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Thermodynamics

Question
CBSEENCH11006189

Calculate the heat of reaction 
CH subscript 4 left parenthesis straight g right parenthesis space plus space 4 Cl subscript 2 left parenthesis straight g right parenthesis space rightwards arrow space space space space CCl subscript 4 left parenthesis straight g right parenthesis space plus space 4 HCl left parenthesis straight g right parenthesis if the heats of formation of CH subscript 4 left parenthesis straight g right parenthesis comma space Cl subscript 2 left parenthesis straight g right parenthesis comma space CCl subscript 4 left parenthesis straight g right parenthesis space and space HCl left parenthesis straight g right parenthesis space are comma space
space space minus 74.9 comma space space 0.0 comma space space minus 139.0 space and space minus 92.3 space kJ space mol to the power of negative 1 end exponent respectively.

Solution

Heat of reaction
            increment subscript straight r straight H degree space equals space sum from blank to blank of increment subscript straight f straight H to the power of 0 left parenthesis Products right parenthesis space minus space sum from blank to blank of increment subscript straight f straight H to the power of 0 space left parenthesis Reactants right parenthesis space space space space space space space space
                       equals space open square brackets increment to the power of 0 subscript straight f left parenthesis CCl subscript 4 right parenthesis space plus space 4 increment subscript straight f straight H to the power of 0 left parenthesis HCl right parenthesis close square brackets
space space space space space minus space open square brackets increment subscript straight f straight H to the power of 0 left parenthesis CH subscript 4 right parenthesis space plus space increment subscript straight f straight H to the power of 0 left parenthesis Cl subscript 2 right parenthesis close square brackets
space equals space open square brackets negative 139.0 space plus space 4 left parenthesis negative 92.3 right parenthesis close square brackets space open square brackets negative 74.9 space plus 4 space cross times left parenthesis 0.0 right parenthesis close square brackets
space equals space minus 139.0 space minus 369.2 space plus 74.9 space equals space minus 508.2 space plus 74.9
space space equals space minus 433.3 space kJ