Can you me with this molarity problem?

Question

What volume of NaOH is needed to make 50mL of a 1M solution?

Answer 1

Are you asking the right question here?  What you really need to find is the MASS (m) of NaOH required to make 50 mL at a concentration of 1 M.

 

Find the molecular weight (W) of NaOH.

 

Na = 22.99

O = 16.00

H = 1.01

 

W = sum = 40.00 g/mol

 

Find number of moles (n) that you need for 50 mL at 1 mol/L.

 

1 mol / (1000 mL) = n / (50 mL)

 

n = [(50 mL)/(1000 mL)] (1 mol) = 0.05 mols

 

But n also equals

 

n = m/W ⇒

 

m = nW = (0.05 mols)(40.00 g/mol) = 2.00 g

 

You need 2.00 g of NaOH to make 50 mL of a solution at 1 M.