Question

at STP if 1 gram of gas has the weight of an 140 ml then what is the molecular weight of that gas??​

Answer 1

Given that,

• 1 g of a gas has the weight of 140 ml.

We have to find,

• Molecular weight of the gas.

It is given in the question that 1 g of some gas has the weight of 140 ml,

Let us find the number of moles of the gas of 1 g,

Which can be calculated as,

⇒ Number of moles = Volume / 22.4

At STP.

⇒ Number of moles = (140/1000) / 22.4

Because the volume of 1 g gas is given in ml, so we have to convert that into Litres.

⇒ Number of moles = 0.14 / 22.4

⇒ Number of moles = 0.00625

⇒ Number of moles = 6.25 × 10⁻³ mole

Now the weight of the gas of 140 ml is given to be 1 g, So

⇒ Number of moles = Mass / Molar mass

⇒ 6.25 × 10⁻³ = 1 / m

⇒ m = 1 / (6.25 × 10⁻³) g

⇒ m = 1000 / 6.25

⇒ Molar mass, m = 160 g

Hence, The molecular(molar mass) of the given gas is 160 g.

Answer 2

Answer:

Given that,

1 g of a gas has the weight of 140 ml.

We have to find,

Molecular weight of the gas.

It is given in the question that 1 g of some gas has the weight of 140 ml,

Let us find the number of moles of the gas of 1 g,

Which can be calculated as,

⇒ Number of moles = Volume / 22.4

At STP.

⇒ Number of moles = (140/1000) / 22.4

Because the volume of 1 g gas is given in ml, so we have to convert that into Litres.

⇒ Number of moles = 0.14 / 22.4

⇒ Number of moles = 0.00625

⇒ Number of moles = 6.25 × 10⁻³ mole

Now the weight of the gas of 140 ml is given to be 1 g, So

⇒ Number of moles = Mass / Molar mass

⇒ 6.25 × 10⁻³ = 1 / m

⇒ m = 1 / (6.25 × 10⁻³) g

⇒ m = 1000 / 6.25

⇒ Molar mass, m = 160 g

Hence, The molecular(molar mass) of the given gas is 160 g.

Explanation:

Hope this answer will help you.