Exo And Endothermic Reactions

Question 1

Conservation of energy

Answer 1

Energy is conserved in chemical reactions. The total amount not energy in the system at the end of the reaction is the same as before the reaction

Question 2

Exothermic reactions

Answer 2

Energy is transferred to the surroundings, increasing the temperature of the surroundings

Question 3

Exothermic reaction examples

Answer 3

-combustion
-neutralisation
-oxidation

Question 4

Endothermic reactions

Answer 4

Energy is taken in from the surroundings, decreasing the temperature of the surroundings

Question 5

Endothermic reaction examples

Answer 5

-thermal decomposition
-athlete ice packs

Question 6

Measuring energy changes in reactions example - calorimeter

Answer 6

1) record starting temperature of water with thermometer
2) stir to spread heat
3) record end temperature of water with thermometer
4) calculate the temperature change (end - start)
5) if the temperature change is positive, the reaction is exothermic, if the temperature change is negative, the reaction is endothermic

Question 7

Exothermic reaction profile diagrams

Answer 7

-reactants start high
-products are lower as energy is released into the surroundings
-activation energy is from the reactants line to the top of the reaction profile
-energy change is from the reactants line to the products line

Question 8

Endothermic reaction profile diagrams

Answer 8

-reactants start low
-products end up higher as energy is taken in from the surroundings
-activation energy is from the reactants line to the top of the reaction profile
-energy change is from the reactants line to the products line