A student investigates some exothermic and endothermic reactions.
Look at his table of results.
Reaction | Temperature at start (°C) | Temperature at end (°C) | Temperature change (°C) |
1 | 15 | 25 | +10 |
2 | 15 | 15 | 0 |
3 | 18 | 15 | -3 |
4 | 15 | 20 | +5 |
What can you conclude about the type of energy change in each reaction?
Explain your answer.
At the end of the reaction, he removes the thermometer from the beaker and measures the temperature.
How should he improve his method? Explain your answer.
A student adds water to calcium oxide. A vigorous exothermic reaction takes place forming calcium hydroxide.
Calcium hydroxide has the formula Ca(OH)2.
Show that the relative formula mass (Mr) of calcium hydroxide is 74.1.
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