sc19, heat energy changes in chem reac (paper 2)

Question 1

what is an exothermic reaction

Answer 1

• heat energy given out
• reaction mixture or the surroundings increase in tempurature

Question 2

what is an endothermic reaction

Answer 2

• heat energy taken in
• reaction mixture or the surroundings decrease in tempurature

Question 3

what happens to the bonds in a chemical reaction

Answer 3

• the bonds holding the atoms in the molecules of the reactants break
• the atoms then come together in new arrangements to form the products

Question 4

state what is meant by activation energy

Answer 4

minimum energy needed to start a reaction

Question 5

state what is meant by bond energy

Answer 5

energy needed to break 1 mol of a particular covalent bond