For a chemical reaction, if the enthalpy change is ΔH, what is the enthalpy change for the reverse reaction?

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Multiple Choice

For a chemical reaction, if the enthalpy change is ΔH, what is the enthalpy change for the reverse reaction?

Explanation:
Enthalpy change tells whether heat is released or absorbed as reactants become products. When you reverse a reaction, you swap what’s produced and what’s consumed, so the heat flow reverses sign. Since enthalpy is a state function, the magnitude of the energy change stays the same, but the sign flips. Therefore, the enthalpy change for the reverse reaction is the negative of the forward one: -ΔH. If the forward reaction releases heat (negative ΔH), the reverse will absorb the same amount of heat (positive ΔH).

Enthalpy change tells whether heat is released or absorbed as reactants become products. When you reverse a reaction, you swap what’s produced and what’s consumed, so the heat flow reverses sign. Since enthalpy is a state function, the magnitude of the energy change stays the same, but the sign flips. Therefore, the enthalpy change for the reverse reaction is the negative of the forward one: -ΔH. If the forward reaction releases heat (negative ΔH), the reverse will absorb the same amount of heat (positive ΔH).

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