.25 g of each of the following gasses are taken at 27°C and 600 mm Hg pressure. Which of these will have the least volume?
(Molar mass (g/mole): HCI = 36.5, HBr = 81, HI = 128, HF = 20)
(R=0.082 Latm/K. mole)
A. HC1
B. HBr
C. HI
D. HF

HI has the least volume

Given

Gasses and molar mass

Required

The least volume

Solution

Ideal gas law

PV=nRT

V = (nRT)/P

n = mass : MW(Molar weight=molar mass)

so V is inversely proportional to MW(molar mass)

Because the values of P, R, T, and mass are the same, what matters is the value of the molar mass of each compound. The larger the molar mass the smaller the volume

From the available molar mass data, HI has the largest molar mass, so HI has the smallest volume

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).