An 2.65 g sample of an unknown gas from Group VIIA occupied a volume of 1.64 L at 822 torr and 38 oC. Find the molecular weight of this gas. Show all work.

Answer 1

Based on the information given, you need to use the Ideal Gas law in the format PV =g/M(RT); where g/ M is equivalent to n (the number of moles of the gas) and M is the molar mass of the gas.

Remember original Ideal gas equation is given as PV = nRT .

R is the gas constant and because you are given the pressure in torr, you need to use R = 62.4 L*torr/mol*K; temperature (T) needs to be in kelvin (38+273); and the volume in liters (1.64 L).\

Plugging in the numbers into the formula and solving for M ( units will be g/mol) will give you the molar mass.

PV = g ⁄ M (RT) rearranged gives PVM = gRT

Plugging in the numbers, you should get the molar Mass M = 38.1 g/mol