Question

Positive and negative charge on 18cc of water is

Answer 1

amount of water = 18cc = 18mL [ 1cc = 1mL ]
we know, density of water = 1 g/mL
so, mass of given amount of water = density × volume = 18mL × 1 g/mL = 18g
we also know, Molecular weight of water , H₂O = 18g/mol
so, number of moles of water = weight/Molecular weight = 18/18 = 1 mol
In water , H₂O there are 10 electrons [ 2 of Hydrogen atoms and 8 of oxygen atom ]
so, number of moles of electrons in 1 mole of water = 10 × 1 = 10
now, number of electrons = number of moles × Avogadro's number
= 10 × 6.023 × 10²³ = 6.023 × 10²⁴

We know, charge on an electron = 1.6 × 10⁻¹⁹ C
so, charge on 6.023 × 10²⁴ electrons = 6.023 × 10²⁴ × 1.6 × 10⁻¹⁹ C
= 9.632 × 10⁵ C

Because you know water is neutral molecule , it means positive charge and negative charge will be same amount .
Hence, positive charge = 9.632 × 10⁵C
negative charge = -9.632 × 10⁵C

Answer 2

Given amount of water =18cc =18ml [ 1cc=1ml]

As we know that Density=mass/volume

Mass= density x water =1x18 =18g [ since density of water=1gm/cc]

Mass of water=18g

Molecular mass of water=18g

1mole [18g] contains 6.023x 10²³ molecules

18 g contains ----------?

number of molecules in 18g of H20= 18X6.023x 10²³ /18 
=6.023x 10²³  

As one molecule of H2O contains 2 hydrogen atoms and 1 oxygen atoms.

And as water is a neutral molecule. That means number of electrons= number of protons.

Number of electrons=8+1+1 =10
Total positive charge = Total negative charge as water is neutral.

Number of electrons in 18 g of water =6.023x 10²³ x10
=6.023x10²⁴

Charge on one electron=1.6x10⁻19 C

∴ Total charge if 18g of water= Q=ne

=6.023x10²⁴x1.6 x 10⁻¹⁹
=6.023 x1.6 x10⁵
 =9.63x10⁵C
∴ Total positive charge = Total negative Charge=9.63x10⁵C