14.8 g of a salt (z)dissolved in 250 cm3 of distilled water gives a concentration of 0.80 mol dm-3. Calculate the molar mass of the salt (z).
A. 13.5 g mol-1 B. 18.5 g mol-1 C. 47.4 g mol-1 D. 74.0 g mol-1
Correct Answer: D
Explanation
250cm3 of distilled water contains 14.8g of salt(z) 1cm3 of distilled water will contain \(\frac{14.8 x 1}{250}\) of salt (z) :. 1000cm3 of distilled water will contain \(\frac{14.8 x 1 x 1000}{250}\) = 59.2g/dm3of salt (z) Concentration in mol/dm3 = \(\frac{concentration in g/dm3}{molar mass} 0.80 = \(\frac{59.2}{molar mass}\) molar mass = \(\frac{59.2}{0.80}\) = 74.0 g/mol
