Question

A standard solution of sodium carbonate was prepared by dissolving 10.6 g of the anhydrous salt in distilled water. The solution was then transferred to a standard flask and the total volume was adjusted to the 500 mL mark.Calculate the concentration of the sodium carbonate solution in mol/L.

Answer 1

The concentration of the solution is 0.2 mol/L

Step-by-step explanation

Given that;

The mass of sodium carbonate dissolved is 10.6 grams

The volume of the flask is 500mL

Follow the steps below to find the concentration of the solution

Step 1; Find the number of moles of the solute using the below formula

`\text{ mole = }\frac{\text{ mass}}{\text{ molar mass}}`

Recall, the molar mass of sodium carbonate is 106 g/mol

`\begin{gathered} \text{ mole = }\frac{\text{ 10.6}}{\text{ 106}} \\ \text{ mole = 0.1 moles} \end{gathered}`

The moles of sodium carbonate is 0.1 moles

Step 2; Convert the volume to liters

Let x represents the volume of the flask in liters

`\begin{gathered} \text{ 1mL }\rightarrow\text{ 0.001L} \\ \text{ 500mL }\rightarrow\text{ xL} \\ \text{ cross multiply} \\ \text{ 1mL }*\text{ xL = 0.001L }*\text{ 500mL} \\ \text{ Isolate xL} \\ \text{ xL = }\frac{\text{ 0.001L }*500\cancel{mL}}{1\cancel{mL}} \\ \text{ xL = 0.001}*\text{ 500} \\ \text{ xL = 0.5L} \end{gathered}`

The volume of the flask is 0.5L

Step 3; Find the concentration of the solution

`\begin{gathered} \text{ Concentration = }\frac{\text{ 0.1}}{\text{ 0.5}} \\ \text{ concentration = 0.2 mol/L} \end{gathered}`

Therefore, the concentration of the solution is 0.2 mol/L