What is chemical energy?
A form of potential energy that lies within chemical bonds.
What are chemical bonds?
The forces of attraction that bind atoms together in compounds.
What is enthalpy (H)?
The heat content that is stored in a chemical system.
Describe the law of conservation of energy.
The amount of energy that leaves a chemical system is exactly the same as the amount that goes to the surroundings.
- heat loss = heat gain (temp. Inc.)
- heat gain = heat loss (temp. Dec.)
What is enthalpy change?
The heat exchange with the surroundings during a chemical reaction, at constant pressure.
Enthalpy (products) - enthalpy (reactants).
What makes a reaction exothermic?
- Enthalpy (products) < Enthalpy (reactants)
- heat loss to the surroundings
- enthalpy change is negative
- temp of surroundings increases
What makes a reaction endothermic?
- Enthalpy (products) > enthalpy (reactants)
- heat gain from the surroundings
- enthalpy change is positive
- temp of surroundings decreases
Name 2 exothermic reactions.
- Oxidation of fuels
- Respiration
Name 2 endothermic reactions.
- Thermal decomposition
- Photosynthesis
