187
Question
Using the data provided, calculate the multiple bond energy (kJmol−1) of a C≡≡C bond in C2H2. Given that the heat of formation of C2H2 is 225kJmol−1 (take the bond energy of a C−−H bond as 350kJmol−1)
2C(s)⟶2C(g);ΔH=1410kJmol−1
H2(g)⟶2H(g);ΔH=330kJmol−1
Using the data provided, calculate the multiple bond energy (kJmol−1) of a C≡≡C bond in C2H2. Given that the heat of formation of C2H2 is 225kJmol−1 (take the bond energy of a C−−H bond as 350kJmol−1)
2C(s)⟶2C(g);ΔH=1410kJmol−1
H2(g)⟶2H(g);ΔH=330kJmol−1
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Solution
The correct option is D 815
The heat of formation of C2H2 is 225kJmol−1 (take the bond energy of a C−−H bond as 350kJmol−1) :
(i) 2C(s)+H2(g)⟶H−C≡H(g);ΔH=225kJmol−1
(ii) 2C(s)⟶2C(g);ΔH=1410kJmol−1
(iii) H2(g)⟶2H(g);ΔH=330kJmol−1
From equation (i) :
225=[2×ΔC(s)→C(g)+1×eH−−H]−[2×eC−−H+1×eC≡≡C]
225=[1410+1×330]−[2×350+1×eC≡≡C]
225=[1410+330]−[700+eC≡≡C]
225=1740−700−eC≡≡C
eC≡≡C=1040−225=815kJmol−1
BEC≡≡C=815kJmol−1
The multiple bond energy (kJmol−1) of a C≡≡C bond in C2H2 is 815kJmol−1.
The heat of formation of C2H2 is 225kJmol−1 (take the bond energy of a C−−H bond as 350kJmol−1) :
(i) 2C(s)+H2(g)⟶H−C≡H(g);ΔH=225kJmol−1
(ii) 2C(s)⟶2C(g);ΔH=1410kJmol−1
(iii) H2(g)⟶2H(g);ΔH=330kJmol−1
From equation (i) :
225=[2×ΔC(s)→C(g)+1×eH−−H]−[2×eC−−H+1×eC≡≡C]
225=[1410+1×330]−[2×350+1×eC≡≡C]
225=[1410+330]−[700+eC≡≡C]
225=1740−700−eC≡≡C
eC≡≡C=1040−225=815kJmol−1
BEC≡≡C=815kJmol−1
The multiple bond energy (kJmol−1) of a C≡≡C bond in C2H2 is 815kJmol−1.
The multiple bond energy (kJmol−1) of a C≡≡C bond in C2H2 is 815kJmol−1.
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