1Reading a thermometer
Read the scale where the red liquid ends. On this thermometer each small mark is 1 °C.
thermometer
Lesson 17.2 notes
Measuring temperature changes
Reading a thermometer, working out a temperature change, keeping the energy in, and a fair test with four metals.
2Temperature change
Measure the temperature at the start and at the end. Take the start away from the end: 28 − 20 = 8 °C.
temperature change
3A rise or a fall
A rise means energy was given out: exothermic. A fall means energy was taken in: endothermic.
4Keep the energy in
A polystyrene cup with a lid is a good insulator. Less energy escapes, so the temperature change measured is more accurate.
insulator
5A fair test
To compare metals, change only the metal. Keep the acid, its volume and the mass of metal the same.
fair test
6Temperature over time
The temperature rises while the reaction happens, then slowly falls as energy spreads out into the room.
7Repeat and take a mean
Repeat each test. Add up the results and divide by how many there are to find the mean.
mean
Explore: Fair test lab
Add each metal to the acid, first in a polystyrene cup, then in a glass beaker. Compare the temperature rises.
Common mistake: Take the start away from the end
Work out a temperature change by taking the starting temperature away from the final one. If the final temperature is lower, the temperature has fallen.
Remember
- Temperature change = final temperature − starting temperature.
- A rise means energy was given out (exothermic). A fall means energy was taken in (endothermic).
- Use a polystyrene cup with a lid, change only one thing, and repeat each test to take a mean.
Going further at GCSE
GCSE: Temperature changes and their uses → GCSE: The reactivity series →