Part 8 Chemical Reaction and Energy Flashcards
State the law of conservation of energy.
Energy can neither be created nor destroyed, but it can be changed from one form to another form.
According to definition, under which condition could the “heat change” regarded as the “enthalpy change” ?
Heat change at constant pressure
What is meant by the term “standard enthalpy change” ?
The enthalpy change when the number of moles of reactants represented by the thermochemical equation react completely under standard condition.
State the standard condition for standard enthalpy change of a reaction.
25 ˚C , 1atm / 298K ,1atm
What is meant by the term “standard enthalpy change of combustion” ?
Standard enthalpy change of combustion of a substance is the enthalpy change when one mole of it is completely burnt in oxygen under standard condition.
What is meant by the term “standard enthalpy change of neutralisation” ?
The enthalpy change when one mole of water is formed from neutralisation between an acid and an alkali under standard condition.
What is meant by the term “catalyst” ?
Catalyst is a substance which can change the rate of reaction but itself remains chemically unchanged after the reaction.
What is meant by the term “standard enthalpy change of formation” ?
The enthalpy change when one mole of product is formed from its constituent elements in their standard state under standard condition
State “Hess’s law”.
Total enthalpy change of a chemical reaction is independent of the pathway between initial and final states.
