HKDSE (Hong Kong) · Chemistry

Mole Calculations

55 practice questions, each with the answer and an explanation.

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All 55 questions

  1. Find the relative formula mass of Mg(OH). (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  2. Find the relative formula mass of Al(SO). (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  3. Find the relative formula mass of HNO. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  4. Find the relative formula mass of AlO. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  5. Find the relative formula mass of HSO. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  6. Find the relative formula mass of (NH)SO. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  7. Find the relative formula mass of FeO. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  8. Find the relative formula mass of NHCl. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  9. Find the relative formula mass of NaCO. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  10. Find the relative formula mass of CHOH. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  11. Find the relative formula mass of CHO. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  12. Find the relative formula mass of MgSO. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  13. Find the relative formula mass of Zn(NO). (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  14. Find the relative formula mass of KSO. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 63.5, Zn = 65, Ag = 108)
  15. What is the mass of 3 mol of NaCl? (Relative formula mass = 58.5)
  16. How many moles are present in 174 g of Mg(OH)? (Relative formula mass = 58)
  17. How many moles are present in 11.7 g of NaCl? (Relative formula mass = 58.5)
  18. What is the mass of 3 mol of HSO? (Relative formula mass = 98)
  19. What is the mass of 2 mol of CaCO? (Relative formula mass = 100)
  20. How many moles are present in 50 g of CaCO? (Relative formula mass = 100)
  21. What is the mass of 0.25 mol of NaOH? (Relative formula mass = 40)
  22. How many moles are present in 21.2 g of NaCO? (Relative formula mass = 106)
  23. Calculate the percentage by mass of O in MgSO. (H = 1, C = 12, N = 14, O = 16, Mg = 24, S = 32, Cl = 35.5, Al = 27, Ca = 40, Fe = 56, Cu = 63.5, Na = 23)
  24. Calculate the percentage by mass of O in CuSO. (H = 1, C = 12, N = 14, O = 16, Mg = 24, S = 32, Cl = 35.5, Al = 27, Ca = 40, Fe = 56, Cu = 63.5, Na = 23)
  25. Calculate the percentage by mass of H in (NH)SO. (H = 1, C = 12, N = 14, O = 16, Mg = 24, S = 32, Cl = 35.5, Al = 27, Ca = 40, Fe = 56, Cu = 63.5, Na = 23)
  26. Calculate the percentage by mass of O in FeO. (H = 1, C = 12, N = 14, O = 16, Mg = 24, S = 32, Cl = 35.5, Al = 27, Ca = 40, Fe = 56, Cu = 63.5, Na = 23)
  27. Calculate the percentage by mass of Fe in FeO. (H = 1, C = 12, N = 14, O = 16, Mg = 24, S = 32, Cl = 35.5, Al = 27, Ca = 40, Fe = 56, Cu = 63.5, Na = 23)
  28. Calculate the percentage by mass of Al in AlO. (H = 1, C = 12, N = 14, O = 16, Mg = 24, S = 32, Cl = 35.5, Al = 27, Ca = 40, Fe = 56, Cu = 63.5, Na = 23)
  29. Calculate the percentage by mass of O in AlO. (H = 1, C = 12, N = 14, O = 16, Mg = 24, S = 32, Cl = 35.5, Al = 27, Ca = 40, Fe = 56, Cu = 63.5, Na = 23)
  30. Calculate the percentage by mass of H in NH. (H = 1, C = 12, N = 14, O = 16, Mg = 24, S = 32, Cl = 35.5, Al = 27, Ca = 40, Fe = 56, Cu = 63.5, Na = 23)
  31. 10 cm of 6 mol/dm hydrochloric acid is diluted with water to a total volume of 200 cm. What is the new concentration?
  32. 25 cm of 1 mol/dm hydrochloric acid is diluted with water to a total volume of 1000 cm. What is the new concentration?
  33. 50 cm of 1 mol/dm hydrochloric acid is diluted with water to a total volume of 200 cm. What is the new concentration?
  34. 10 cm of 2 mol/dm hydrochloric acid is diluted with water to a total volume of 100 cm. What is the new concentration?
  35. 10 cm of 0.5 mol/dm hydrochloric acid is diluted with water to a total volume of 250 cm. What is the new concentration?
  36. 10 cm of 4 mol/dm hydrochloric acid is diluted with water to a total volume of 250 cm. What is the new concentration?
  37. What is the volume of 0.5 mol of any gas at room temperature and pressure? (Molar volume = 24 dm/mol at r.t.p.)
  38. What is the volume of 0.1 mol of any gas at room temperature and pressure? (Molar volume = 24 dm/mol at r.t.p.)
  39. What is the volume of 0.25 mol of any gas at room temperature and pressure? (Molar volume = 24 dm/mol at r.t.p.)
  40. What is the volume of 3 mol of any gas at room temperature and pressure? (Molar volume = 24 dm/mol at r.t.p.)
  41. What is the volume of 2 mol of any gas at room temperature and pressure? (Molar volume = 24 dm/mol at r.t.p.)
  42. 200 g of calcium carbonate reacts completely according to CaCO → CaO + CO. What mass of calcium oxide is formed? (Relative masses: calcium carbonate 100, calcium oxide 56.)
  43. 20 g of calcium carbonate reacts completely according to CaCO → CaO + CO. What mass of calcium oxide is formed? (Relative masses: calcium carbonate 100, calcium oxide 56.)
  44. 6 g of magnesium reacts completely according to 2Mg + O → 2MgO. What mass of magnesium oxide is formed? (Relative masses: magnesium 24, magnesium oxide 40.)
  45. 50 g of calcium carbonate reacts completely according to CaCO → CaO + CO. What mass of calcium oxide is formed? (Relative masses: calcium carbonate 100, calcium oxide 56.)
  46. 10 g of calcium carbonate reacts completely according to CaCO → CaO + CO. What mass of calcium oxide is formed? (Relative masses: calcium carbonate 100, calcium oxide 56.)
  47. 100 g of calcium carbonate reacts completely according to CaCO → CaO + CO. What mass of calcium oxide is formed? (Relative masses: calcium carbonate 100, calcium oxide 56.)
  48. 12 g of magnesium reacts completely according to 2Mg + O → 2MgO. What mass of magnesium oxide is formed? (Relative masses: magnesium 24, magnesium oxide 40.)
  49. 25 g of calcium carbonate reacts completely according to CaCO → CaO + CO. What mass of calcium oxide is formed? (Relative masses: calcium carbonate 100, calcium oxide 56.)
  50. A compound contains 80 g of Ca and 142 g of Cl. What is its empirical formula? (Ca = 40, Cl = 35.5)
  51. A compound contains 46 g of Na and 32 g of S. What is its empirical formula? (Na = 23, S = 32)
  52. A compound contains 92 g of Na and 64 g of S. What is its empirical formula? (Na = 23, S = 32)
  53. A compound contains 112 g of Fe and 48 g of O. What is its empirical formula? (Fe = 56, O = 16)
  54. A compound contains 12 g of C and 2 g of H. What is its empirical formula? (C = 12, H = 1)
  55. A compound contains 48 g of C and 8 g of H. What is its empirical formula? (C = 12, H = 1)

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