What is the mass in grams of 450 mL of PH3 at STP conditions

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