Question 7.ex.1: Calculate the molarity of a solution made from 20.0 g of NaO...

Identify the known quantities and the desired quantity.

20.0 g NaOH
250 mL solution                        ? M (mol/L)
known quantities                            desired quantity

Step [2] Convert the number of grams of solute to the number of moles. Convert the volume of the solution to liters, if necessary.
• Use the molar mass to convert grams of NaOH to moles of NaOH (molar mass 40.0 g/mol).

• Convert milliliters of solution to liters of solution using a mL–L conversion factor.

Step [3] Divide the number of moles of solute by the number of liters of solution to obtain the molarity.

$M =\frac {moles  of  solute  (mol)}{V (L)}=\frac {0.500  mol  NaOH}{0.25 L  solution}= 2.0 M$