multiple choice chem question

Question

Which is more concentrated in terms of molarity, 5485 mg of manganese(III) carbonate dissolved in 14 mL of water, or 0.85 kg of lithium nitrite dissolved in 3.2 L of water?

A. manganese(III) carbonate solution

B. lithium nitrite solution

C. the concentrations are equal

Answer 1

Molar mass of Mn₂(CO₃)₃ = (54.9 * 2) + (3 * (12 + (16 * 3))) = 289.8 g/mol

Number of moles of Mn₂(CO₃)₃ = 5485 mg * 1g/1000mg * 1mol/289.8g = 0.0189 mol

Volume of Mn₂(CO₃)₃ = 14 mL * 1L/1000mL = 0.014L

Concentration of Mn₂(CO₃)₃ = 0.0189mol/0.014L = 1.35M

Molar mass of LiNO₃ = 6.9 + 14 + (16 * 3) = 68.9 g/mol

Number of moles of LiNO₃ = 0.85 kg * 1000g/1kg * 1mol/68.9g = 12.34 mol

Concentration of LiNO₃ = 12.34 mol/3.2 L = 3.86M

Concentration of LiNO₃ is higher.