You've been asked to make a solution of sodium hydroxide with a concentration of 1.5 molarity and a volunteer of 150ml. How many grams of sodium hydroxide do you need?

To calculate mass in g we first need moles of NaOH for this preparation. For this purpose we use the formula

Molarity = no. of moles / solution in liter

Here we have

Molarity = 1.5M

Solution = 150ml

Convert it into liter we get

150/1000 = 0.15L

Putting in

No. of moles = molarity x solution in liter

= 1.5 x 0.15 = 0.225mole of NaOH

Now we can use these moles to calculate mass in gram by formula

No. of moles = mass in gram/molar mass

Molar mass of NaOH is 39.997g/mol

Now use

Mass in gram = no. of mole x molar mass of NaOH

= 0.225 x 39.997

= 8.999g = 9g

So

9g of NaOH is required to make 150ml of 1.5M solution.