Question

Water has a mass per mole of 18.0 g/mol, and each water mo- lecule (H2O) has 10 electrons. (a) How many electrons are there in one liter (1.00 x 10-3 m) of water? (b) What is the net charge of all these electrons?

Answer 1

Part 1) Number of electrons in 1 liter of water equals
`N=3.346* 10^(26)`

Part 2) Net charge of all the electrons equals
`Charge=53.61* 10^(6)`

Step-by-step explanation:

Since we know that the density of water is 1 kilogram per liter thus we infer that mass of 1 liter of water is 1 kilogram hence we need to find electron's in 1 kg of water.

Now since it is given that molar mass of water is 18.0 grams this means that 1 mole of water contains 18 grams of water.

Hence by ratio and proportion number of moles in 1 kg water equals

`n=(1000)/(18)`

Now by definition of mole we know that 1 mole of any substance is Avagadro Number of particles.

Hence the no of molecules in 'n' moles of water equals

`n'=(1000)/(18)\cdot N_a\\\\n'=(1000)/(18)\cdot 6.023* 10^(23)\\[\tex][tex]\\n'=3.346* 10^(25)`

Now since it is given that each molecule has 10 electron's thus the total number of electrons in n' molecules equals

`N=10* 3.346* 10^(25)\\\\N=3.346* 10^(26)`

Part 2)

We know that charge of 1 electron equals
`1.602* 10^(-19)C` the the charge of electrons in 'N' quantity equals

`Charge=1.6022* 10^(-19)* 3.346* 10^(26)\\\\Charge=52.61* 10^(6)Columbs`