Acids and
Alkalis
Physical and Chemical
Properties
Properties of Acids
1. Acids have sour taste.
2. Acids are corrosive.
3. Acids dissolve in water to form solutions
which c...
Acids in Food
o Citric acid (in lemons)
o Ethanoic acid (in vinegar)
o Carbonic acid (in soft drinks)
o Tartaric acid (in ...
An acid is a substance which produces
hydrogen ions when it is dissolved in water.
The hydrogen ions give an acid its acid...
TAKE NOTE
NOT all substances that contain
hydrogen are acids.
For example,
•NH3 (ammonia) contains hydrogen but it is not
...
Properties of Alkalis
1. Alkalis have bitter taste.
2. Alkalis have soapy feel.
3. Alkalis dissolve in water to form solut...
• An alkali is a substance
which produces
hydroxide ions when it is
dissolved in water.
• The hydroxide ions,
OH-
(aq) giv...
An acid is a substance which produces hydrogen
ions when it is dissolved in water.
Summary
What is an acid?
Hydrochloric a...
An alkali is a substance which produces
hydroxide ions when it is dissolved in water.
Summary
What is an alkali?
Sodium hy...
Indicators
o An indicator is a substance which changes colour
depending on whether the solution tested is acidic or
alkali...
Litmus Indicator
• Acids turn blue litmus paper red.
o Litmus paper exists in two colours, red and blue.
• Alkalis turn re...
Acids + Metals
Acids react with some metals to form a salt and
hydrogen gas.
hydrochloric
acid magnesium
magnesium
chlorid...
Acids + Metals
 The type and name of salt depends on the acid used.
Reaction with
• Hydrochloric acid 
• Sulfuric acid ...
Acids + Metals
Acids react with some metals to form a salt and
hydrogen gas.
Some metals which can react with acids are m...
Acids + Metals
How to test for hydrogen gas?
 Place a lighted splint in the presence of the gas.
 If hydrogen is present...
Acids + Carbonates
Acids react with carbonates to form a salt, carbon
dioxide gas and water.
2
hydrochloric
acid
sodium
ca...
Acids + Carbonates
How to test for carbon dioxide gas?
 Bubble the gas through limewater.
 Carbon dioxide forms a white ...
Acids + Carbonates
How to test for carbon dioxide gas?
 Bubble the gas through limewater.
 Carbon dioxide forms a white ...
Acids + Alkalis
Acids react with alkalis to form a salt and water only.
The reaction between acids and alkalis is called
...
Acids + Alkalis
Examples:
hydrochloric
acid
sodium
hydroxide
sodium
chloride
Water+  +
sulfuric acid
potassium
hydroxide
...
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Chemistry - acids and alkali

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Basics of Chemistry on Acids and Alkalis

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Chemistry - acids and alkali

  1. 1. Acids and Alkalis Physical and Chemical Properties
  2. 2. Properties of Acids 1. Acids have sour taste. 2. Acids are corrosive. 3. Acids dissolve in water to form solutions which conduct electricity.
  3. 3. Acids in Food o Citric acid (in lemons) o Ethanoic acid (in vinegar) o Carbonic acid (in soft drinks) o Tartaric acid (in grapes) o Malic acid (in apples) o Lactic acid (in yoghurt) Weak organic acids found in food
  4. 4. An acid is a substance which produces hydrogen ions when it is dissolved in water. The hydrogen ions give an acid its acidic properties. Acids only behave as acids when they are dissolved in water. What is an Acid?
  5. 5. TAKE NOTE NOT all substances that contain hydrogen are acids. For example, •NH3 (ammonia) contains hydrogen but it is not an acid. •H2 (hydrogen) is also not an acid.
  6. 6. Properties of Alkalis 1. Alkalis have bitter taste. 2. Alkalis have soapy feel. 3. Alkalis dissolve in water to form solutions which conduct electricity.
  7. 7. • An alkali is a substance which produces hydroxide ions when it is dissolved in water. • The hydroxide ions, OH- (aq) give an alkali its alkaline properties. • Alkalis only behave as alkalis when they are dissolved in water. What is an Alkali?
  8. 8. An acid is a substance which produces hydrogen ions when it is dissolved in water. Summary What is an acid? Hydrochloric acid, sulfuric acid, nitric acid, ethanoic acid, citric acid … Examples of acids?
  9. 9. An alkali is a substance which produces hydroxide ions when it is dissolved in water. Summary What is an alkali? Sodium hydroxide, potassium hydroxide, calcium hydroxide, aqueous ammonia Examples of alkalis?
  10. 10. Indicators o An indicator is a substance which changes colour depending on whether the solution tested is acidic or alkaline. o There are many types of indicators, including the universal indicator and litmus indicator.
  11. 11. Litmus Indicator • Acids turn blue litmus paper red. o Litmus paper exists in two colours, red and blue. • Alkalis turn red litmus paper blue.
  12. 12. Acids + Metals Acids react with some metals to form a salt and hydrogen gas. hydrochloric acid magnesium magnesium chloride hydrogen gas +  + sulfuric acid magnesium magnesium sulfate hydrogen gas +  + 1 Acid + Metal  Salt + Hydrogen gas
  13. 13. Acids + Metals  The type and name of salt depends on the acid used. Reaction with • Hydrochloric acid  • Sulfuric acid  • Nitric acid  Chloride salts Sulfate salts Nitrate salts
  14. 14. Acids + Metals Acids react with some metals to form a salt and hydrogen gas. Some metals which can react with acids are magnesium, aluminium, zinc and iron. Explosive reactions occur when using reactive metals like lithium, sodium and potassium. Exception: Unreactive metals such as copper and silver do not react with dilute acids.
  15. 15. Acids + Metals How to test for hydrogen gas?  Place a lighted splint in the presence of the gas.  If hydrogen is present, the lighted splint will be extinguished with a ‘pop’ sound.
  16. 16. Acids + Carbonates Acids react with carbonates to form a salt, carbon dioxide gas and water. 2 hydrochloric acid sodium carbonate sodium chloride carbon dioxide gas +  + nitric acid calcium carbonate calcium nitrate +  water+ carbon dioxide gas + water+ Acid + Carbonate  Salt + Carbon dioxide gas + Water
  17. 17. Acids + Carbonates How to test for carbon dioxide gas?  Bubble the gas through limewater.  Carbon dioxide forms a white precipitate with limewater.
  18. 18. Acids + Carbonates How to test for carbon dioxide gas?  Bubble the gas through limewater.  Carbon dioxide forms a white precipitate with limewater. Limewater Bubble carbon dioxide gas White precipitate formed
  19. 19. Acids + Alkalis Acids react with alkalis to form a salt and water only. The reaction between acids and alkalis is called neutralisation. 3 Acid + Alkali  Salt + Water
  20. 20. Acids + Alkalis Examples: hydrochloric acid sodium hydroxide sodium chloride Water+  + sulfuric acid potassium hydroxide potassium sulfate Water+  +

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