Energy changes

Question 1

What is a exothermic reaction, and how does it change the temperature?

Answer 1

A reaction which transfers energy to the surroundings, usually by heating. It is shown by a rise in temperature.

Question 2

What is a endothermic reaction, and how does it change the temperature?

Answer 2

A reaction which takes in energy from the surroundings. This is shown by a fall in temperature.

Question 3

What must always be supplied to break bonds?

Answer 3

Energy

Question 4

Is bond breaking endothermic or exothermic?

Answer 4

Endothermic

Question 5

Is bond forming endothermic or exothermic?

Answer 5

Exothermic

Question 6

What is a electrochemical cell?

Answer 6

A basic system made up of 2 different electrodes in contact with an electrode

Question 7

What is a fuel cell?

Answer 7

An electrical cell that’s supplied with a fuel and oxygen and uses energy from the reaction between them to produce electrical energy efficiency

Question 8

What happens when the fuel enters the cell?

Answer 8

It becomes oxidised and sets up a potential difference with in the cell

Question 9

Explain a redox reaction:

• What happens at each electrode?
• What does the overall reaction release?

Answer 9

In hydrogen-oxygen fuel cells, different things happen at each electrode - oxidation at the anode and reduction at the cathode. The overall reaction releases electrical energy without a load of pollution