Energetics Flashcards
What type of energy may be involved in a chemical reaction?
Light
Electrical
Heat
Sound
What is thermochemistry the study of?
Heat changes during chemical reactions.
What happens to chemical bonds during a reaction?
They break and new ones are formed.
Why do most chemical reactions involve an energy change?
Energy is required to break bonds and is given out when new bonds are formed.
Why is it important to be able to measure the amount of energy involved in a chemical reaction?
- You can measure the energy values of fuels
- You can calculate the energy requirements for industrial processes
- You can theorise an amount of energy required/released when breaking/making bonds
- It helps predict whether the reaction will take place
What is specific heat capacity?
The amount of heat need to raise the temperature of a substance by 1K.
What units is specific heat capacity measured in?
Joules per gram per kelvin.
Jg-1K-1
Is neutralising an acid an exothermic or endothermic reaction?
Exothermic
What units are used to measure the energy involved in a chemical reaction?
KJmol-1
What is a bond enthalpy?
This is the standard enthalpy change associated with breaking one mole of bonds in a gaseous substance into individual gaseous atoms.
What is bond dissociation enthalpy?
Enthalpy change required to break a covalent bond with all species in a gaseous state.
Give the definition of ‘mean bond enthalpy’.
the average enthalpy change that takes place when breaking 1 mole of a given bond in the molecule of a gaseous species under standard conditions
What is an enthalpy change?
A measure of heat energy given out or taken in when a chemical or physical change occurs at constant pressure.
