State and explain the first law of thermochemistry.

1.	State and explain the first law of thermochemistry.
Answer» If enthalpy of formation of a compound is -x kJ, enthalpy of its decomposition intoits elements is + xkJ. Example: C(s) + O₂(g) → CO₂; ΔH = -xkJ According to the law (Lavoisier & Laplae law) CO₂(g) → C(s) + O₂ (g); ΔH = +x kJ

Answer»

If enthalpy of formation of a compound is -x kJ, enthalpy of its decomposition intoits elements is + xkJ.

Example: C(s) + O₂(g) → CO₂; ΔH = -xkJ According to the law (Lavoisier & Laplae law) CO₂(g) → C(s) + O₂ (g); ΔH = +x kJ

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State and explain the first law of thermochemistry.

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