Question

Estimate the number of electrons in 100 g of water. How much is the total negative charge on these electron?

Answer 1

We know that, $1$ mole of a substance contains Avogadro number of atoms/ions/electrons/molecules= $N_A=6.022\times {10}^{23}$

Each molecule of water contain 10 electrons

Mass of $1$ mole of $H_{2}O=18g=10N_A$ number of electrons

Therefore, $1$ gram of $H_{2}O$ contains = $\frac{6.022\times {10}^{24}}{18}$ number of electrons.

So, $100$ gram of $H_{2}O$ contains $=100\times \frac{6.022\times {10}^{24}}{18}$ number of electrons.

Total negative charge carried by these electrons $=\frac{1.6\times {10}^{-19}\times 100\times 6.022\times {10}^{24}}{18}$ coulomb.