Question

Calculate the total number of electrons present in a pure sample of $H_{2}S{O}_4,$ if 5 moles of oxygen are present in the sample.

• A. $1.51\times {10}^{26}$
• B. $3.76\times {10}^{26}$
• C. $1.51\times {10}^{25}$
• D. $3.76\times {10}^{25}$

Answer 1

The correct option is D $3.76\times {10}^{25}$

From the formula unit of $H_{2}S{O}_4,$
4 moles of O-atoms are present in 1 mole of $H_{2}S{O}_4$. Therefore, 5 moles of O-atom will be present in $\frac{5}{4}$ moles of $H_{2}S{O}_4$.

The total number of electrons in one formula unit of $H_{2}S{O}_4=1\times 2+16+8\times 4=50$

The total number of electrons in one mole of $H_{2}S{O}_4=50\times 6.022\times {10}^{23}$

Therefore, the total number of electrons in $\frac{5}{4}$ moles of $H_{2}S{O}_4$
$=50\times 6.022\times {10}^{23}\times \frac{5}{2}$
$=3.76\times {10}^{25}$