Question

If 100 mL of water contains 5 grams of NaCl, m.w. 58.5 daltons, what is the molarity of the solution in moles/L?

Answer 1

To find the molarity, divide 5 grams of NaCl by its molar mass (58.44 g/mol) to get the number of moles, and then divide by the volume in liters (0.1 L). The solution's molarity is 0.855 M.

Step-by-step explanation:

To calculate the molarity of a solution where 5 grams of NaCl is dissolved in 100 mL of water, we need to convert grams to moles and milliliters to liters. Since the molar mass of NaCl is 58.44 g/mol, we divide the mass of NaCl by its molar mass to find the number of moles.

Here is the calculation:

Number of moles of NaCl = 5 g ÷ 58.44 g/mol = 0.0855 mol.

Now, to find molarity, we divide the moles of solute by the volume of solution in liters.

Molarity (M) = Number of moles of NaCl ÷ Volume of solution in liters = 0.0855 mol ÷ 0.1 L = 0.855 M.

Therefore, the solution's molarity is 0.855 M.