Calculate standard enthalpy change of reaction aligned & C ₂ H _ 2( ~g ) + 5 2 O _ 2( ~g ) 2 CO _ 2( ~g ) + H ₂ O _ ( ) if & _ f H ^ ( CO ₂ )=-393 ~kJ ~mol ⁻¹ & _ f H ^ ( H ₂ O )=-286 ~kJ ~mol ⁻¹ & _ f H ^ ( C ₂ H ₂ )=227 ~kJ ~mol ⁻¹ aligne

Question

Calculate standard enthalpy change of reaction aligned & C ₂ H _ 2( ~g ) + 5 2 O _ 2( ~g ) 2 CO _ 2( ~g ) + H ₂ O _ ( ) if & _ f H ^ ( CO ₂ )=-393 ~kJ ~mol ⁻¹ & _ f H ^ ( H ₂ O )=-286 ~kJ ~mol ⁻¹ & _ f H ^ ( C ₂ H ₂ )=227 ~kJ ~mol ⁻¹ aligned

Quantrex Academy · Accepted Answer

Correct answer: C. -1299 ~kJ

The standard enthalpy change for the reaction is calculated using the enthalpy of formation formula: _ r H ^ = n _ f H ^ ( products ) - m _ f H ^ ( reactants ) For the combustion C ₂ H _ 2( g ) + 5 2 O _ 2( g ) 2 CO _ 2( g ) + H ₂ O _ ( ) , substituting the given values yields: _ r H ^ = [2 (-393 kJ ) + 1 (-286 kJ )] - [1 (227 kJ ) + 5 2 (0 kJ )] Simplifying the expression: _ r H ^ = [-786 - 286] - [227 + 0] = -1072 - 227 = -1299 kJ The standard enthalpy change is -1299 kJ , corresponding to answer choice C .

Calculate standard enthalpy change of reaction aligned & C ₂ H _ 2( ~g ) + 5 2 O _ 2( ~g ) 2 CO _ 2( ~g ) + H ₂ O _ ( ) if & _ f H ^ ( CO ₂ )=-393 ~kJ ~mol ⁻¹ & _ f H ^ ( H ₂ O )=-286 ~kJ ~mol ⁻¹ & _ f H ^ ( C ₂ H ₂ )=227 ~kJ ~mol ⁻¹ aligned

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