1. Acidity, pH, and Indicators

2. At this point, you should be familiar with the general properties of acids and bases.

3. At this point, you should be familiar with the general properties of acids and bases. If not, make sure you review them at this time.

4. pH of Acidic, Basic, and Neutral Solutions

5. The degree of acidity,

6. The degree of acidity, or how acidic a solution is,

7. The degree of acidity, or how acidic a solution is, is often represented by a quantity called pH.

8. “pH” has a small “p” and a capital “H”. pH is just a number,

9. The degree of acidity, or how acidic a solution is, is often represented by a quantity called pH. “pH” has a small “p” and a capital “H”. pH is just a number, there is no unit for it.

10. You should know what the general range in pH is for acidic solutions,

11. You should know what the general range in pH is for acidic solutions, basic solutions,

12. You should know what the general range in pH is for acidic solutions, basic solutions, and neutral solutions.

13. You should know what the general range in pH is for acidic solutions, basic solutions, and neutral solutions. The pH scale diagram in the Science 10 data booklet will help you with this:

15. Let’s have a look at the information in this scale:

17. A Neutral solution has a pH = 7.0

18. Let’s have a look at the information in this scale: A Basic solution has a pH >7.0

19. Let’s have a look at the information in this scale: Getting more basic

20. Let’s have a look at the information in this scale: Getting more acidic

21. Getting more basic

22. Getting more corrosive

23. Quite corrosive

24. Getting more corrosive Quite corrosive

25. Getting more corrosive Non - corrosive

26. A More Detailed Look at pH

27. Like the Richter Scale used for comparing strength’s of earthquakes, the pH scale is a logarithmic scale.

28. All you are required to know about this here, is that a change of one whole number in pH value represents a ten-fold change in acidity.

29. 10 × more acidic A solution with a pH of 3 is 10 times more acidic than a solution with a pH of 4

30. A solution with a pH of 2 is 10 times more acidic than a solution with a pH of 3 10 × more acidic

31. ? × more acidic How many times more acidic is a pH of 2 than a pH of 4?

32. 100 × more acidic 10 × more acidic

33. 10 Change to Scientific Notation 100 × more acidic 10 × more acidic

34. Change to Scientific Notation 10 2 × more acidic 10 1 × more acidic

39. A solution with a pH of 9 is times (more/less) acidic than a solution with a pH of 3.

40. A solution with a pH of 9 is times (more/less) acidic than a solution with a pH of 3.

41. A solution with a pH of 9 is times (more/less) acidic than a solution with a pH of 3.

42. A solution with a pH of 9 is times (more/less) acidic than a solution with a pH of 3.

43. A solution with a pH of 9 is times (more/less) acidic than a solution with a pH of 3.

44. A solution with a pH of 9 is times (more/less) acidic than a solution with a pH of 3.

45. A solution with a pH of 9 is times (more/less) acidic than a solution with a pH of 3. or 1 million

46. A solution with a pH of 9 is10 6 times (more/less) acidic than a solution with a pH of 3. or 1 million

47. A solution with a pH of 9 is10 6 times (more/less) acidic than a solution with a pH of 3. or 1 million ?

48. A solution with a pH of 9 is10 6 times (more/less) acidic than a solution with a pH of 3. or 1 million The higher the pH of a solution is, the less acidic it is.

49. A solution with a pH of 9 is10 6 times less acidic than a solution with a pH of 3. or 1 million The higher the pH of a solution is, the more basic, or less acidic it is.

50. A solution with a pH of 9 is10 6 times less acidic than a solution with a pH of 3. The higher the pH of a solution is, the more basic, or less acidic it is.

51. A solution with a pH of 9 is10 6 times less acidic than a solution with a pH of 3. The higher the pH of a solution is, the more basic, or less acidic it is. A solution with a pH of 9 is one million times less acidic than a solution with a pH of 3.

52. pH Indicators

53. A pH indicator is a substance that changes colour when a certain change in pH occurs.

54. For example, litmus is a familiar indicator.

55. A pH indicator is a substance that changes colour when a certain change in pH occurs. For example, litmus is a familiar indicator. Paper soaked in litmus is called litmus paper and it is used to test substances to see if they are acidic, basic, or neutral.

