3a+b- Physical Chemistry❗️ Flashcards
Describe in terms of energy an exothermic reaction
When more energy is released when making bonds, than was taken in
Describe in terms of energy an endothermic reaction
When more energy is taken in when making bonds, than was released out
What is the formula for calculating energy change?
Mass x 4.2 x temp change
What is the formula for calculating mol?
Mol = volume x concentration
What are the steps to calculating PER MOLE energy change (calorimetry)
1) calculate energy change (KJ)
2) find moles (MOL)
3) divide energy change by moles (KJ/MOL)
Energy released =
- (exothermic)
Energy absorbed =
+ (endothermic)
What are examples of exothermic reactions?
- combustion
- neutralisation
- oxidation
What are examples of endothermic reactions?
- Thermal decomposition
What are the factors affecting rate of reaction?
1) Concentration
2) temperature
3) surface area
How does temperature effect rate of reaction?
- particles have more energy and are moving faster
- more FREQUENT collisions
How does higher concentration effect rate of reaction?
- more particles in a volume
- particles have more energy
- more frequent collisions
How does surface area effect rate of reaction?
larger surface area —> more frequent collisions
What is activation energy?
The minimum energy needed for reactant particles to form products when they collide
How do catalysts speed up a reaction?
They lower the reactions activation energy by offering an alternative reaction pathway
