Question

How many positive and negative charge are there in cup of water?

Answer 1

Let us consider 1 cup = 250 mL = 250g

We know Density of Water = 1 \ \frac{g}{cc} (or) 1 \ \frac{g}{mL^3}

where g=grams, cc= centimeter cube, mL= mili litre

 

We know the formula of water is {{H}__2}O

Therefore in 18g of {{H}__2}O there are 8 protons and 8 electrons.

=> The number of protons and electrons each in 250 g of water are \frac{8\ast250}{18}\approx 111

=> There are 111 protons and 111 electrons in 250 mL of water

We know charge of 1 electron = -1.6\ast10^{-19} \ C and

charge of 1 proton =  +1.6\ast10^{-19} \ C

 

Therefore  

positive charge in a cup of water = 111\ast(+1.6\ast10^{-19})\approx+118\ast10^{-19}=+1.18*10^{-17} C

and

positive charge in cup of water = 111\ast(-1.6\ast10^{-19})\approx-118\ast10^{-19}=-1.18*10^{-17} C