At 80.°C, Kc = 1.87 10-3 for the reaction.

Question

PH3BCl3(s) PH3(g) + BCl3(g)
(a) Calculate the equilibrium concentrations of PH3 and BCl3 if a solid sample of PH3BCl3 is placed in a closed vessel at 80.°C and decomposes until equilibrium is reached.
(b) If the flask has a volume of 0.450 L, what is the minimum mass of PH3BCl3(s) that must be added to the flask in order to achieve equilibrium?

Answer 1

Kc=[PH3][BCl3]

since those are both equal concentratons, then

x^2=Kc
x= sqrt Kc

b. mass of PH3+massBCl3=2xVolume=2*.450*sqrtKc

Answer 2

thnx :)

Answer 3

why do both PH3 and BCL3 have equal concentrations at equilibrium?

Answer 4

Same leading digit, one mole each