Chemistry: Energy Changes

Question 1

what is an exothermic reaction

Answer 1

transfer of energy from an object to its surroundings

Question 2

what is an endothermic reaction

Answer 2

transfer of energy from surroundings to an object

Question 3

how can you measure the amount of energy released by a chemical reaction

Answer 3

taking the temperature of the reagents then mixing them in a polystyrene cup and measuring the temperature of the solution at the end of the reaction

Question 4

what do reaction profiles do

Answer 4

show the relative energies of the reactants and products in a reaction

Question 5

what happens to break bonds

Answer 5

energy is supplied

Question 6

what happens when bonds form

Answer 6

energy is released

Question 7

what is an electrochemical cell

Answer 7

basic system made of two different electrodes in contact with electrolysis

Question 8

what three factors affect the voltage of a cell

Answer 8

the material/metal used
the difference in reactivity
the electrolyte used

Question 9

what do fuel cells use to produce electrical energy

Answer 9

fuel and oxygen

Question 10

how do hydrogen fuel cells work

Answer 10

hydrogen comes in from the anode and oxygen comes in from the cathode. the hydrogen nucleus passes through the electrolyte and cathode whilst the electrons pass through a separate circuit generating electricity. They then bond with the oxygen on the other side to form H2O then leave through the exhaust