C5 Revision Booklet

7/31/2019 C5 Revision Booklet

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C5. How much?

Weigh and See

The formula of a compound can be found if the massesor percentages of the reacting chemicals are known.

For example, the formula of magnesium oxide can befound by burning a known mass of magnesium in acrucible and weighing the amount of magnesium oxideformed.

Sample results: mass of crucible + lid = 20,2 g

mass of crucible + lid + magnesium = 22,6 g

mass of crucible + lid + magnesium oxide = 24,2 g

1. What is the mass of magnesium burned?

2. What is the mass of magnesium oxide produced?

3. Write a word and symbol equation for the reaction takingplace

4. Why does the mass of the reaction appear to increase?

5. What is meant by conservation of mass in a reaction?

6. Give an example of a reaction where the mass appears to

have decreased

7. Explain what has really happened


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Moles and Empirical formula.

8. Write down a formal definition of a mole

Remember the mass of 1 mole of a substance is called themolar mass. The molar mass is the relative formula mass ingrammes

9. Calculate the molar mass of each of the followingsubstancessubstance Molar mass substance Molar massN2 CO2Cl2 CaCO3CH4 (NH4)2SO4

10. Define what is meant by Empirical formula

11. What is the Empirical formula of glucose C6H12O6

12. What is the Empirical formula of ethanoic acid? CH3COOH

13. Define the term Relative Atomic Mass RAM

14. 132g of a compound contains 36g of carbon and 96g ofoxygen. Calculate the Empirical formula


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15. Calculate the Empirical formula of a compound thatcontains 2.04%H, 32.65%S and 65.31% O

Electrolysis.

16.Label the diagramto show:

- Positive electrode- Negative

electrode

- Electrolyte- Label the + and

terminals on thebattery

17. Draw a cation and anion in the solution and show whichway they would move18. What is an electrolyte and why do they have to bemolten?

19. Name the ions present in the following electrolytes andidentify the charge on each


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Electrolyte Positive ion Negative ionKClPbBr2

H2OAl2O3

20. Complete the following table to show the half equationsat the anode and cathodeElectrolyte Half equation at

the cathodeHalf equation atthe anode

H2OAl2O3

21. Explain what can happen if the electrolyte is a solutiongive examples

22. Explain why this isa special case andwhat it is used for

23. Write down the equations that take place at the anodeand the cathode


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Quantitative Analysis

24. What is meant by RDA ?

25. Tin A of beans contains 1.2g of sodium. Tin B contains2.8g of salt. Which contains the most?

26. 0.1g of sodium hydroxide is dissolved in 200cm3 of water.What is the concentration in g/dm3 ?

27. How many moles of salt are in 3dm3 of a 0.5m/dm3

solution?

28. List the other sodiumcompounds that are found in foods

Titrations.

29. The picture shows a pH meter

that is used to test soilWhat numbers would indicate anacid?

Neutral?


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An alkali ?

30. Look at thecolour chart forUniversalindicator. Whatmakes this a goodindicator to use?

31. Why would itnot be the best touse in a titration?

32. What happens to the pH number when an acid reactswith an alkali?

33. What is the general equation for an acid reacting

with an alkali?

34. Label the graph with:

End point

All alkali isneutralized

Acid has reactedwith some of thealkali

Excess acid pHbelow 7


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Alkali pH high

35. Label the apparatus shown. What would be used to

measure out the liquid in the conical flask

36. Explain how to carry out a titration in no more than 5steps

37. What type if indicators are most suitable to use fortitrations?

38. Why is it important to carry out repeat titrations?

39. There is only one equation you need to know to carryout titrations. Represent it in its rearranged forms

concentration = number of molesvolume in dm3


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In a titration 24.5cm3 of a 0.5m/dm3 solution ofhydrochloric acid reacts with 29cm3 of sodiumhydroxide solution.

40. Write out a symbol equation for the reaction betweenNaOH and HCl and balance it

41. How many moles of acid were present?

42. How many moles of alkali were present?

43. What was the concentration of alkali?

Gas Volumes .

44. Name other ways that can be used to collect andmeasure gases apart form the syringe

44. Plot the data on the graph paper below

Time inseconds

0 20 40 60 80 100 120


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Totalvolume incm3

0 16 28 36 40 42 42

45. When was thereaction thefastest?

46. When did thereaction stop?

47. Illustrate on yourgraph how youcan see the totalvolume of gas produced

48. Explain what is meant by the limiting reactant

49. What does the gradient of the curve show?

Equilibria.

50. What is meant by equilibrium?


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51. What is made in the Haber process?

52. What is this product used for?

53. How do we get the reactants needed for the HaberProcess?

54. Write out the overall equation for the Haber process

55. What are the conditions for the Haber process?-temperature =-pressure =-catalyst =

56. Explain how changing the reaction conditions can

change the position of the equilibriumconcentration

pressure


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temperature

Strong and Weak Acids.

57. List some strong acids and weak acids in the tableStrong acids Weak acids

58. Why are acids acidic?

59. Explain the difference between a strong and a weakacid

60. Define a weak acid using the terms H+ ions,pH,equilibrium, reversible reaction

62. Explain why weak acids can be useful

61. Write a symbol equation for the ionization of ethanoicacid


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62. Define concentration and strength in terms of acid

Concentration Strength

Ionic Equations.

63. What is meant by a precipitation reaction?

64. Write out the word equation for the

Reaction between lead nitrate and potassium iodide

65. Using the formulas Pb(NO3)2 , KI, KNO3, PbI2Write the symbol equation for the reaction

66. What is the precipitate

67. Write out an ionic equation for the reaction


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68. Identify the spectator ions

69. What colour precipitates are produced by chlorides,bromides and iodides when silver nitrate is added tosolutions of these solutions

ColourChlorideBromideIodide

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C5 Revision Booklet