Required Practical 4:Temperature Change

• What type of reaction is being investigated in this practical?

  Exothermic reaction
• What is the purpose of the practical described in the video?

  To investigate the variables that affect temperature changes in chemical reactions
• What are the independent, dependent, and control variables in this experiment?

  • Independent variable: Volume of sodium hydroxide solution
  • Dependent variable: Maximum temperature reached
  • Control variables: Volume of hydrochloric acid, concentrations of hydrochloric acid and sodium hydroxide
• What is the first step in the practical procedure?

  Measure 30 centimeters cubed of dilute hydrochloric acid
• Why is a polystyrene cup used in this experiment?

  To reduce heat loss during the reaction
• What should be done after adding sodium hydroxide solution to the hydrochloric acid?

  Fit a plastic lid to the cup and place the thermometer in the solution
• What happens to the temperature of the solution during the exothermic reaction?

  The temperature of the solution increases
• How is the highest temperature reached recorded?

  When the reading on the thermometer stops changing
• What is the process for repeating the experiment with different volumes of sodium hydroxide?

  1. Measure 10 centimeters cubed of sodium hydroxide solution
  2. Transfer to the polystyrene cup
  3. Stir gently and record the highest temperature
  4. Repeat with increasing volumes up to 40 centimeters cubed
• What trend is observed as the volume of sodium hydroxide solution increases?

  The maximum temperature reached increases
• Why does the maximum temperature start to decrease after a certain volume of sodium hydroxide?

  Because there is not enough hydrochloric acid to react with all the sodium hydroxide
• What is the significance of the energy released being spread out into a greater volume?

  • The energy released is diluted
  • Results in a lower maximum temperature reached
• What is the role of the lid in the experiment?

  To reduce heat loss to the air
• What are the benefits of using a polystyrene cup in this experiment?

  • Good thermal insulator
  • Reduces heat loss through sides and bottom
  • Helps maintain accurate temperature readings