7 Energetics

HideShow resource information
  • Created by: Naana
  • Created on: 27-02-15 11:33
What is an exothermic reaction?
A reaction where heat is given out, as the reactants change to products. As a result temperature rises
1 of 11
What is an endothermic reaction?
A reaction where heat has been taken in from the surroundings, as the reactants change to products. As a result, there is a drop in temperature
2 of 11
What is enthalpy change?
When we measure heat energy taken in or given out when there is a chemical or physical change at constant pressure
3 of 11
Define standard enthalpy of formation
The enthalpy change under standard conditions, when one mole of a compound is formed from its reactants, with a reactants and products in their standard states
4 of 11
Define standard enthalpy of combustion
The enthalpy change under standard conditions, when one mole of a substance is completely burned in excess oxygen, with all reactants and products in their standard states
5 of 11
How is enthalpy change measured in a reaction?
Enthalpy change=mass of a substance x specific heat capacity x temperature change
6 of 11
What does Hess's law state?
The enthalpy change for a chemical reaction is the same, whatever route is taken from reactants to products
7 of 11
Define enthalpy of elements
The enthalpies of all elements in their standard states are taken as zero
8 of 11
What is a bond enthalpy?
The enthalpy change required to break a covalent bond with all species in the gaseous states
9 of 11
Define mean bond enthalpy
The average value of the bond enthalpy for a given type of bond given from a range of different compounds
10 of 11
Why is using mean bond enthalpies for calculations not very accurate?
Because mean bond enthalpies are averages. Calculations for specific compounds using them will only give you approximate answers
11 of 11

Other cards in this set

Card 2

Front

What is an endothermic reaction?

Back

A reaction where heat has been taken in from the surroundings, as the reactants change to products. As a result, there is a drop in temperature

Card 3

Front

What is enthalpy change?

Back

Preview of the front of card 3

Card 4

Front

Define standard enthalpy of formation

Back

Preview of the front of card 4

Card 5

Front

Define standard enthalpy of combustion

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Energetics resources »