PROBLEMS ON THE MOLE

1. State the mass of each element in:a. 0.5 mol of chromiumb. 1/7 mol of ironc. 1/3 mol carbond. ¼ mol magnesiume. 1/7 mol nitrogen moleculesf. ¼ mol of oxygen molecules

2. Calculate the amount of each element in:a. 46g of sodiumb. 130g zincc. 10g calciumd. 2.4g magnesiume. 13g chromium

3. Find the mass of each element in:a. 0.1 mole leadb. 1/6 mol copperc. 0.1 mol iodine moleculesd. 10 mol hydrogen moleculese. 0.25 mol calciumf. 0.25 mol bromine moleculesg. ¾ mol ironh. 0.20 mol zinci. ½ mol chlorine molecules j. 0.1 mol neon

4. State the amount of substance (mol) in;a. 58.5 g sodium chlorideb. 26.5 g anhydrous sodium carbonatec. 50.0g calcium carbonated. 15.9g copper (II) oxidee. 8.00g sodium hydroxidef. 303g potassium nitrateg. 9.8g sulphuric acidh. 499g copper (II) sulphate-5-water.

5. Given Avogadro’s constant is 6.02 x 1023 mol-1, calculate the number of atoms in: a. 35.5g chlorineb 27g aluminiumc. 3.1g phosphorusd. 336g irone. 48g magnesiumf. 1.6g oxygeng. 0.4g oxygenh. 216g silver

6. How many grams of zinc contain:a. 6 x 1023 atomsb. 6 x 102o atoms?

7. How many grams of aluminium contain:a. 6 x 1023 atomsb. 6 x 102o atoms?

8. How many grams of carbon contain:a. 6 x 1023 atomsb. 6 x 1021 atoms?

9. A compound has the empirical formula CH2O and molar mass 180 g/mol. What is the molecular formula?

10. 0.72g of magnesium combine with 0.28g of nitrogen. What is the formula of magnesium nitride?

11. 1.68g of iron combine with 0.64g of oxygen. What is the formula of the oxide?

12. Calculate the empirical formula of the compound formed when 2.70g of aluminium form 5.10g of its oxide?

13. Barium chloride forms a hydrate with contains 85.25% barium chloride and 14.75% water crystallisation. What is the formula of this hydrate?

14. What is the volume of oxygen needed for the complete combustion of 2dm3 of propane?

15. 0.5 mol of Na2CO3will neutralise a. 1dm3 of HCl(aq) of concentration 1mol/dm3.

TRUE OR FALSE? b. 1dm3 of H2SO4(aq) 1 mol/dm3

c. 500 cm3 of HCl(aq) 1M d. 250 cm3 of HNO3 2M e. 200 cm3 of H2SO4(aq) of 2.5 M f. 500 cm3 of HNO3(aq) 2 M

16. Vinegar is a solution of ethanoic acid. A 10.0 cm3

portion of a certain brand of vinegar needed 55cm3 of 0.200 mol/dm3 NaOH(aq) solution to neutralise the ethanoic acid in it. Calculate the concentration of ethanoic acid in the vinegar in mol.dm-3.

17. The table gives the formula and relative molecular masses of some gases

FORMULA Ne C2H2 O2 Ar NO2 SO2 SO3

Mr 20 26 32 40 46 64 80V (cm3) occupiedBy 1g of gas at stp 1120 861 700 560 485 350 280

a. Plot a graph of volume (Y-axis) against Mr (X-axis)b. Use the graph to predict the volumes occupied at stp by 1g of F2 and 1g of Cl2.c. What is the relative molecular mass of a gas which occupies 508cm3 per gram at stp? If the gas contains only

carbon and oxygen, what is its formula?