Question

What is the molarity of 5.30 g of Na2CO3 dissolved in 400.0 mL solution?

(a) 0.150 M

(b) 0.125 M

(c) 0.155 M

(d) 0.120 M

The question was asked in an interview for internship.

This intriguing question comes from Yields in Cell Culture in chapter Homogenous Reactions of Bioprocess Engineering

Answer 1

The correct option is (b) 0.125 M

Explanation: MV = grams / molar mass

(x) (0.4000 L) = 5.30 g / 105.988 g mol^-1

0.12501415 M

x = 0.125 M (to three sig figs).