Question

A solution is made by dissolving 12.8 g of sodium carbonate (Na₂CO₃) in enough water to make 325 mL of solution. The concentration of sodium carbonate in the solution is:

A. 0.121 M
B. 0.372 M
C. 0.0393 M
D. 3.25 M
E. 12.8 M

Answer 1

To find the concentration of sodium carbonate in the solution, divide the number of moles of sodium carbonate (0.1208 moles) by the volume of the solution in liters (0.325 liters), resulting in a concentration of 0.372 M, which corresponds to answer B.

Step-by-step explanation:

The concentration of sodium carbonate in the solution is calculated by first finding the number of moles of sodium carbonate, and then dividing by the volume of the solution in liters. Using the molar mass of sodium carbonate (Na2CO3), which is approximately 105.99 g/mol, we calculate the moles:

Moles of sodium carbonate = Mass / Molar mass = 12.8 g / 105.99 g/mol = 0.1208 moles (approximately).

Now, we convert the volume of the solution to liters:

325 mL = 0.325 liters.

The concentration in molarity (M) is calculated as:

Concentration (M) = Moles of solute / Volume of solution in liters = 0.1208 moles / 0.325 liters = 0.372 M.

Therefore, the correct answer is B. 0.372 M.