GCSE Chemistry Revision "Required Practical 4: Temperature Changes"

Summary

This video explains a practical experiment to investigate temperature changes during an exothermic reaction, specifically the neutralization of hydrochloric acid with sodium hydroxide. The experiment measures how the volume of sodium hydroxide affects the maximum temperature reached in the reaction. The process includes varying the sodium hydroxide volume and recording the resulting temperature changes, while controlling other variables. The video demonstrates how, at first, temperature increases as more sodium hydroxide reacts, but eventually decreases due to excess sodium hydroxide and insufficient acid. Key experimental details like using a polystyrene cup to minimize heat loss are also discussed.

Takeaways

• 😀 Investigate variables that affect temperature changes in chemical reactions, specifically in exothermic reactions.
• 😀 The experiment focuses on the neutralization reaction between hydrochloric acid and sodium hydroxide.
• 😀 The independent variable in the experiment is the volume of sodium hydroxide solution added.
• 😀 The dependent variable is the maximum temperature reached during the reaction.
• 😀 Control variables include the volume of hydrochloric acid and the concentrations of both hydrochloric acid and sodium hydroxide solution.
• 😀 The experiment involves adding increasing volumes of sodium hydroxide to hydrochloric acid and measuring the temperature change.
• 😀 A polystyrene cup is used to minimize heat loss during the experiment, ensuring more accurate temperature readings.
• 😀 A thermometer is used to measure and record the temperature rise as the exothermic reaction occurs.
• 😀 As the volume of sodium hydroxide increases, the maximum temperature reached also increases, indicating more energy release.
• 😀 Beyond a certain volume of sodium hydroxide, the maximum temperature starts to decrease due to excess sodium hydroxide and limited hydrochloric acid.
• 😀 In the experiment, large volumes of sodium hydroxide spread the energy over a larger volume, resulting in a lower observed temperature rise.

Q & A

What is the focus of this experiment?

The focus of the experiment is to investigate the temperature change in an exothermic reaction, specifically the neutralization reaction between hydrochloric acid and sodium hydroxide.

What is the independent variable in this experiment?

The independent variable is the volume of sodium hydroxide solution added to the hydrochloric acid.

What is the dependent variable in the experiment?

The dependent variable is the maximum temperature reached during the reaction.

What are the control variables in this experiment?

The control variables are the volume of hydrochloric acid and the concentrations of both hydrochloric acid and sodium hydroxide solution.

Why is a polystyrene cup used in the experiment?

A polystyrene cup is used because it is a good thermal insulator, which helps reduce heat loss through the sides and bottom, ensuring more accurate temperature measurements.

What is the role of the plastic lid during the experiment?

The plastic lid is used to minimize heat loss to the air during the experiment, ensuring that the temperature readings are more reliable.

How is the temperature of the solution measured?

The temperature is measured using a thermometer, which is placed through a hole in the plastic lid, with the bulb of the thermometer submerged in the solution.

What happens to the temperature as more sodium hydroxide is added?

As more sodium hydroxide is added, the maximum temperature reached increases, as the exothermic reaction releases more energy. However, after a certain volume, the temperature starts to decrease.

Why does the temperature decrease when more sodium hydroxide is added beyond a certain point?

The temperature decreases because, after a certain volume of sodium hydroxide, there is not enough hydrochloric acid to react with all the sodium hydroxide. This means some sodium hydroxide doesn't react, and the energy released is spread out over a larger volume.

What is the purpose of repeating the experiment with different volumes of sodium hydroxide solution?

Repeating the experiment with different volumes of sodium hydroxide allows for the collection of multiple data points, which helps to calculate a more accurate mean value for the maximum temperature reached at each volume.