Question

How many mL of 12% NaOH solution contains 8.5 g of NaOH?

Answer 1

12%(m/v) means that there will be 12 grams of NaOH in 100 mL of the solution. 12 g NaOH /100 mL solution.

Molarity is in moles per liter so convert the grams of NaOH to moles of NaOH and convert 100 mL to liters then divide the number of moles of NaOH by the number of liter of solution.

12 g NaOH x 1.00 mol NaOH /40.0 g NaOH=0.3 mol NaOH

100 mL=0.100 L

0.3 mol NaOH/0.100 mol NaOH=3.00 M NaOH

Thus the molarity of NaOH IS 3.00 M.

Number of moles = 8.5 g NaOH x 1.00 mol NaOH /40.0 g NaOH=0.2125 mol NaOH

Molarity = moles / volume

Volume = moles / Molarity

Volume in L = 0.2125 mole / 3.00 mol/L

Volume in L =0.071 L

Volume in L = 71 mL

Or we can use as follows:

12 g/100 ml = 8.5 g/x

X= 71 mL