Temperature Changes During Neutralisation

Question 1

Describe a method for this practical.

Answer 1

1. Measure 30 cm3 dilute hydrochloric acid and put it into the polystyrene cup.
2. Stand the cup inside the beaker. This will make it more stable
3. Use the thermometer to measure the temperature of the acid. Record your results
4. Measure 5 cm3 sodium hydroxide solution.
5. Pour the sodium hydroxide into the polystyrene cup. Fit the lid and gently stir the solution with the thermometer through the hole.
6. Look carefully at the temperature rise on the thermometer.
7. When the reading on the thermometer stops changing, record the highest temperature reached in the table.
8. Repeat steps 4–7 to add further 5 cm3 amounts of sodium hydroxide to the cup each time, recording your temperature reading in the results table.
9. Repeat until a maximum of 40cm3 of sodium hydroxide has been added.
10. Wash out all the equipment and repeat the experiment for your second trial

Question 2

What is the independent variable?

Answer 2

Volume of sodium hydroxide added to

Question 3

What is the dependant variable?

Answer 3

Temperature

Question 4

Why is a beaker and lid used?

Answer 4

To reduce heat loss

Question 5

What are some control variables?

Answer 5

Volume of acid
Same thermometer
Same concentration of solutions
Same material

Question 6

What is the word equation for the reaction between sodium hydroxide and hydrochloric acid?

Answer 6

Hydrochloric acid + Sodium hydroxide→Sodium Chloride + Water

Question 7

Why does temperature decrease after a while?

Answer 7

The acid had been neutralised so most of energy had been released. After this point sodium hydroxide was just decreasing temperature and diluting it so reduced rate of reaction.