What is the molecular mass of a compound if 560mL have a mass of 1.10g at STP?

1 Answer
Apr 29, 2016

Answer:

#M_r = 44.6#.

Explanation:

We can use the Ideal Gas Law to solve this problem.

#color(blue)(|bar(ul(color(white)(a/a)PV = nRT color(white)(a/a)|)))" "#

Since #n = "mass"/"molar mass" = m/M#, we can write the Ideal Gas Law as

#PV = m/MRT#

We can rearrange this to

#M = (mRT)/(PV)#

At STP, #P = "1 bar"# and #T = "0 °C"#.

#M = ("1.10 g" × 8.314 × 10^"-2" color(red)(cancel(color(black)("bar·L·K"^"-1")))"mol"^"-1" × 273.15 color(red)(cancel(color(black)("K"))))/(1 color(red)(cancel(color(black)("bar"))) × 0.560 color(red)(cancel(color(black)("L")))) = "44.6 g/mol"#

#M_r = 44.6#