How much positive and negative charge is there in a cup of water?

NCERT Example 1.2 How much positive and negative charge is there in a cup of water?

\[H_2 O \Rightarrow 2 \;g + 16 \;g = 18 \; g \]

\[Molar \; mass \; of \; water = 18 \; g\]

\[18 \, g = 1 \; mole\; of \; H_2 O\]

\[1 \, g \Rightarrow \frac{6.02 \times 10^{23}}{18} \, H_2 O \; molecules\]

\[250 \, g \Rightarrow \frac{6.02 \times 10^{23}}{18} \times 250 \; H_2 O \; molecules\]

1 cup is approximately 200 to 300 ml. So assumed 250 ml. 1 L of water is 1 kg. So 250 ml will be 250 g.

8 protons in O and 2 protons in $H_2$, so total 10 protons in $H_2 O$

\[Total \, positive \, charge = \frac{6.02 \times 10^{23}}{18} \times 250 \times 10 \times \left(1.6 \times 10^{-19} \right) \, C \]

\[Total \, positive \, charge = 1.34 \times 10^7 \, C\]

Total negative charge will also be the same as there will be equal no. of protons and electrons. Total or the net charge is zero.