Question

A solution is made by dissolving 23.2g of Chromium (II) nitrate, CR(NO3)2, in enough water to make 250. ml of solution. Calculate the molartity of each species:

Cr(NO3)2= mol/L

Cr^2+= mol/L

NO3- = mol/L

Answer 1

Mass of Chromium (II) nitrate = 23.2 g

Molar mass of chromium (II) nitrate = 176.0059 g / mol

Moles of chromium (II) nitrate = ( Mass / Molar mass) = ( 23.2 g / 176.0059 g / mol ) = 0.13 mol

Volume of the solution = 250 mL = 0.25 L

Molarity of Cr(NO₃)₂ = ( Moles / Volume ) = ( 0.13 / 0.25 ) mol / L = 0.52 mol / L

Cr(NO₃)₂    -------> Cr²⁺ + 2NO₃^-

Therefore, Molarity of Cr²⁺ = 0.52 mol / L

Molarity of NO3^- = ( 2 x 0.52 ) mol / L = 1.04 mol / L