List of practice Questions

Calculate the molar mass of the following: 
(i) \(\text{H}_2\text{O}\) (ii) \(\text{CO}_2\) (iii) \(\text{CH}_4\)
Calculate the mass of sodium acetate \((\text{CH}_3\text{COONa})\) required to make 500 mL of 0.375 molar aqueous solution. Molar mass of sodium acetate is \(82.0245\, \text{g mol}^{–1}.\)
What will be the mass of one \(^{12}C\) atom in g?
Use the data given in the following table to calculate the molar mass of naturally occuring argon isotopes:
IsotopeIsotopic molar massAbundance
36Ar35.96755 g mol–1 0.337% 
38Ar37.96272 g mol–1 0.063%
40Ar 39.9624 g mol–1 99.600% 
In a reaction \(A + B_2 → AB_2\) Identify the limiting reagent, if any, in the following reaction mixtures.
  1. 300 atoms of A + 200 molecules of B
  2. 2 mol A + 3 mol B
  3. 100 atoms of A + 100 molecules of B
  4. 5 mol A + 2.5 mol B
  5. 2.5 mol A + 5 mol B
A sample of drinking water was found to be severely contaminated with chloroform, CHCl3, supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass).
  1. Express this in per cent by mass.
  2. Determine the molality of chloroform in the water sample.
What is the concentration of sugar (C12H22O11) in mol L–1 if its 20 g are dissolved in enough water to make a final volume up to 2L?
Determine the molecular formula of an oxide of iron, in which the mass per cent of iron and oxygen are 69.9 and 30.1, respectively.