Question

Calculate the number of hydrogen atoms present in 40g of urea, (NH2)2CO

Answer 1

Answer: There are
`16.14 * 10^(23)` atoms of hydrogen are present in 40g of urea,
`(NH_(2))_(2)CO`.

Step-by-step explanation:

Given: Mass of urea = 40 g

Number of moles is the mass of substance divided by its molar mass.

First, moles of urea (molar mass = 60 g/mol) are calculated as follows.

`Moles = (mass)/(molar mass)\\= (40 g)/(60 g/mol)\\= 0.67 mol`

According to the mole concept, 1 mole of every substance contains
`6.022 * 10^(23)` atoms.

So, the number of atoms present in 0.67 moles are as follows.

`0.67 mol * 6.022 * 10^(23) atoms/mol\\= 4.035 * 10^(23) atoms`

In a molecule of urea there are 4 hydrogen atoms. Hence, number of hydrogen atoms present in 40 g of urea is as follows.

`4 * 4.035 * 10^(23) atoms\\= 16.14 * 10^(23) atoms`

Thus, we can conclude that there are
`16.14 * 10^(23)` atoms of hydrogen are present in 40g of urea,
`(NH_(2))_(2)CO`.