Preparing Solutions: Dilutions
Example 1:
For a certain experiment a chemist needs to prepare a 55 ml sample of
1.85M hydrochloric acid. The stock solution of HCl is 12.0M. What
volume of acid does the chemist need to start with?
Dilution Equation: M1V1 = M2V2
or C1V1 = C2V2
Remember: the number of moles in the first situation is equal to the
number of moles in the second situation.
n1 = n2
n= MV
therefore,
Solution:
Given: M1 = 12.0M
V1 = ?
M1V1 = M2V2
(12.0M) x (V1) = (1.85M) x (55 ml)
V1 = (1.85M) x (55ml)
12.0M
M2 = 1.85 M
V2 = 55 ml
V1 = 8.48 ml of HCl
Therefore the chemist will need to pour out 8.48 ml of HCl from the
stock bottle. How much water will the chemist need to add to the
8.48ml to make the new 55ml solution?