Reactions of metals with dilute acids
3 marks · NormalA student wants to compare the temperature changes when 0.010 mol of three different metals react with 50 cm³ of 1 mol/dm³ hydrochloric acid. She uses 0.24 g magnesium, 0.65 g zinc, and 0.56 g iron. Her results are:
| Metal | Initial temp / °C | Max temp / °C |
|---|---|---|
| magnesium | 20 | 41 |
| zinc | 20 | 28 |
| iron | 20 | 24 |
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21°C (magnesium), 8°C (zinc), 4°C (iron) °C
Common mistakes: Mixing up initial and max temperature; Not subtracting correctly
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Marking points
M1 · 1 mark · Subtracts initial temperature from maximum for each metal.
A1 · 1 mark · Correct value for magnesium: 21°C.
A2 · 1 mark · Correct values for zinc (8°C) and iron (4°C, either value correct for 1 mark).
Worked solution
Temperature change = maximum temperature − initial temperature
For magnesium: 41°C − 20°C = 21°C
For zinc: 28°C − 20°C = 8°C
For iron: 24°C − 20°C = 4°C