7.1 Exothermic and endothermic reactions + RP

Question 1

Exothermic reaction def

Answer 1

A reaction that transfers energy to the surroundings

Question 2

Endothermic reaction def

Answer 2

A reaction that takes in energy from the surroundings

Question 3

Do endothermic and exothermic reactions cause rises or falls in temperature

Answer 3

Exothermic: temperature rise
Endothermic: temperature fall

Question 4

Examples of exothermic reactions

Answer 4

• burning of fuel (eg combustion of methane)
• neutralisation of acids and alkali

Question 5

Do the products in exothermic reactions have lower or higher energy content than the reactants

Answer 5

Lower

Question 6

How are actual differences in energy measured

Answer 6

Kg/mol

Question 7

Examples of endothermic reactions

Answer 7

• citric acid and sodium hydrogen carbonate
• thermal decomposition

Question 8

Example of thermal decomposition

Answer 8

• decomposition of calcium carbonate
• when heated, it forms calcium oxide and carbon dioxide
• needs to be heated and absorb energy from the surroundings to be broken down

Question 9

Do products in endothermic reactions have a higher or lower energy content than the reactants

Answer 9

Higher

Question 10

Investigating temperature changes method

Answer 10

1. Use the first measuring cylinder to measure 25 cm3 of the sodium hydroxide solution and pour this into the polystyrene cup.
2. Stand the polystyrene cup in the 250 cm3 beaker.
3. In the second measuring cylinder, measure 25 cm3 of hydrochloric acid.
4. Using the thermometer, measure the temperature of the sodium hydroxide every 30 seconds whilst gently stirring.
5. After exactly 2 minutes add the hydrochloric acid and continue to stir and to record the temperature of the solution every 30 seconds for 10 minutes.
6. Repeat this with with 25 cm3 of copper(II) sulfate and iron filings