Question

What is the no. Of atoms there in 3.2g of CH4

Answer 1

Answer:

0.2 atoms.

Explanation:

given mass =3.2g

molar mass = 16

no. of atoms=

given mass/molar mass

=3.2/16

=0.2 atoms.

Answer 2

We need to find the number of atoms present in 3.2gms of CH4.

Answer:

First we need to find the number of moles present in 3.2 gms of CH4.

Mole:

• Mole is a quantity in chemistry, which corresponds to the mass of substance that contains 6.023×10^23 particles of that substance.
• In other words, Mole is a mass of substance containing same number of fundamental units as there in exactly 12gms of Carbon-12. (12gms of Carbon-12 contains 6.023×10^23 atoms).

Now, the formula to calculate the number of moles of a substance is

no. of moles= weight/ molecular weight

The weight of CH4 given is 3.4gms

Molecular weight of CH4 is

$atomic \: weight \: of \: carbon + 4(atomic \: weight \: of \: hydrogen) \\ = 12 + 4(1) \\ = 12 + 4 \\ = 16$

Therefore, molecular weight of CH4 is 16.

Now number of moles are

$3.4 \div 16 \\ = 0.2$

Therefore, number of moles present in 3.4 gms of CH4 is 0.2mol

Now, we calculate number of molecules present in 0.2 moles.

We know that number of molecules present in 1 Mole of a substance is

$6.023 \times {10}^{23}$

Therefore, number of molecules present in 0.2 moles of a substance is

$0.2 \times 6.023 \times {10}^{23}$

But, we need to find the number of atoms present in 3.2 gms of CH4.

No. of atoms present in 1 molecule of CH4 is 5.

Now, the number of atoms present in 3.2 gms of CH4 is

$5 \times 0.2 \times 6.023 \times {10}^{23} \\ =6.023 \times {10}^{23}$

Therefore, number of atoms present in 3.2 gms of CH4 is

$6.023 \times {10}^{23}$

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