8. energy changes in reactions

Question 1

exothermic reaction

Answer 1

give out thermal energy to their surroundings

Question 2

exothermic energy level diagram

Answer 2

the products have less energy than the reactants do so energy has been given out

Question 3

endothermic reactions

Answer 3

take in thermal energy from their surroundings

Question 4

endothermic energy level diagram

Answer 4

the products have more energy than the reactants do so energy has been taken in

Question 5

reaction pathway diagrams

Answer 5

google or tb check kar

Question 6

activation energy

Answer 6

is the minimum energy that colliding particles must have in order to react

Question 7

enthalpy change in a reaction

Answer 7

energy in for bond breaking - energy out from bond making

Question 8

bond energy

Answer 8

is the energy needed to break bonds or released when the same bonds form (kJ/mol)

Question 9

hydrogen-oxygen fuel cell

Answer 9

uses hydrogen and oxygen to produce electricity where the only chemical product is water

Question 10

hydrogen-oxygen fuel cell redox reaction

Answer 10

(check tb image + adv disadv)
hydrogen gives up electrons at anode and is oxidised : 2H2 –> 4H+ + 4e-
oxygen accepts electrons at cathode and is reduced : o2 + 4H+ + 4e- –> 2H2O