CBSE Class 11-science Answered

Molar mass of PO₄^3- = 95 g / mole

PO₄^3- means atom has gained 3 electrons. We will first calculate the mass of these 3-electrons.

Gained mass = 3 x 9.1091x10^-28 (mass of electron) x 6.022x10²³ (Avogadro's constant) = 0.00164565 g / mole.

Molar mass of PO₄^3- = 95 g / mole

19 g of PO₄^3- means = 19 / 95 moles = 0.2 moles.

Ions in 0.2 moles = 0.2 x 6.022 x 10²³ = 1.2044 x 10²³ ions.

Charge on each ion = 3 x 1.602 x 10^-19 = 4.806 x 10^-19 coulombs.

So, charge of 19g of PO₄^3-ions = 1.2044 x 10²³ x 4.806 x 10^-19 coulombs = 5.78 x 10⁴ Coulombs.