Question

A liter of water was found to contain 10 mg of benzene (C6H6). What is the concentration of benzene in mg/L, ppm, and molarity?

Answer 1

Answer:

10 mg/L:  C₆H₆

10 ppm: C₆H₆

1.28×10⁻⁴ M : [C₆H₆]

Explanation:

A liter of water was found to contain 10 mg of benzene (C6H6).

This can be understood as mg/L concentration. 10 mg of benzene are contained in 1L of solution.

If we want to write concentration of ppm, we assume μg/mL

So let's convert 10 mg to μg

10 mg . 1000 = 10000 μg

and 1L = 1000 mL

So μg/mL → 10000 μg / 1000 mL  = 10

Molarity is mol/L

We know that the volume is 1L so let's convert the 10 mg of benzene to moles. (mass (g) / molar mass)

0.01 g / 78 g/mol = 1.28×10⁻⁴ moles