)Standard temperature is 298KStandard concentration is 1 moldm-3The standard state of a substance is the physical state of a substance (solid, liquid or gas) under standard conditions.
Standard Enthalpy Changes and Standard Conditions
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Specification: OCR Chemistry A (H032), AS-level, 3.2.1 Enthalpy changes. Topic: Enthalpy.
Key terms in this lesson
- Enthalpy
- A measure of the total energy of a chemical system.
More in Enthalpy
- Enthalpy and Enthalpy Changes
- Endothermic and Exothermic Reactions
- Activation Energy
- Enthalpy Change of Reaction
- Enthalpy Change of Formation
- Enthalpy Change of Combustion
- Enthalpy Change of Neutralisation
- Measuring the Enthalpy Change of Combustion
All 19 lessons in Enthalpy · All OCR AS-level Chemistry topics