Heat energy changes Flashcards
how can you measure temperatures change
put a polystyrene cup in a large beaker of cotton wool for insulation
add reagent of fixed amounts
measure temperature
add fixed amount of second reagent and mix
put lid and record min and max temp and temp change
how does change in temperature depend on type of reagent used
- dissolving salts: exo/exo
- neutralisation: exo except ethanoic and sodium
- displacement: exo
- precipitation: exo
what is an exothermic reaction
when energy is released to form bonds, energy released is greater than used to break
what is an endothermic reaction
when the energy used to break the bonds is greater than the energy released
energy is supplied to bonds
what is the formula for energy change
energy required - energy released
if positive = endo
if negative - exo
what is activation energy
the minimum energy the colliding particles need in order to react and bonds break
The activation energy can be lowered by the addition of a catalyst
