Chemistry

Problem

Samples of 14 g of N₂(g) and 16 g of CH₄(g) are mixed in a rigid container at 298 K. Which statement best describes the average molar mass of the resulting gaseous mixture? a) About

22\,\text{g mol}^{-1}

, the simple arithmetic mean of

16

and

28\,\text{g mol}^{-1}

. b) Exactly

16\,\text{g mol}^{-1}

since the lighter gas dominates the mixture. c) Approximately

20\,\text{g mol}^{-1}

; it lies between

16

and

28\,\text{g mol}^{-1}

and is closer to

16\,\text{g mol}^{-1}

because the mixture contains twice as many moles of

\mathrm{CH_4}

as of

\mathrm{N_2}

. d) Nearly

24\,\text{g mol}^{-1}

after (incorrectly) weighting the two molar masses by their gram amounts rather than by their mole amounts.

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