Energetics and Equilibria

Question 1

What is an exothermic reaction?

Answer 1

• a reaction which gives out energy to the surroundings, usually in the form of heat and shown by a rise in temperature

Question 2

What is an endothermic reaction?

Answer 2

• a reaction which takes in energy from the surroundings usually in the form of heat and is shown by a fall in temperature

Question 3

What process is bond breaking?

Answer 3

• endothermic

- energy must be supplied to break existing bonds

Question 4

What process is bond formation?

Answer 4

• exothermic

- energy is released when new bonds are formed

Question 5

What is the value of an exothermic and endothermic reaction?

Answer 5

• exothermic: negative because reaction is giving out energy
• endothermic: positive because the reaction takes in energy

Question 6

What is the equation to calculate enthalpy change?

Answer 6

• total energy absorbed to break bonds - total energy released in making bonds

Question 7

Describe dissolving, displacement, and neutralisation calorimetry reactions

Answer 7

• take the temperature of the reagents ( make sure they’re the same), mix and measure the temperature at the end of the reaction or at intervals

Question 8

Describe combustion calorimetry reactions

Answer 8

• put 50g of water in a copper can and record its temperature
• weigh spirit burner and lid
• heat the water until 50 degrees
• measure temperate of water
• weigh spirit burner and lid

Question 9

What is a reversible reaction?

Answer 9

• a reaction where the products of the reaction can themselves react to produce the original reactants

Question 10

What is dynamic equilibrium?

Answer 10

• a reversible reaction that take place under closed conditions can reach a dynamic equilibrium
• both reactions are occurring
• but the overall quantities of the substances remain the same