Question #41182

1 Answer
Stefan V.
Jul 2, 2015

You'd need 87.5 g of chlorine gas.

Explanation:

The balanced chemical equation for this reaction looks like this

#P_(4(s)) + color(red)(6)Cl_(2(g)) -> color(blue)(4)PCl_(3(l))#

Chlorine and phosphorus trichloride have a #color(red)(3):color(blue)(2)# mole ratio, which means that the reaction will always need 3/2 times more moles of chlorine gas than the number of moles of phosphorus trichloride produced.

So, in order to produce 0.823 moles of phosphorus trichloride, the reaction needs

#0.823cancel("moles"PCl_3) * (color(red)(3)" moles "Cl_2)/(color(blue)(2)cancel("moles"PCl_3)) = "1.2345 moles"# #Cl_2#

To get the mass in grams that would contain this many moles, use chlorine gas' molar mass

#1.2345cancel("moles" Cl_2) * "70.906 g"/(1cancel("mole"Cl_2)) = "87.533 g"#

Rounded to three sig figs, the number of sig figs you gave for the number of moles of phosphorus trichloride produced, the answer will be

#m_(Cl_2) = color(green)("87.5 g")#

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