Chemistry step by step

Question

What is the molarity of a solution in which 0.45 grams of sodium nitrate are dissolved in 265 mL of solution?

Answer 1

What is the definition of molarity?

It is moles of solute (sodium nitrate) per liter of solution.

We are given the ml of solution, so we can easily convert to liters (L).

265 ml x 1 L / 1000 ml = 0.265 L

We are given the mass (grams) of sodium nitrate (NaNO₃), so we can find the moles

molar mass NaNO₃ = 84.99 g / mol

moles NaNO₃ = 0.45 g x 1 mol / 84.99 g = 0.00529 moles

We now have all the info needed to calculate molarity, i.e. moles and liters.

Molarity = 0.00529 moles / 0.265 L

Molarity = 0.01998 M = 0.020 M (2 sig. figs.)