9 A student investigated the te mperature change in the reaction between dilute sulfuric acid and potassium hydroxide solution.
1 This is the method used.
2 Measure 25.0 cm3 potassium hydroxide solution into a polystyrene cup.
3 Record the temperature of the solution.
4 Add 2.0 cm3 dilute sulfuric acid.
5 Stir the solution.
6 Record the temperature of the solution.
7 Repeat steps 3 to 5 until a total of 20.0 cm3 dilute sulfuric acid has been added.
9-1 Suggest why the student used a polystyrene cup rather than a glass beaker for the reaction.
[2 marks]
ANSWER
Polystyrene is a better thermal insulator so reduces energy exchange with the surroundings.
Table 6 shows some of the student’s results.
Volume of dilute sulfuric acid added in cm3 | Temperature in °C |
0.0 | 18.9 |
2.0 | 21.7 |
4.0 | 23.6 |
6.0 | 25.0 |
8.0 | 26.1 |
10.0 | 27.1 |
Figure 11 shows some of the data from the investigation.
Figure 11
9-2 Complete Figure 11:
plot the data from Table 6
draw a line of best fit through these points
Extend the lines of best fit until they cross.
[4 marks]
ANSWER
9-3 Determine the volume of dilute sulfuric acid needed to react completely with 25.0 cm3 of the potassium hydroxide solution
ANSWER
Volume of dilute sulfuric acid to react completely = 11cm3
9-4 Determine the overall temperature change when the reaction is complete.
Use Figure 11.
[1 mark]
ANSWER
27.6 - 18.9 = 8.7oC
