Question

A technologist is creating a solution that contains 25.5 grams of NaOH that is dissolved in 1 L of laboratory grade water. What is the molarity of the solution that the technologist created

Answer 1

0.638 M NaOH

Step-by-step explanation:

To find the molarity of the solution, you need to (1) convert grams NaOH to moles NaOH (via the molar mass of NaOH) and then (2) calculate the molarity (via the molarity formula). It is important to arrange the conversions/ratios in a way that allows for the cancellation of units (the desired unit should be in the numerator).

(Step 1)

Molar Mass (NaOH): 22.990 g/mol + 15.998 g/mol + 1.008 g/mol

Molar Mass (NaOH): 39.996 g/mol

25.5 grams NaOH 1 mole
----------------------------- x ---------------------------- = 0.638 moles NaOH
39.996 grams

(Step 2)

Molarity = moles / volume (L)

Molarity = 0.638 moles / 1 L

Molarity = 0.638 M