Question

calculate the number of molecules present in 6 grams of water

Answer 1

The molecular mass of water molecule is 18 g/mol. It implies that 1 mol of water molecules weigh 18 g.

Now you can calculate easily the number of water molecules present in 1 g of water. Calculation follows

18 g of water contain 1 mol of water molecules.

or 18 g of water contain 6.022 x 10^23 water molecules.

or 1 g of water contains (6.022 x 10^23)/ 18 water molecules and the number comes out to be 3.3455 x 10^22.

So the number of water molecules present in 1 g of water is 3.3455 x 10^22.

Hope you got the answer of your question.

Now you will be very much surprised to know the number of water molecules you consume each hour, each day and each week and so on…… It’s quite interesting. Isn’t it ?

Answer 2

The number of molecules present in 6 grams of water is 2 × 10²³ molecules.

Given:

6 grams of water.

To Find:

The number of molecules present in 6 grams of water.

Solution:

To find the number of molecules present in 6 grams of water we will follow the following steps:

As we know,

$number \: of \: moles \: = \frac{given \: mass}{molecular \: mass}$

$number \: of \: moles \: present \: in \: 6g \: of \: water \: = \frac{6}{18} = \frac{1}{3} moles$

1 mole of any substance contains 6.022 × 10²³ molecules.

So,

$Number \: of \: molecules \: present \: in \frac{1}{3} moles \: \: of \: water = \frac{1}{3} \times 6.022 \times {10}^{23} = 2.00 × 10²³$

Henceforth, the number of molecules present in 6 grams of water is 2 × 10²³ molecules.

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