Practicals

Question 1

Describe the practical to investigate variables which affect temperature change

Answer 1

1. Pour 30cm³ of hydrochloric acid into a measuring cylinder then pour this into a polystyrene cup
2. Place a thermometer iinside the cup and measure the starting temperature inside the cup and record this in a table
3. Pour 5cm³ of sodium hydroxide solution into a measuring cylinder, then pour this into the polystyrene cup
4. Place a plastic lid ontop of the polystyrene cup and use the thermometer to gently stir the solution and allow it to react
5. As this is an exothermic reaction the temperature will increase. When the temperature reading on the thermometer stops increasing record this maximum temperature into a table
6. NoW rinse and dry the polystyrene cup and repeat the experiment several more times, increasing the volume of the sodium hydroxide by 5cm³ each time until you reach 40cm³. Record the maximum temperature each time
7. Then repeat everyhting again to get a second set of values. Then calculate a mean maximum temperature for each volume of sodium hydroxide
8. Then use this information to plot a table with the max temperature against the volume of sodium hydroxide

Question 2

What is the independant variable in this experiment?

Answer 2

The volume of sodium hydroxide

Question 3

What is the dependant variable of this experiment?

Answer 3

The maximum temperature

Question 4

What are the control variables in this experiment?

Answer 4

The volume of hydrochloric acid

The concentration of the hydrochloric acid and sodium hydroxide

Question 5

Why are is that a polystyrene cup and plastic lid are used?

Answer 5

Polystyrene and plastic are good insulators
They reduce the amount of heat lost and transferred into the surroundings

Question 6

Name another piece of equipment which can be used to add volumes of sodium hydroxide instead of a measuring cylinder?

Answer 6

A burette

Question 7

Suggest an advantage of using a burette to add volumes of sodium hydroxide instead of a measuring cylinder

Answer 7

It is more accurate

Question 8

Suggest a reason for getting an anomylous result in this experiment

Answer 8

The reaction had not finished

so the maximum temperature recorded would not be accurate