pH

1
pH
2
pH

• pH is a measurement of acidity
• Acids have a ph less than 7
• Alkalis have a pH greater than 7
• Strong acids have a pH of approximately 1
• Weak acids have a pH of 4-6
• Weak alkalis have a pH of 8-10
• Strong alkalis have a pH of approx 14

3
Indicators

• These are chemicals that change colour to show
  you the pH
• Red Litmus goes blue in alkalis
• Blue Litmus goes red in Acid
• Universal indicator changes into various colours
  to indicate pH

4
Indicators
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Ethan tested some caustic soda with universal
indicator It turned purple What is it?
Strong acid
Neutral
Weak alkali
Strong alkali
5
Correct
6
Reactions of Acids and Alkalis
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pH 2
Alkalis neutralise acids You mix equal
quantities of Nitric acid and Sodium
Hydroxide What will be the most likely pH of the
mixture?
pH 5
pH 7
pH 9
pH 14
7
Correct
8
Reactions of Acids and Alkalis
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Rennies contain sodium hydrogen carbonate. You
take them to neutralise the contents of your
stomach What colour would blue litmus change to
before you take Rennies?
No change
Red
Green
Purple
9
Correct
10
pH
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Orange
People put lemon juice into some drinks to make
them taste sharp or sour. What colour would
lemon juice make universal indicator go?
Green
Blue
Purple
11
Correct
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12
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