The mass in grams of 450 ml of PH3 at STP condition is 0.6794 grams
Explanation
mass PH3= molar mass of PH3 x moles of PH3
molar mass = 30.97 +(1x3)= 33.97g/mol
find the number of moles of PH3 at STP
at STP 1 moles = 22.4 L
convert 450 ml to liters = 450/1000 =0.45 L therefore what about 0.45 L
= (1mole x 0.45L)/22.4l = 0.02 moles
mass is therefore = 0.02 moles x 33.97 = 0.6794 grams
