Question

What is the molarity of pure acetic acid? Assume density of acetic acid = 1 g/ml and Molecular Weight = 60 g/mol.

• A. 12.7
• B. 16.7
• C. 20.7
• D. 55.5

Hint:

For pure liquids, Molarity = (Density $\times$ 1000) Molar Mass.

Answer 1

The Correct Option is B

Step 1: Concept
Molarity ($M$) is defined as the number of moles of solute per liter of solution.

Step 2: Meaning
Density = 1 g/ml means 1000 g of acetic acid exists in 1000 ml (1 Liter) of volume.

Step 3: Analysis
Number of moles = Mass Molar Mass = $1000 \text{ g} / 60 \text{ g/mol} = 16.666...$ moles. Since this is in 1 Liter, $M = 16.7$.

Step 4: Conclusion
The molarity of pure acetic acid under these conditions is 16.7 M. Final Answer: (B)