Answer to Question #337120 in Chemistry for ash

Question

An aqueous solution is made by dissolving 29.4 grams of nickel(II) nitrate in 403 grams of water.  

The molality of nickel(II) nitrate in the solution is m

Answer 1

Solution:

nickel(II) nitrate = Ni(NO₃)₂

The molar mass of Ni(NO₃)₂ is 182.703 g/mol

Therefore,

Moles of Ni(NO₃)₂ = [29.4 g Ni(NO₃)₂] × [1 mol Ni(NO₃)₂ / 182.703 g Ni(NO₃)₂] = 0.1609 mol Ni(NO₃)₂

Kilograms of water = (403 g) × (1 kg / 1000 g) = 0.403 kg

Molality = Moles of solute / Kilograms of solvent

Therefore,

Molality of Ni(NO₃)₂ solution = (0.1609 mol) / (0.403 kg) = 0.399 mol/kg = 0.4 m

Molality of Ni(NO₃)₂ solution = 0.4 m

Answer: The molality of nickel(II) nitrate in the solution is 0.4 m