Return to Blog Homepage

MCAT Chemistry Question — Dilution Equation

  • by John
  • Nov 07, 2014
  • MCAT Blog, MCAT Chemistry, MCAT Question of the Day

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

 

 

Explanation

 

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.

 

Want more MCAT practice?

We’ve got options for every schedule and learning style!

From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative full-length practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!

Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT Advisor using the form below. No obligation, just expert advice.

Schedule My Free Consultation

Submit a Comment