Question

How many mol of NaOH are in 0.55 mL of 25%w/v NaOH solution? (Report your answer to 2 sig figs.)

Answer 1

volume of NaOH = 0.55 mL

w/v % = 25%

molecular weight of NaOH = 40 g/mol

25% w/v = 25g/100 ml

               = 0.25 g/ml

               = 250 g/L

to convert g/L to mol/L

molarity = 250 / 40

              = 6.25 M

molarity = moles / volume

6.25 = moles / (5.5 x 10^-4)L

moles = 3.4 x 10^-3

moles of NaOH = 3.4 x 10^-3