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05/10/2020 5:25 pm
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The heat of combustion of yellow phosphorous is – 9.91 kJ and of red phosphorous is – 8.78 kJ. The heat of transition of yellow phosphorus to red phosphorus is :
(a) – 9.91 kJ
(b) – 8.78 kJ
(c) – 9.34 kJ
(d) – 1.13 kJ
1 Answer
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05/10/2020 5:43 pm
(d) – 1.13 kJ
Explanation:
P(red) + 5/2O2 → P2O5; ΔH = -8.78
P(yellow) + 5/2O2 → P2O5; ΔH = -9.91
P(red) + 5/2O2 - 5/2O2 → P2O5 - P2O5
P (Red) – P (Yellow) = 0;
ΔH = -8.78 + 9.91 = 1.113
P(red) → P(yellow), ΔH = 1.113
P(yellow) → P(red), ΔH = -1.113