Tamil Nadu Board of Secondary EducationHSC Science Class 11th

# It takes 192 sec for an unknown gas to diffuse through a porous wall and 84 sec for N2 gas to effuse at the same temperature and pressure. What is the molar mass of the unknown gas? - Chemistry

Numerical

It takes 192 sec for an unknown gas to diffuse through a porous wall and 84 sec for N2 gas to effuse at the same temperature and pressure. What is the molar mass of the unknown gas?

#### Solution

γ_"unknown"/γ_("N"_2) = ("t"_("N"_2))/("t"_"unknown") = sqrt(("M"_("N"_2))/("M"_"unknown"))

(84  "sec")/(192  "sec") = sqrt((28  "g mol"^-1)/"M"_"unknown")

On squaring both sides and rearranging

((84  "sec")/(192  "sec"))^2 = (28  "g mol"^-1)/"M"_"unknown"

"M"_"unknown" = 28  "g mol"^-1 xx ((192  "sec")/(84  "sec"))^2

"M"_"unknown" = 146 g mol−1

Concept: Mixture of Gases - Dalton’S Law of Partial Pressures
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#### APPEARS IN

Tamil Nadu Board Samacheer Kalvi Class 11th Chemistry Volume 1 and 2 Answers Guide
Chapter 6 Gaseous State
Evaluation | Q II. 26. | Page 183
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