1. Stochiometric Relationships

1.What amount of oxygen, O2, (in moles) contains 1.8×1022 molecules?

2. Which compound has the empirical formula with the greatest mass?

3. __C2H2(g) + __O2(g) → __ CO2(g) + __ H2O(g) When the equation above is balanced, what is the coefficient for oxygen?  

4. 3.0 dm3 of sulfur dioxide is reacted with 2.0 dm3 of oxygen according to the equation below. 2SO2(g) + O2(g) → 2SO3(g) What volume of sulfur trioxide (in dm3) is formed? (Assume the reaction goes to completion and all gases are measured at the same temperature and pressure.)

5. What will happen to the volume of a fixed mass of gas when its pressure and temperature (in Kelvin) are both doubled?

6. What amount (in moles) is present in 2.0 g of sodium hydroxide, NaOH?

7. A hydrocarbon contains 90% by mass of carbon. What is its empirical formula?

8. Copper can react with nitric acid as follows. 3Cu +_HNO3 → _Cu(NO3)2 +_H2O + _NO What is the coefficient for HNO3 when the equation is balanced?

9. Lithium hydroxide reacts with carbon dioxide as follows. 2LiOH + CO2 → Li2 CO3 + H2O What mass (in grams) of lithium hydroxide is needed to react with 11 g of carbon dioxide?

10. Which change in conditions would increase the volume of a fixed mass of gas?

	Pressure /kPa	Temperature /K
A.	Doubled	Doubled
B.	Halved	Halved
C.	Doubled	Halved
D.	Halved	Doubled

11. How many hydrogen atoms are contained in one mole of ethanol, C2H5OH?

12. The percentage by mass of the elements in a compound is C = 72%,    H = 12%,    O = 16%. What is the mole ratio of C:H in the empirical formula of this compound?

13. What is the coefficient for O2(g) when the equation below is balanced? __C3H8(g) + __O2(g) → __CO2(g) + __H2O(g)

14. What amount of NaCl (in moles) is required to prepare 250 cm3 of a 0.200 mol dm–3 solution?

15. For which set of conditions does a fixed mass of an ideal gas have the greatest volume?

	Temperature	Pressure
A.	low	low
B.	low	high
C.	high	high
D.	high	low

16. Which of the following contains the greatest number of molecules?

17. Which of the following compounds has/have the empirical formula CH2O? I. CH3COOH II. C6H12O6 III.    C12H22O11

18. Assuming complete reaction, what volume of 0.200 mol dm–3 HCl(aq) is required to neutralize 25.0 cm3 of 0.200 mol dm–3 Ba(OH)2(aq)?  

19. Under what conditions would one mole of methane gas, CH4, occupy the smallest volume?

20. The temperature in Kelvin of 2.0 dm3 of an ideal gas is doubled and its pressure is increased by a factor of four. What is the final volume of the gas?

21. Which is a correct definition of the term empirical formula?

22. The reaction of ethanal and oxygen can be represented by the unbalanced equation below. __ CH3CHO + __ O2 → __ CO2 + __ H2O When the equation is balanced using the smallest possible integers, what is the coefficient for O2?

23. The equation for the complete combustion of butane is 2C4H10 + 13O2 → 8CO2 + 10H2O What is the amount (in mol) of carbon dioxide formed by the complete combustion of three moles of butane?

24. Which solution contains the greatest amount (in mol) of solute?

25. A fixed mass of an ideal gas has a volume of 800 cm3 under certain conditions. The pressure (in kPa) and temperature (in K) are both doubled. What is the volume of the gas after these changes with other conditions remaining the same?

26. The complete oxidation of propane produces carbon dioxide and water as shown below. C3H8 + __O2 →__CO2 + __H2O What is the total of the coefficients for the products in the balanced equation for 1 mole of propane?

27. The relative molecular mass (Mr) of a compound is 60. Which formulas are possible for this compound? I. CH3CH2CH2NH2 II.CH3CH2CH2OH III.    CH3CH(OH)CH3

28. Which sample has the least number of atoms?

29. Avogadro’s constant has the same value as the number of

30. What is the total of all the coefficients in the balanced equation for the reduction of 1 mol of MnO4–? __ MnO4– +__H+ + __ e– →__Mn2+ + __H2O

31. Which contains the same number of ions as the value of Avogadro’s constant?

32. A reaction occurring in the extraction of lead from its ore can be represented by this unbalanced equation: __ PbS + __O2 → __ PbO + __ SO2 When the equation is balanced using the smallest possible whole numbers, what is the coefficient for O2?

33. The equation for a reaction occurring in the synthesis of methanol is CO2 + 3H2 → CH3OH + H2O What is the maximum amount of methanol that can be formed from 2 mol of carbon dioxide and 3 mol of hydrogen?

