CH-1249

Exothermic and endothermic reactions

Chemistry · Secondary 4 · Hard · Exothermic and endothermic reactions

Hydrogen burns in oxygen to form water:

2H_2(g) + O_2(g) \rightarrow 2H_2O(l)

.

This reaction is exothermic. Which statement about the enthalpy change,

\Delta H

, and energy transfer is correct?

$\Delta H$ is negative; energy is released to the surroundings and the temperature increases.
$\Delta H$ is positive; energy is released to the surroundings and the temperature increases.
$\Delta H$ is negative; energy is absorbed from the surroundings and the temperature decreases.
$\Delta H$ is positive; energy is absorbed from the surroundings and the temperature decreases.

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