56. There are two main types of litmus paper:

57.  red litmus paper

58. There are two main types of litmus paper:  red litmus paper  blue litmus paper

59. TypeAdd to an AcidAdd to a Base red litmus blue litmus There are two main types of litmus paper:  red litmus paper  blue litmus paper

60. TypeAdd to an AcidAdd to a Base red litmus blue litmus There are two main types of litmus paper:  red litmus paper  blue litmus paper

61. TypeAdd to an AcidAdd to a Base red litmusstays red blue litmus There are two main types of litmus paper:  red litmus paper  blue litmus paper

62. TypeAdd to an AcidAdd to a Base red litmusstays red blue litmus There are two main types of litmus paper:  red litmus paper  blue litmus paper

63. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmus There are two main types of litmus paper:  red litmus paper  blue litmus paper

64. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmus There are two main types of litmus paper:  red litmus paper  blue litmus paper

65. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmus There are two main types of litmus paper:  red litmus paper  blue litmus paper

66. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns red There are two main types of litmus paper:  red litmus paper  blue litmus paper

67. There are two main types of litmus paper:  red litmus paper  blue litmus paper TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns red

68. There are two main types of litmus paper:  red litmus paper  blue litmus paper TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue

69. TypeAdd to an Neutral water red litmus blue litmus There are two main types of litmus paper:  red litmus paper  blue litmus paper

70. TypeAdd to an Neutral water red litmus blue litmus There are two main types of litmus paper:  red litmus paper  blue litmus paper

71. TypeAdd to an Neutral water red litmusstays red blue litmus There are two main types of litmus paper:  red litmus paper  blue litmus paper

72. There are two main types of litmus paper:  red litmus paper  blue litmus paper TypeAdd to an Neutral water red litmusstays red blue litmus

73. There are two main types of litmus paper:  red litmus paper  blue litmus paper TypeAdd to an Neutral water red litmusstays red blue litmus

74. There are two main types of litmus paper:  red litmus paper  blue litmus paper TypeAdd to an Neutral water red litmusstays red blue litmusstays blue

75. TypeAdd to an Neutral water red litmusstays red blue litmusstays blue There are two main types of litmus paper:  red litmus paper  blue litmus paper Adding either type of litmus paper to neutral water will not change its colour.

76. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue If we have an unknown solution and we want to find out whether it is acidic, basic, or neutral, Adding either type of litmus paper to neutral water will not change its colour.

77. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue If we have an unknown solution and we want to find out whether it is acidic, basic, or neutral, we could dip red and blue litmus paper into it Adding either type of litmus paper to neutral water will not change its colour.

78. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue If we have an unknown solution and we want to find out whether it is acidic, basic, or neutral, we could dip red and blue litmus paper into it and from the results and the information below, Adding either type of litmus paper to neutral water will not change its colour.

79. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue If we have an unknown solution and we want to find out whether it is acidic, basic, or neutral, we could dip red and blue litmus paper into it and from the results and the information below, we could find out whether it is acidic, basic, or neutral. Adding either type of litmus paper to neutral water will not change its colour.

80. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue For example, you have a solution called Unknown 1 and: Adding either type of litmus paper to neutral water will not change its colour.

81. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue For example, you have a solution called Unknown 1 and:  Red litmus paper stays red Adding either type of litmus paper to neutral water will not change its colour.

82. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue For example, you have a solution called Unknown 1 and:  Red litmus paper stays red  Blue litmus paper stays blue Adding either type of litmus paper to neutral water will not change its colour.

83. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue For example, you have a solution called Unknown 1 and:  Red litmus paper stays red  Blue litmus paper stays blue Then Unknown 1 is Adding either type of litmus paper to neutral water will not change its colour.

84. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue For example, you have a solution called Unknown 1 and:  Red litmus paper stays red  Blue litmus paper stays blue Then Unknown 1 is neutral Adding either type of litmus paper to neutral water will not change its colour.

85. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue For example, you have a solution called Unknown 2 and: Adding either type of litmus paper to neutral water will not change its colour.

86. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue For example, you have a solution called Unknown 2 and:  Red litmus paper stays red Adding either type of litmus paper to neutral water will not change its colour.

87. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue For example, you have a solution called Unknown 2 and:  Red litmus paper stays red  Blue litmus paper turns red Adding either type of litmus paper to neutral water will not change its colour.

88. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue For example, you have a solution called Unknown 2 and:  Red litmus paper stays red  Blue litmus paper turns red Then Unknown 2 is Adding either type of litmus paper to neutral water will not change its colour.

