Chapter 15 - Energy changes

Question 1

define exothermic

Answer 1

exothermic reaction is a reaction in which heat energy is released to the surroundings (sol)

Question 2

define endothermic

Answer 2

endothermic reaction is a reaction in which heat energy is absorbed from the surroundings (sol)

Question 3

examples of endothermic reactions

Answer 3

• all decomposition reactions
• photosynthesis
• fractional distillation of petroleum
• dissolving ionic compounds in water

Question 4

examples of exothermic reactions

Answer 4

• dissolving acids
• combustion
• neutralisation
• single displacement
• respiration

Question 5

general direction of flow

Answer 5

solid to liquid to gas is endo thermic
the other way is exothermic

Question 6

heat flow in exothermic reaction

Answer 6

heat is given off to the surroundings and the surrounding temperature increases

Question 7

nature of bonds in exothermic

Answer 7

nature of bonds in exothermic is bond forming

Question 8

what is the heat of products - heat of reactants in exothermic

Answer 8

negative

Question 9

general explanation for exothermic reactions

Answer 9

heat of reactants in higher than of the products so total heat given off during bond forming of 2H2O is more than the total heat energy absorbed during bond breaking of 2H2 ad O2
THEREFORE ENERGY IS RELEASED TO SURROUNDINGS

Question 10

heat flow in endothermic reactions

Answer 10

heat is absorbed from the surroundings and the surrounding temperature decreases

Question 11

nature of bonds in endothermic reactions

Answer 11

bond breaking

Question 12

what is the heat of products - heat of reactants in endothermic

Answer 12

positive

Question 13

general explanation for endothermic reactions

Answer 13

heat of reactants is lesser than heat of products so total energy given off during bond forming of 2H2 and O2 is less than total heat energy absorbed during bond breaking of 2H2O molecules
THEREFORE ENERGY IS ABSORBED FROM SURROUNDINGS