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: Option 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