Question

How many Mg ions are present in 3.00 moles of MgCl2?

Answer 1

Task:

How many Mg ions are present in 3.00 moles of MgCl₂?

Solution:

In water MgCl₂ dissociates to ions: a cation of magnesium (Mg²⁺) and two anions of cloride (Cl^-).

MgCl₂ = Mg²⁺ + 2Cl^-

Hence, n(MgCl₂) = n(Mg²⁺) = 3.00 moles (according to the reaction equation).

n = N / N_a, where N_a - Avogadro's number = 6.022*10²³ mol^-1.

Then,

N(Mg²⁺) = n(Mg²⁺) * N_a = 3.00 * 6.022*10²³ = 18.066*10²³ = 1.81*10²⁴

Answer: 1.81*10²⁴ Mg²⁺ ions are present in 3.00 moles of MgCl₂.