Question

Question #91c2b

Answer 1

`19.0 mL`

Explanation:

First, find the moles of NaOH(aq) needed to create the 100.0 mL of 0.020 M NaOH(aq) solution.

`mols NaOH(aq) = Molarity * Liters`

`mols NaOH(aq) = 0.020 M * 0.1000L`

`mols NaOH(aq) = 0.002 mols`

Now that you know how many moles you need, find many mL of 0.105 M NaOH(aq) solution is needed in order to have 0.002 moles.

`"Liters" = "moles NaOH(aq)"/"Molarity"`

`"Liters" = "0.002 moles NaOH(aq)"/"0.105 M NaOH(aq)"`

`"Liters" = 0.0190476`

Since you have 3 significant figures the answer would be `0.0190 L`, or:

`19.0 mL`