Enthalpy changes that are difficult to measure directly can often be determined using Hess’ Law to construct an enthalpy cycle.
Which enthalpy change is indicated by X in the enthalpy cycle shown?
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+ 1 x Enthalpy of formation of water
- 1 x Enthalpy of formation of water
+ 3 x Enthalpy of formation of water
- 3 x Enthalpy of formation of water
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