Question

if I add water to 170 mL of a 0.40 M KOH solution until the final volume is 375 mL, what will the molarity M of the diluted solution be?

Answer 1

4.7 M It may be wrong, but I hope it helps!

Explanation:

When you're diluting a solution, you're essentially keeping the number of moles of solute constant while changing the total volume of the solution.

Now, let's assume that you don't know the equation for dilution calculations.

In this case, you can use the molarity and volume of the concentrated solution to determine how many moles of hydrochloric acid you start with.

c

=

n

V

⇒

n

=

c

⋅

V

n

HCl

=

18 M

⋅

190

⋅

10

−

3

L

=

3.42 moles HCl

You then add water to get the total volume of the solution from  

190 mL

to  

730 mL

.

The number of moles of hydrochloric acid remains unchanged, which means that the molarity of the diluted solution will be

c

=

3.42 moles

730

⋅

10

−

3

L

=

4.7 M