Inquiry question: What energy changes occur in chemical reactions?
conduct practical investigations to measure temperature changes in examples of endothermic and exothermic reactions, including:
combustion
dissociation of ionic substances in aqueous solution
investigate enthalpy changes in reactions using calorimetry and (heat capacity formula) to calculate, analyse and compare experimental results with reliable secondary-sourced data, and to explain any differences
construct energy profile diagrams to represent and analyse the enthalpy changes and activation energy associated with a chemical reaction
model and analyse the role of catalysts in reactions
Enthalpy and Hess’s Law
Inquiry question:How much energy does it take to break bonds, and how much is released when bonds are formed?
explain the enthalpy changes in a reaction in terms of breaking and reforming bonds, and relate this to:
the law of conservation of energy
investigate Hess’s Law in quantifying the enthalpy change for a stepped reaction using standard enthalpy change data and bond energy data, for example:
carbon reacting with oxygen to form carbon dioxide via carbon monoxide
apply Hess’s Law to simple energy cycles and solve problems to quantify enthalpy changes within reactions, including but not limited to:
heat of combustion
enthalpy changes involved in photosynthesis
enthalpy changes involved in respiration
Entropy and Gibbs Free Energy
Inquiry question: How can enthalpy and entropy be used to explain reaction spontaneity?
analyse the differences between entropy and enthalpy
use modelling to illustrate entropy changes in reactions
predict entropy changes from balanced chemical reactions to classify as increasing or decreasing entropy
solve problems using standard references and (Gibbs free energy formula) to classify reactions as spontaneous or nonspontaneous
predict the effect of temperature changes on spontaneity (ACSCH070)