A 10.0g sample of phosphorus, P4 is reacted with chlorine gas to form phosphorus(III)chloride, PCl3(g). The enthalpy change for the reactio?

35. A 10.0g sample of phosphorus, P4(s) is reacted with chlorine gas to form phosphorus(III)chloride, PCl3(g). The enthalpy change for the reaction is -23.2 kJ. Write the equation for the standard molar enthalpy of formation ΔHf for PCl3(g).

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  • 8 months ago

    P4 + 6 Cl2 → 4 PCl3

    (10.0 g P4) / (123.895048 g P4/mol) x (4 mol PCl3 / 1 mol P4) = 0.322854 mol PCl3

    (-23.2 kJ) / (0.322854 mol PCl3) = -71.859 kJ/mol PCl3

    1/4 P4 + 3/2 Cl2 → PCl3, ΔH = -71.9 kJ

    or

    P4 + 6 Cl2 → 4 PCl3, ΔH = -287 kJ

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