Enthalpy

Cards (13)

Tell me about a exothermic reaction
- heat is given out
- temperature increases
- delta h is negative
tell me about an endothermic reaction
- heat is taken in
- the temperature decreases
- delta h is positive
draw an exothermic diagram * image will load
image shown below
draw an endothermic diagram * image will load
image shown below
what are the standard conditions to find the enthalpy change
- 100 kpa
- 298 k
- 1 moldm3
what is the standard enthalpy change of formation
when one mole of a compound is formed from its elements under standard conditions
what is enthalpy change of combustion
When one mole of an element or compound reacts completely with oxygen under standard conditions
what is enthalpy change of neutralisation
when one mole of water is formed from the reaction of an acid with a base under standard conditions
Why may values be different in a lab
- heat loss to apparatus and surroundings
- not carried out under standard conditions
- incomplete combustion
how do you work out the average bond enthalpy
bonds broken + bonds formed
draw a Hess cycle for combustion
reactants ——> products

oxides
* arrows go down
draw a Hess cycle for formation
reactants ——> products
elements
* arrows go up
for Hess cycle what is the formula
reactants + products