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Write a balanced equation for the reaction of ethanol, CH3CH2OH, with phosphorus trichloride, PCl3, forming ethyl chloride, C2H5Cl and phosphorous acid H3PO3. Calculate the heat of reaction from the standard heats of formation listed below. Then, calculate the standard enthalpy change when 39.2 grams of ethanol is consumed in this reaction. ΔHf°(C2H5OH) = −277 kJ/mol ΔHf°(PCl3) = −287 kJ/mol ΔHf°(C2H5Cl) = −105 kJ/mol ΔHf°(H3PO3) = −972 kJ/mol
Expert Answer
3CH3CH2OH + PCl3 ——————> 3C2H5Cl + H3PO3
ΔH rex = ΔHf°products – ΔHf°reactants
= (-972 +3*-105) -(3*-277 -287)
= -169KJ/mole
3CH3CH2OH + PCl3 ——————> 3C2H5Cl + H3PO3 ΔH rex = -169KJ/mole
3 moles of ethanol react with PCl3 to gives -169KJ/mole
3*46g of ethanol react with PCl3 to gives -169Kj/mole
39.2g of ethanol react with PCl3 to gives = -169*39.2/3*46 = -48Kj/mole
