Question

Calculate the enthalpy change for the process
$CCl subscript 4 left parenthesis straight g right parenthesis space space space rightwards arrow space space straight C left parenthesis straight g right parenthesis space plus space 4 space Cl left parenthesis straight g right parenthesis$
and calculate bond enthalpy of $straight C minus Cl$ in $CCl subscript 4 left parenthesis straight g right parenthesis.$
$increment subscript vap straight H to the power of 0 space left parenthesis CCl subscript 4 right parenthesis space equals space 30.5 space kJ space mol to the power of negative 1 end exponent increment subscript straight f straight H to the power of 0 space left parenthesis CCl subscript 4 right parenthesis space equals space minus 135.5 space kJ space mol to the power of negative 1 end exponent increment subscript straight a straight H to the power of 0 left parenthesis straight C right parenthesis space equals space 715.0 space kJ space mol to the power of negative 1 end exponent comma space where space increment subscript straight a straight H to the power of 0 space is space enthalpy space of space atomisation increment subscript straight a straight H to the power of 0 left parenthesis Cl subscript 2 right parenthesis space equals space 242 space kJ space mol to the power of negative 1 end exponent$

Solution

$straight i right parenthesis space CCl subscript 4 left parenthesis straight l right parenthesis space rightwards arrow space CCl subscript 4 left parenthesis straight g right parenthesis space increment subscript vap straight H to the power of 0 space equals 30.5 space KJ space mol to the power of negative 1 end exponent ii right parenthesis space straight C left parenthesis straight s right parenthesis space rightwards arrow straight C left parenthesis straight g right parenthesis increment subscript straight a straight H to the power of 0 space equals space 715.0 KJ space mol to the power of negative 1 end exponent iii right parenthesis space Cl subscript 2 left parenthesis straight g right parenthesis rightwards arrow 2 Cl left parenthesis straight g right parenthesis space increment subscript straight a straight H to the power of 0 space equals 242 KJ space mol to the power of asterisk times minus 1 end exponent iv right parenthesis space straight C left parenthesis straight g right parenthesis space plus 4 Cl left parenthesis straight g right parenthesis space rightwards arrow CCl subscript 4 left parenthesis straight g right parenthesis space increment subscript straight f straight H equals negative 135.5 KJ space mol to the power of negative 1 end exponent Enthalpy space change space for space the space give space CCl subscript 4 left parenthesis straight g right parenthesis space rightwards arrow straight C left parenthesis straight g right parenthesis space plus 4 Cl left parenthesis straight g right parenthesis can space be space calculated space using space the space following space algebraic space calculation space as colon equation space left parenthesis ii right parenthesis space plus 2 space straight x space equ left parenthesis Iii right parenthesis equals negative equ left parenthesis straight i right parenthesis minus equ left parenthesis iv right parenthesis increment subscript straight a straight H to the power of 0 space left parenthesis straight C right parenthesis space plus space increment subscript straight a straight H to the power of 0 left parenthesis Cl subscript 2 right parenthesis minus increment subscript vap straight H to the power of 0 minus space increment subscript straight f straight H equals left parenthesis 715.0 space KJ space mol to the power of negative 1 end exponent right parenthesis space plus 2 left parenthesis 242 space KJ space mol to the power of negative 1 end exponent right parenthesis space minus left parenthesis 30.5 space mol to the power of negative 1 end exponent right parenthesis minus space space space space left parenthesis negative 135.5 KJ space mol to the power of negative 1 end exponent right parenthesis therefore comma increment straight H equals 1304 space KJ space mol to the power of negative 1 end exponent Bond space enthalpy space of space straight C minus Cl space bond space in space CCl subscript 4 left parenthesis straight g right parenthesis equals 1304 over 4 Kj space mol to the power of negative 1 end exponent equals space 326 space KJ space mol to the power of negative 1 end exponent$ $straight i right parenthesis space CCl subscript 4 left parenthesis straight l right parenthesis space rightwards arrow space CCl subscript 4 left parenthesis straight g right parenthesis space increment subscript vap straight H to the power of 0 space equals 30.5 space KJ space mol to the power of negative 1 end exponent ii right parenthesis space straight C left parenthesis straight s right parenthesis space rightwards arrow straight C left parenthesis straight g right parenthesis increment subscript straight a straight H to the power of 0 space equals space 715.0 KJ space mol to the power of negative 1 end exponent iii right parenthesis space Cl subscript 2 left parenthesis straight g right parenthesis rightwards arrow 2 Cl left parenthesis straight g right parenthesis space increment subscript straight a straight H to the power of 0 space equals 242 KJ space mol to the power of asterisk times minus 1 end exponent iv right parenthesis space straight C left parenthesis straight g right parenthesis space plus 4 Cl left parenthesis straight g right parenthesis space rightwards arrow CCl subscript 4 left parenthesis straight g right parenthesis space increment subscript straight f straight H equals negative 135.5 KJ space mol to the power of negative 1 end exponent Enthalpy space change space for space the space give space CCl subscript 4 left parenthesis straight g right parenthesis space rightwards arrow straight C left parenthesis straight g right parenthesis space plus 4 Cl left parenthesis straight g right parenthesis can space be space calculated space using space the space following space algebraic space calculation space as colon equation space left parenthesis ii right parenthesis space plus 2 space straight x space equ left parenthesis Iii right parenthesis equals negative equ left parenthesis straight i right parenthesis minus equ left parenthesis iv right parenthesis increment subscript straight a straight H to the power of 0 space left parenthesis straight C right parenthesis space plus space increment subscript straight a straight H to the power of 0 left parenthesis Cl subscript 2 right parenthesis minus increment subscript vap straight H to the power of 0 minus space increment subscript straight f straight H equals left parenthesis 715.0 space KJ space mol to the power of negative 1 end exponent right parenthesis space plus 2 left parenthesis 242 space KJ space mol to the power of negative 1 end exponent right parenthesis space minus left parenthesis 30.5 space mol to the power of negative 1 end exponent right parenthesis minus space space space space left parenthesis negative 135.5 KJ space mol to the power of negative 1 end exponent right parenthesis therefore comma increment straight H equals 1304 space KJ space mol to the power of negative 1 end exponent Bond space enthalpy space of space straight C minus Cl space bond space in space CCl subscript 4 left parenthesis straight g right parenthesis equals 1304 over 4 Kj space mol to the power of negative 1 end exponent equals space 326 space KJ space mol to the power of negative 1 end exponent$

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Thermodynamics

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