MCAT Chemistry Question — Dilution Equation
- Nov 07, 2014
- MCAT Blog, MCAT Chemistry, MCAT Question of the Day
- Reviewed By: Liz Flagge
A student prepares a ten liter solution of 0.01M NaOH by starting with 25mL of a stock solution. What is the concentration of the stock solution?
A) 0.1 M
B) 0.4 M
C) 2.5 M
D) 4.0 M
The student is only adding water when doing the dilution. Thus moles i = moles f. Because M = mol / volume, you can substitute M x V for moles. Thus the dilution equation is:
M1V1 = M2V2
Plugging in the values given, we get:
(0.01M)(10L) = (0.025L) x M2
0.1 moles = 0.025 L x M2
0.1 / 0.025 = M2
100 / 25 = M2
4 = M2
Therefore, (D) is the answer.
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