Question

A gas cylinder filled with hydrogen holds 50g of the gas. The same cylinder holds 200g of a gas X and 500 g of gas Y.
Considering the same conditions calculate the relative molecular masses of gases X and Y.
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Answer 1

Required answer:–

Given:–

• Amount of gas holded by hydrogen filled cylinder = 50g

• Amount of gas X holded by cylinder = 200g

• Amount of gas holded by cylinder Y = 500g

To find:–

• Relative molecular masses of gases X and Y

As we know:–

$\bold\pink{vapour \:density \: of \: a \: gas \: = \dfrac{mass \: of \: certain \: volume \:of \: a \: gas \: at \: S.T.P. }{mass \: of \: an \: equal \: volume \: of \:H2 \: at \ S.T.P. } }$

Step by step explaination:–

First calculating the vapour density for gas X...

That is,

$\dfrac\pink{\cancel{200}}\pink{\cancel{50}}$

$\pink4$

Now calculating the vapour density for gas Y...

That is,

$\dfrac\pink{\cancel{500}}\pink{\cancel{50}}$

$\pink1\pink0$

______________________________________

Calculating the relative molecular mass of gas Y...

That is,

$\bold\pink{2 \times Vapour \: density}$

$\bold\pink{2 \times10 }$

$\pink{20}$

Calculating the relative molecular mass of gas X...

That is,

$\bold\pink{2 \times vapour \: density}$

$\bold\pink{2 \times 4}$

$\bold\pink{8}$

Answer:

Relative molecular mass of gas X is 8

Relative molecular mass of gas Y is 20

Extra information:-

• Molecular formula is a chemical formula which gives the actual number of atoms of the elements present in one molecule of a compound.

• The relative molecular mass of a gas is twice its vapour density.

• The relative atomic mass of an element is the number of times one atom of the element is heavier than 1/12 times of the mass of an atom of carbon-12.

• The molecular mass of a substance is expressed in grams is called gram molecular mass or molar mass.

• The molar volume of a gas can be defined as the volume occupied by one mile of a gas at S.T.P.

Answer 2

Explanation:

Relative molecular mass of gas X is 8

Relative molecular mass of gas Y is 20