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Question
Calculate the entropy change in surroundings when 1.00 mol of H2O(l) is formed under standard conditions. ΔfHθ = –286 kJ mol–1.
Solution
It is given that 286 kJ mol–1 of heat is evolved on the formation of 1 mol of H2O(l). Thus, an equal amount of heat will be absorbed by the surroundings.
qsurr = + 286 kJ mol–1
Entropy change (ΔSsurr) for the surroundings = `"q"_"surr"/7`
`= (286" kJ mol"^(-1))/298 k`
∴ ΔSsurr = 959.73 J mol-1 K-1
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