Required Practical: Investigating Temperature Changes in Chemical Reactions

Aim

Investigating the factors that influence temperature changes in chemical reactions, specifically the reaction between an acid and an alkali.

Apparatus

  • 250 cm³ glass beaker
  • Polystyrene cup
  • 25 cm³ measuring cylinder
  • Thermometer

Method

1. Place a polystyrene cup inside a glass beaker.

2. Use a measuring cylinder to place 25 cm³ of sodium hydroxide NaOH in the cup.

3. Measure the temperature of the NaOH with a thermometer and record it in a table.

4. Use a measuring cylinder to add 5 cm³ of hydrochloric acid (HCl) to the cup.

5. Record the highest temperature reached by the mixture in a table.

6. Repeat steps 1-5, but increase the amount of acid added by 5 cm³ each time.

Results

Record your results in an appropriate table. For example:

Volume of hydrochloric acid added (cm³)Maximum temperature (°C)
516
1017
1518

To ensure repeatable outcomes, the practical should be repeated to eliminate anomalies and take the mean of the results.

Conclusion

The amount of acid added directly influences the temperature change in the reaction between an acid and an alkali. A greater temperature change indicates more energy absorption or release.

Evaluation

The biggest source of error in this experiment is usually unwanted heat loss to the surroundings. To reduce this, a lid should be used.

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