89. TypeAdd to an AcidAdd to a Base red litmusstays redturns blue blue litmusturns redstays blue For example, you have a solution called Unknown 2 and:  Red litmus paper stays red  Blue litmus paper turns red Then Unknown 2 is acidic Adding either type of litmus paper to neutral water will not change its colour.

90. Litmus paper is handy for identifying solutions as either acidic, basic or neutral.

92. Litmus changes colour at a pH of 7

93. Litmus paper is handy for identifying solutions as either acidic, basic or neutral. If pH is below 7, litmus is red

94. Litmus paper is handy for identifying solutions as either acidic, basic or neutral. If pH is above 7, litmus is blue

95. Different indicators change colour at different pH values.

96. Indicators change colour gradually, over a range of pHs. 3.24.4 Sloped line between pH = 3.2 and 4.4

97. Indicators change colour gradually, over a range of pHs. 3.24.4 yellowred Methyl Orange gradually changes from red to yellow between pH = 3.2 to 4.4

98. Indicators change colour gradually, over a range of pHs. 3.24.4 Methyl Orange gradually changes from red to yellow between pH = 3.2 to 4.4 orangeyellowred

99. Indicators change colour gradually, over a range of pHs. 3.24.4 Methyl Orange gradually changes from red to yellow between pH = 3.2 to 4.4 orangeyellowred

100. Indicators change colour gradually, over a range of pHs. 3.24.4 Methyl Orange gradually changes from red to yellow between pH = 3.2 to 4.4 orangeyellowred

101. Indicators change colour gradually, over a range of pHs. 3.24.4 orangeyellowred Methyl Orange gradually changes from red to yellow between pH = 3.2 to 4.4

102. Methyl Red changes from red to yellow from pH 4.8 to 6.0

103. Bromthymol Blue changes from yellow to blue from pH 6.0 to 7.6

104. Using this table, we can see what colours different indicators are at a given pH.

105. Colours of Various Indicators at a pH of 2

106. At pH =2:  Methyl Orange is red  Methyl Red is red  Bromthymol Blue is yellow  Litmus is red  Phenolphthalein is colourless  Indigo carmine is blue Colours of Various Indicators at a pH of 2

107. At pH =2:  Methyl Orange is red  Methyl Red is red  Bromthymol Blue is yellow  Litmus is red  Phenolphthalein is colourless  Indigo carmine is blue Colours of Various Indicators at a pH of 2

108. At pH =2:  Methyl Orange is red  Methyl Red is red  Bromthymol Blue is yellow  Litmus is red  Phenolphthalein is colourless  Indigo carmine is blue Colours of Various Indicators at a pH of 2

109. At pH =2:  Methyl Orange is red  Methyl Red is red  Bromthymol Blue is yellow  Litmus is red  Phenolphthalein is colourless  Indigo carmine is blue Colours of Various Indicators at a pH of 2

110. At pH =2:  Methyl Orange is red  Methyl Red is red  Bromthymol Blue is yellow  Litmus is red  Phenolphthalein is colourless  Indigo carmine is blue Colours of Various Indicators at a pH of 2

111. Colours of Various Indicators at a pH of 11

112. At pH =11:  Methyl Orange is yellow  Methyl Red is yellow  Bromthymol Blue is blue  Litmus is blue  Phenolphthalein is pink  Indigo carmine is blue Colours of Various Indicators at a pH of 11

113. At pH =11:  Methyl Orange is yellow  Methyl Red is yellow  Bromthymol Blue is blue  Litmus is blue  Phenolphthalein is pink  Indigo carmine is blue Colours of Various Indicators at a pH of 11

114. At pH =11:  Methyl Orange is yellow  Methyl Red is yellow  Bromthymol Blue is blue  Litmus is blue  Phenolphthalein is pink  Indigo carmine is blue Colours of Various Indicators at a pH of 11

115. At pH =11:  Methyl Orange is yellow  Methyl Red is yellow  Bromthymol Blue is blue  Litmus is blue  Phenolphthalein is pink  Indigo carmine is blue Colours of Various Indicators at a pH of 11

116. Question: A solution is yellow in bromthymol blue, yellow in methyl red, and blue in indigo carmine. The pH is: a) 4.0 b) 6.0 c) 7.0 d) 8.0

127. Question: A solution is yellow in methyl orange, pink in phenolphthalein, and green in indigo carmine. The pH is: a) 5.0 b) 6.5 c) 12.5 d) 14.0