A 1.5 M solution of NaOH was made in a laboratory. If the solution made had a volume of 4.5 L, how many grams of NaOH were added?

270g

Explanation:

Given parameters:

Concentration of NaOH  = 1.5M

Volume  = 4.5L

Unknown

Mass of NaOH added  = ?

Solution:

To solve the problem, we need to find the number of moles of the NaOH first;

 Number of moles  = concentration x volume

 Number of moles  = 1.5 x 4.5  = 6.75mol  

Now;

  Mass  = Number of moles x molar mass

 Molar mass of NaOH  = 23 + 16 + 1  = 40g/mol

  Mass  = 6.75 x 40  = 270g