CHAP 13 CHEMICAL ENERGETICS

Question 1

define ENDOTHERMIC REACTION + explanation

Answer 1

a reaction in which thermal energy is taken in, causing a decrease in the temperature of the surrounding.

• the energy level of the product is more than the energy level of reactants. the energy gained by the product is absorbed from the surroundings-> decrease in temperature (surroundings)

Question 2

examples of ENDOthermic reactions [5]:

Answer 2

1) Thermal decomposition
2) dissolving ammonium salt in water (etc. ammonium nitrate)
3) photosynthesis
4) melting, boiling, sublimation
5) atomisation of molecules (bond breaking)

Question 3

define exothermic reaction + explanation

Answer 3

reaction in which thermal energy is given out, causing an increase in the temperature of the surrounding

• the energy level of product is less than the energy of the reactants-> energy lost heats up the surrounding-> increase in temperature (surroundings)

Question 4

what kind of reaction is BOND FORMING? exothermic/endothermic

Answer 4

Exothermic
- when chemical bond is made, heat energy is given out to surrounding

Question 5

examples of EXOTHERMIC reactions[6]:

Answer 5

1) combustion
2) neutralisation
3) displacement reaction
4) respiration
5) condensation, freezing
6) bond forming reactions -> forming compounds

Question 6

practice questions
1) forming a covalent bond
2) melting a solid
3) HCI + KOH -> KCI + H2O
4) mixing methane & oxygen
5) reacting methane & oxygen
6) decomposition of calcium carbonate
7) dissolving ammonium nitrate in water
8) respiration
9) condensing a vapour into liquid

Answer 6

1) exothermic
2) endothermic
3) exothermic
4) neither
5) exothermic
6) endothermic
7) endothermic
8) exothermic
9) exothermic