Reactions and temperature changes

• What is the difference between exothermic and endothermic reactions?

  Exothermic reactions release energy, while endothermic reactions absorb energy.
• What happens to the temperature of the surroundings during an exothermic reaction?

  The temperature of the surroundings increases.
• What happens to the temperature of the surroundings during an endothermic reaction?

  The temperature of the surroundings decreases.
• What are examples of exothermic reactions?

  • Combustion reactions
  • Oxidation reactions
  • Neutralisation reactions
• What are examples of endothermic reactions?

  • Thermal decomposition reactions
  • Reaction of citric acid and sodium hydrogencarbonate
• What is the definition of an exothermic reaction?

  An exothermic reaction is one in which energy is given out to the surroundings.
• What is the definition of an endothermic reaction?

  An endothermic reaction is one in which energy is taken in from the surroundings.
• What is the significance of energy conservation in chemical reactions?

  • The total amount of energy in the universe remains constant.
  • Energy is transferred to or from the surroundings during reactions.
• What is the unit of measurement for energy?

  Joules (J)
• If a man transfers 100 J of energy while moving a wheelbarrow, how much energy is involved?

  100 J
• Describe the energy changes in the exothermic reaction between sodium hydroxide and hydrochloric acid.

  • Sodium hydroxide solution is mixed with hydrochloric acid.
  • The reaction produces sodium chloride and water.
  • The temperature of the solution increases, indicating an exothermic reaction.
• Describe the energy changes in the endothermic reaction between sodium carbonate and ethanoic acid.

  • Sodium carbonate is mixed with ethanoic acid.
  • The reaction produces sodium ethanoate, water, and carbon dioxide.
  • The temperature of the solution decreases, indicating an endothermic reaction.
• What is the outcome of a neutralisation reaction?

  A neutralisation reaction produces a salt and water.
• What is thermal decomposition?

  Thermal decomposition is a reaction in which a compound breaks down to form two or more substances when heated.
• What is the role of a thermometer in the described reactions?

  The thermometer measures the temperature changes during the reactions.
• How do exothermic and endothermic reactions differ in terms of energy transfer?

  Exothermic reactions transfer energy to the surroundings, while endothermic reactions take energy from the surroundings.