The reaction of chlorine gas with solid phosphorus ( $P_4$ ) produces solid phosphorus pentachloride. When 160 of chlorine reacts with 23.0 g of $P_4$ , which reactant is limiting? Which reactant is in excess?

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Answer 1 · 2016-05-12T13:24:56

We need a balanced chemical equation, before we determine the reagent in excess. I think it is chlorine gas.

$1/4P_4 +5/2Cl_2 rarr PCl_5$

This is of course a redox reaction, and establishes the stoichiometry. One equiv of phosphorus is oxidized by $5/2$ equiv of chlorine gas.

$"Moles of phosphorus ATOMS"$ $=$ $(23.0*g)/(31.00*g*mol^-1)$ $=$ $0.742*mol$ .

$"Moles of chlorine ATOMS"$ $=$ $(160.0*g)/(35.45*g*mol^-1)$ $=$ $4.51*mol$ .

Clearly, phosphorus is in deficiency, and 100% yield would give rise to $0.742*mol$ $PCl_5$ (which of course contains $3.71$ $mol$ chlorine.

The reaction of chlorine gas with solid phosphorus (P_4P_4) produces solid phosphorus pentachloride. When 160 of chlorine reacts with 23.0 g of P_4P_4, which reactant is limiting? Which reactant is in excess?