Temperature Changes

Question 1

What is the purpose of this practical?

Answer 1

Investigate the variables that affect temperature change in chemical reactions.

Question 2

How does this practical work?

Answer 2

Investigating temp change in exothermic (Neutralisation) reaction between HCl acid and Sodium Hydroxide.
Add increasing volumes of sodium hydroxide solution to hydrochloric acid and measure maximum temperature reached.

Question 3

What are the variables within this practical?

Answer 3

Independent - Volume of sodium hydroxide
Dependent - Max temp reached
Control - Volume of HCl and concentrations of HCl and Sodium hydroxide solution

Question 4

What is the method for this practical?

Include terms such as: Measuring cylinder, Polystyrene cup, Beaker, Thermometer,

Answer 4

1. Use measuring cylinder to measure 25cm^3 of dilute hydrochloric acid into polystyrene cup.
2. Place cup into beaker for stability
3. Measure and record initial temperature of HCl using thermometer.
4. Measure 5cm^3 of sodium hydroxide solution to cup and quickly add lid and put thermometer through hole of lid.
5. Stir solution and record temperature once reading on thermometer become constant.
6. Repeat steps 4 and 5 7 more times until a total of 40cm^3 of sodium hydroxide has been added to the cup.
7. Repeat entire experiment to ensure reliability of results and to calculate mean maximum temperature reached for each volume of sodium hydroxide added.

Question 5

What are the results of this practical?

Answer 5

As volume of sodium hyroxide increases so does maximum temperature reached.
When graphed, if max temp decreases, there was not enough HCl to react with all sodium hydroxide.

Question 6

Why is a polystyrene cup and lid used?

Answer 6

Good thermal insulator which reduces heat loss.
Lid reduces heat loss to the air.