Exothermic and Endothermic - PRACTICAL

Question 1

What is one method to measure the amount of energy released by a chemical reaction?

Answer 1

Taking the temperature of the reactants, mixing them in a polystyrene cup, and measuring the temperature of the solution at the end of the reaction.

This method is practical and straightforward.

Question 2

What is the biggest problem with energy measurements in chemical reactions?

Answer 2

The amount of energy lost to the surroundings.

This loss can affect the accuracy of the measurements.

Question 3

How can you reduce energy loss during measurements?

Answer 3

By placing the polystyrene cup into a beaker of cotton wool for insulation and putting a lid on the cup to reduce evaporation.

These steps help maintain the temperature of the reaction mixture.

Question 4

What types of reactions can the described method be used for?

Answer 4

Neutralisation reactions, reactions between metals and acids, or carbonates and acids.

These reactions typically involve measurable energy changes.

Question 5

What variables can be investigated using this energy measurement method?

Answer 5

The mass or concentration of the reactants used.

Changing these variables can affect the energy transferred.

Question 6

Fill in the blank: To test the effect of gold concentration on the energy released in a neutralisation reaction, you would use _______ and _______ in separate beakers.

Answer 6

hydrochloric acid (HCl) and sodium hydroxide (NaOH).

These two solutions react in the neutralisation process.

Question 7

At what temperature should the water bath be set before starting the experiment?

Answer 7

25 °C.

This ensures both reactants are at the same initial temperature.

Question 8

What should you do after adding hydrochloric acid to the polystyrene cup?

Answer 8

Add sodium hydroxide (NaOH) to the cup with a lid.

This step initiates the neutralisation reaction.

Question 9

How often should you take the temperature of the mixture during the experiment?

Answer 9

Every 30 seconds.

This allows for tracking the temperature change over time.

Question 10

What should you do after recording the highest temperature during the experiment?

Answer 10

Repeat the steps using 0.5 mol/dm³ and then 1 mol/dm³ of hydrochloric acid.

This helps compare the energy released at different concentrations.