Question:
If $300\,mL$ of a gas weighs $0.368\, g$ at $STP$. What is its molecular weight?
If $300\,mL$ of a gas weighs $0.368\, g$ at $STP$. What is its molecular weight?
Updated On: Jun 8, 2024
- 30.16 g
- 2.55 g
- 27.5 g
- 37.5 g
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The Correct Option is C
Approach Solution - 1
At STP, $\because$ Weight of $300\, mL$ of gas
$=0.368\, g$
$\therefore$ Weight of $22400\, mL$ of gas
$=\frac{0.368 \times 2240}{300} g / mol$
$=27.47\, g / mol$
$=27.5\, g / mol$
$\because$ Molecular weight of the gas is $27.5\,g$
$[\because 22400\, mL$ of a gas contains amount equal to molecular weight of the gas.]
$=0.368\, g$
$\therefore$ Weight of $22400\, mL$ of gas
$=\frac{0.368 \times 2240}{300} g / mol$
$=27.47\, g / mol$
$=27.5\, g / mol$
$\because$ Molecular weight of the gas is $27.5\,g$
$[\because 22400\, mL$ of a gas contains amount equal to molecular weight of the gas.]
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Approach Solution -2
Ans: Molecular weight is the atomic mass unit of each of the atoms present in the compound.
One mole of gas occupies a volume of 22.4 L at STP ( standard temperature and pressure) where temperature is 273 K and pressure of 1 atm.
Now, according to the question,
Weight of 300ml of the gas is 0.368g
So, weight of 22400 ml of gas will be = 0.368 x 22400/300
= 27.47 g/mol
So, as one mole of gas occupies 22.4L, therefore,the weight will be the molecular weight of the gas.
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