CAIE A-Level Chemistry 5.1.1 Exothermic and Endothermic Changes
Practise assigning the sign of ΔH from heat flow and relative enthalpies of reactants and products.
- Syllabus
- 2028–2030
- Course
- Chemistry 9701
- Level
- AS
Exam points
- state that an exothermic process transfers energy to the surroundings and has negative ΔH
- state that an endothermic process takes in energy from the surroundings and has positive ΔH
- use the defined direction of a reaction or phase change before assigning the sign
5.1.1—Chemical reactions are accompanied by enthalpy question 1
[Maximum number: 1]
One commercially available 'heat pad' contains iron, activated carbon and water. The 'heat pad' is activated by air. This causes the pad to get hotter.
Which statement describes the chemical reaction occurring in the 'heat pad' when it is exposed to air?
A
The reaction is endothermic and iron gains electrons.
B
The reaction is endothermic and iron loses electrons.
C
The reaction is exothermic and iron gains electrons.
D
The reaction is exothermic and iron loses electrons.
D
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