1. moles of solute = molarity x volume
QUESTION:
How much 6.00 M NaOH would you need to dilute to make 8.00 x 102 mL of a M solution?
A mL B mL C mL D x 102 mL
In a dilution we are adding solvent; the amount of solute remains the same.
How do we determine the amount of solute?
moles of solute = molarity x volume
Number of moles remains the same so:
MiVi = MfVf
SCRIPT FOR SLIDE 1
How much six point zero zero molar sodium hydroxide would you need to dilute to make 8 point zero zero times ten to the second milliliters of a point five zero zero molar solution? A, 15.0 milliliters; B, 66.7 milliliters; C, 96.0 mililiters; or D, 2.40 times ten to the second milliliters?
CLICK
The principle we need to remember with dilution problems is that we are adding solvent only; the amount of solute remains the same.
How do we determine the amount of solute?
The number of moles of solute equals the molarity of the solution times its volume.
Since the number of moles remains the same
The initial molarity times volume equals the final molarity times volume.

2. Putting in the numbers:
Solving for Vi, we get:
Putting in the numbers:
How much 6.00 M NaOH would you need to dilute to make 8.00 x 102 mL of a M solution?
A mL B mL C mL D x 102 mL
SCRIPT FOR SLIDE 2
Solving for the initial volume, we get
CLICK
v i equals m f v f over m i.
Putting in the numbers gives us
v i equals eight point zero zero times ten to the second millliters times point five zero zero molar over six point zero zero molar.
Molarity cancels,
leaving millilliters as our unit and we get
Sixty-six point seven milliliters
So the correct answer is B.

3. Video ID: 5-16-JJW © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Jeremy Wessel Narrator: Cynthia Lamberty Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08