34. Which solution contains 0.1 mol of sodium hydroxide?

35. A cylinder of gas is at a pressure of 40 kPa. The volume and temperature (in K) are both doubled. What is the pressure of the gas after these changes?

36. Which of the following quantities has units?

37. The empirical formula of a compound is C2H4O. Which molecular formulas are possible for this compound? I. CH3COOH II. CH3CH2CH2COOH III.    CH3COOCH2CH3

38. Calcium carbonate decomposes on heating as shown below. CaCO3 → CaO + CO2 When 50 g of calcium carbonate are decomposed, 7 g of calcium oxide are formed. What is the percentage yield of calcium oxide?

39. Sodium reacts with water as shown below. __ Na + __ H2O → __ NaOH + __ H2 What is the total of all the coefficients when the equation is balanced using the smallest possible whole numbers?

40. What is the total number of ions present in the formula, Al2(SO4)3?

41. A 4 g sample of sodium hydroxide, NaOH, is dissolved in water and made up to 500 cm3 of aqueous solution. What is the concentration of the resulting solution?

42. Methane, CH4, burns in oxygen gas to form carbon dioxide and water. How many moles of carbon dioxide will be formed from 8.0 g of methane?

43. What is the empirical formula of a compound containing 50% by mass of element X (Ar = 20) and 50% by mass of element Y (Ar = 25)?

44. Assuming complete reaction, what volume of 0.200 mol dm–3 potassium hydroxide solution (KOH(aq)), is required to neutralize 25.0 cm3 of 0.200 mol dm–3 aqueous sulfuric acid, (H2SO4(aq))?

45. Consider the following reaction. N2(g) + 3H2(g)  2NH3(g) If the reaction is made to go to completion, what volume of ammonia (in dm3) can be prepared from 25 dm3 of nitrogen and 60 dm3 of hydrogen? All volumes are measured at the same temperature and pressure.

46. The temperature in Kelvin of 1.0 dm3 of an ideal gas is doubled and its pressure is tripled. What is the final volume of the gas in dm3?

47. On complete combustion, a sample of a hydrocarbon compound produces 1.5 mol of carbon dioxide and 2.0 mol of water. What is the molecular formula of this hydrocarbon?

48. When excess BaCl2(aq) was added to a sample of Fe(NH4)2(SO4)2(aq) to determine the amount in moles of sulfate present, 5.02×10–3 mol of BaSO4 was obtained. How many moles of sulfate ions and iron ions were in the sample of Fe(NH4)2(SO4)2?

	Amount of sulfate ions / moles	Amount of iron ions / moles
A.	5.02×10–3	2.51×10–3
B.	10.04×10–3	5.02×10–3
C.	2.51×10–3	5.02×10–3
D.	10.04×10–3	2.51×10–3

49. What volume of 0.500 mol dm–3 sulfuric acid solution is required to react completely with 10.0 g of calcium carbonate according to the equation below? CaCO3(s) + H2SO4(aq) → CaSO4(aq) + H2O(l) + CO2(g)

50. Which expression gives the amount (in mol) of a substance, if the mass is given in grams?

51. What is the total number of atoms in 0.20 mol of propanone, CH3COCH3?

52. When the equation below is balanced for 1 mol of C3H4, what is the coefficient for O2? C3C4 + _O2 → _CO2 + _H2O

53. Ethyne, C2H2, reacts with oxygen according to the equation below. What volume of oxygen (in dm3) reacts with 0.40 dm3 of C2H2? 2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(g)

54. Ethyne, C2H2, reacts with oxygen according to the equation below. What volume of oxygen (in dm3) reacts with 0.40 dm3 of C2H2? 2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(g)

55. What is the coefficient for H+ when the redox equation below is balanced? __Ag(s) + __NO3–(aq) +__H+(aq) → __Ag+(aq) + __NO(g) + __H2O(l)

56. How many hydrogen atoms are in one mole of ethanol, C2H5OH?

57. What is the coefficient for H2SO4(aq) when the following equation is balanced, using the smallest possible integers? __Mg3N2(s) + __H2SO4(aq) → __MgSO4(aq) + __(NH4)2SO4(aq)

58. Air bags in cars inflate when sodium azide decomposes to form sodium and nitrogen: 2NaN3(s) → 2Na(s) + 3N2(g) Calculate the amount, in moles, of nitrogen gas produced by the decomposition of 2.52 mol of NaN3(s).

59. What volume, in cm3, of 0.200 mol dm–3 HCl(aq) is required to neutralize 25.0 cm3 of 0.200 mol dm–3 Ba(OH)2(aq)?