Question

How many hydrogen atoms are in 89.5 g of C6H6 ? Answer in units of atoms.

Answer 1

Solution :

Molar mass of $C_6H_6$ is :

M = 6×12 + 6×1 g

M = 78 g

78 gram of $C_6H_6$ contains $6.022 \times 10^{23}$ molecules.

So, 89.5 gram of $C_6H_6$ contains :

$n = 6.022 \times 10^{23} \times \dfrac{89.5}{78}\\\\n = 6.91 \times 10^{23}$

Now, from the formula we can see that one molecule of $C_6H_6$ contains 2 hydrogen atom . So, number of hydrogen atom are :

$h = 2\times 6.91 \times 10^{23}\\\\h = 1.38 \times 10^{22}\ atoms$

Hence, this is the required solution.