A 205-mL sample of ocean water contains 6.8 g of NaCl. What is the molarity of the solution with respect to NaCl?

Solution 63P :

Step 1:

Given :

Amount of solute - NaCl = 6.8 g

Amount of solvent -ocean water = 205-mL

Molarity of the solution with respect to NaCl = ?

Molarity(M) is a unit of concentration measuring the number of moles of a solute per liter of solution. The SI unit of molarity is mol/L.

Formula to find the molarity of solution :

Molarity =

Amount of solvent is given in mL, let’s convert to L :

1 L = 1000 mL

Therefore, 205 mL in L will be :

= 0.205 L

We have the amount of solute in g, let’s calculate the number of moles first :

Number of moles (n) =

Molar mass of NaCl = 58.44 g/mol.

Therefore, n =

= 0.116 moles.