AQA Energy Change and Cells

State the law of conservation of energy.

• All energy is equal
• Energy cannot be created or destroyed, only transferred.
• Energy lost to surroundings
• Energy is equal to input and some output

How does the law of conservation of energy apply to chemistry?

• Energy is transferred to/from surroundings.
• Energy is lost to chemicals
• Reactants absorb energy from products
• Mass is lost

What is an exothermic reaction?

• Energy taken in from surroundings
• Energy lost to chemicals
• Energy lost to surroundings
• Energy gained from electricity

Give an example of an exothermic reaction

• Melting
• Combustion
• Freezing
• Photosynthesis

What happens to the temperature of the surroundings during an exothermic reaction?

• Decrease
• Constant
• Stays the same
• Increase

What is an endothermic reaction?

• Energy taken in from surroundings
• Energy lost to surroundings
• Energy lost to chemicals
• Energy gained from electricity

Give an example of an endothermic reaction.

• Explosion!
• Thermal decompostion
• Freezing
• Neutralisation

What happens to the temperature of the surroundings during an endothermic reaction?

• Increase
• Stays the same
• Decrease
• Constant

State a use of exothermic reactions

• Cooling drinks
• Drying agent
• Hand-warmers
• Oxidising agent

State a use of endothermic reactions

• Oxidising agent
• Drinks heater
• Sports cool packs.
• Catalyst