Question

How many total moles of ions are released when the following sample dissolves completely in water? 6.188 x 10 21 formula units of NiCl 2 a. 1.36 mol of ions b. 1.86 mol of ions c. 3.08 x 1022 mol of ions d. 0.0205 mol of ions e. 3.08 x 10-2 mol of ions

Answer 1

Answer:

e. 3.08 x 10⁻² mol of ions.

Explanation:

• Every 1.0 mole of any compound contains Avogadro's number of molecules (6.022 x 10²³).

• We can get the no. of moles of NiCl₂ using cross multiplication:

1.0 mol NiCl₂ contains → 6.022 x 10²³ molecules.

??? mol NiCl₂ contains → 6.188 x 10²¹ molecules.

∴ The no. of moles of NiCl₂ = (1.0 mol)(6.188 x 10²¹ molecules)/(6.022 x 10²³ molecules) = 1.028 x 10⁻² mol.

• NiCl₂ is ionized according to the equation:

NiCl₂ → Ni²⁺ + 2Cl⁻.

Which means that every 1.0 mol of NiCl₂ is ionized to produce 3.0 moles (1.0 mol of Ni²⁺ and 2 moles of Cl⁻).

∴ The total moles of ions are released = 3 x 1.028 x 10⁻² mol = 3.083 x 10⁻² mol of ions.