Required practical - temperature changes inreactingsolutions

• What is the main difference between exothermic and endothermic reactions?

  Exothermic reactions transfer energy to the surroundings, while endothermic reactions take in 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 is the aim of the required practical on temperature changes in reacting solutions?

  • To investigate the variables that affect temperature changes in reacting solutions.
• What is a solution?

  A mixture formed by a solute and a solvent.
• What apparatus is used in the temperature changes practical?

  • Polystyrene cup
  • Thermometer
  • 250 cm³ glass beaker
  • Measuring cylinder
  • Top pan balance
• How would you set up an experiment to investigate the reaction between an acid and an alkali?

  Place the polystyrene cup inside the glass beaker, measure the liquids, and record the temperature before and after mixing.
• What is an independent variable in the context of the temperature changes experiment?

  The variable which is changed during an investigation, typically plotted on the x-axis of a graph.
• What could be an independent variable when investigating temperature changes in a reaction?

  The concentration of one of the reactants or the type of acid/alkali being used.
• What is the method for reacting a solid with a solution in the temperature changes practical?

  1. Place the polystyrene cup inside the glass beaker.
  2. Measure the volume of the solution.
  3. Measure the mass of the solid.
  4. Record the initial temperature of the solution.
  5. Add the solid and record the final temperature.
  6. Change the independent variable and repeat.
• What does a larger temperature change in a reaction indicate?

  The more energy is absorbed or released during the reaction.
• What is the biggest source of error in the temperature changes experiment?

  Unwanted heat transfer.
• What precautions should be taken when handling dilute acids and alkalis?

  • Avoid contact with skin.
  • Rinse off skin if necessary.
  • Wear eye protection.
• What precautions should be taken when disposing of solutions of metal salts?

  • Dispose of as advised by the teacher.
  • Some metal salts should be collected for safe disposal rather than poured down the drain.