Question

the total number of electrons present in 18g of H2O

Answer 1

1 molecule of H2O has 2+8electrons=10electrons
Thus 6.023 x 10^(23) molecules of water will contain 10 x 6.023 x 10^(23) electrons= 6.023 x 10^(24) electrons.

Answer 2

Given: Mass of water, m = 18g

To Find: Total number of electrons, N.

Solution:

To calculate N, the formula used:

• Number of electrons = number of moles (n) x Avagardo number(Nₐ)
• N = n x Nₐ

Number of moles, n = mass of H₂O (m) / Molecular mass of H₂O(M)

here, M = 2+16 = 18g

Number of moles, n = 18/18

                                 = 1 mol

Applying formula for N:

N = 1 x Nₐ

here, Nₐ = 6.02 x 10²³ molecules/electrons/ions

So, N = 1 x 6.02 x 10²³

         = 6.02 x 10²³ electrons

Hence, the total number of electrons present in 18g of water is 6.02 x 10²³ electrons.