Energy Changes

Question 1

Describe the method of neutralisation

Answer 1

1) place polystyrene cup (for insulation) into a beaker for stability
2) use measuing cylinder to measure 25cm3 of hydrochloric acid into cup
3) insert thermometer bulb into solution and clamp the thermometer
4) put lid on cup (to keep heat in)
5) measure initial temperature
6) add 5cm3 of sodium hydroxide
7) stir mixture and measure temperature (to make sure that all reactants have reacted and that the heat produced has spread throughout the mixture)
8) repeat steps 6-7 until 40cm3 of NaOH is added

Question 2

What are the expected results of neutralisation?

Answer 2

• temp rises with each addition until all acid is reacted
• further addtions cool solution down

Question 3

What is the activation energy?

Answer 3

• minimum amount of energy particles need to react

Question 4

What is an exothermic reaction?

Answer 4

• reaction that releases energy into the surroundings
• temperature of surroundings increase

Question 5

What is an endothermic reaction?

Answer 5

• reaction that takes in energy from the surroundings
• temperature of surroundings decrease

Question 6

What happens when bonds are made?

Answer 6

• energy is given out

Question 7

What happnens when bonds are broken?

Answer 7

• energy is taken in

Question 8

What is the formula for energy change?

Answer 8

energy of bonds broken - energy of bonds made

negative result = exothermic
positive result = endothermic