Answer to Question #112037 in Chemistry for Joy

Question

1. Determine the molarity of a solution containing 10.6g of sodium carbonate dissolve in
a)250cm³ of distilled water
b)500cm³ of distilled water

Answer 1

Solution:

Molarity or molar concentration is the number of moles of solute per liter of solution, which can be calculated using the following equation:

Molarity = mol solute / L of solution.

Molar mass of sodium carbonate = M_r(Na₂CO₃) = 105.9888 g/mol = 106 g/mol.

To find molaruty of Na₂CO₃ we need to find out how many moles of sodium carbonate are in solution. We can convert the mass of the solute to moles using the molar mass of sodium carbonate (Na₂CO₃), 106 g/mol:

Moles of Na₂CO₃ = Mass of Na₂CO₃ / Molar mass of Na₂CO₃

Moles of Na₂CO₃ = n(Na₂CO₃) = (10.6 g) / (106 g/mol) = 0.1 mol.

a) V(solution) = 250 cm³ = 0.25 L.

Molarity of Na₂CO₃ = n(Na2CO3) / V = (0.1 mol) / (0.25 L) = 0.4 M.

Molarity of Na₂CO₃ is 0.40 M.

Answer (a): Molarity of Na₂CO₃ is 0.40 M.

b) V(solution) = 500 cm³ = 0.50 L.

Molarity of Na₂CO₃ = n(Na₂CO₃) / V = (0.1 mol) / (0.50 L) = 0.20 M.

Molarity of Na₂CO₃ is 0.20 M.

Answer (b): Molarity of Na₂CO₃ is 0.20 M.