Question

A laboratory group measures an excess of a volatile liquid. They add this to an empty flask with a volume of 66 mL. They heat the sample to 86.9 degrees Celcius until all the liquid is vaporized. The pressure in the lab is 0.987 atm. If 0.287 grams of volatile liquid were left in the flask, what was the molar mass of the compound?

Answer 1

130.159

Step-by-step explanation:

P=0.987

V=66ml =66/1000=0.066 L

n/moles= ?

R=0.08206

T=86.9+273.15=360.5 K

Formula PV=RnT

n =PV/TR

n=(0.987 * 0.066)/(360.05 * 0.08206) = 0.002205

Now to obtain molar mass you divide grams by mol.

0.287/0.002205 = 130.159