根据下列信息判断氢气燃烧生成水蒸气时是释放能量还是吸收能量。

根据下列信息判断氢气燃烧生成水蒸气时是释放能量还是吸收能量。____________________

答案

放出能量

解析:破坏旧键(H—H和O—O)消耗能量为436 kJ+249 kJ=685 kJ;形成新键(H—O)释放能量为930 kJ。释放出的比消耗的多930 kJ-685 kJ=245 kJ,可知氢气燃烧生成水蒸气时是释放能量。

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