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 Form 4 Chemistry: Energy changes in chemical and physical processes lessons

Introduction: meaning of specific heat capacity,heat content and types of heat changes in chemical reactions

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Answer Text:
- Most chemical and physical process are accompanied by energy changes which occur in the form of heat measured in joules (J) and kilojoules (KJ).
- The heat results from the motion of atoms and molecules.
Specific heat capacity
- Specific heat capacity of a substance is the number of joules required to raise the temperature of one gram of the substance by one degree Kelvin e.g. – SHC for water is #4.18Jg^-1K^-1 #
The heat content
(Enthalpy) of a system.
- Heat content is denoted by H; while heat change is denoted as ΔH1;
- And; ΔH = HProducts -HReactants = H2-H1
- Heat changes in chemical reactions can either be exothermic and endothermic.