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11. Two gases effuse from a container. The unknown gas requires only 29.9 minutes to effuse the same volume it takes carbon dioxide 37.3 minutes to effuse . What is the gram-molar mass of the unknown gas?
answer: 28 grams per mole

A. Determine the gram-molar mass of the unknown gas,
grams of X per mole of X.

B.  Given: The unknown gas requires 29.9 min. ~ specific volume of gas
                    The CO₂ gas requires 37.3 min. ~ specific volume of gas

Know:

Avogadro's Law:

At the same temperature and pressure, equal volumes of gases
contain the same number of moles of the gases.

Therefore, moles of Unknown gas ~ moles of CO2

Since

moles of Unknown gas ~ moles of CO2
The above equation can be written as

Solving for X yields

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