acids (lesson 1) acids and bases. what’s your favorite drink?
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ACIDS(LESSON 1)
Acids and bases
What’s your favorite drink?
Food for thought
What causes the erosion of the tooth?What is the reason behind this phenomenon?
Lesson objectives
Define acid in terms of ions produced in aqueous solution.
State and describe the chemical properties of acids.
State the physical properties of acids.Recognize and understand the use of litmus
paper and universal indicators.
Acids in action!
Common Acids Chemical Formula
Uses
Sulfuric acid H2SO4 Make detergent, fertilisers and soaps.Used in car batteries.
Hydrochloric acid HCl Remove rust from body of a car before painting.
Nitric acid HNO3 Make fertilisers
Ethanoic Acid (Vinegar)
CH3COOH Preserve vegetables.
Citric Acid C6H8O7 Found in fruits- orange and lemon.
When water is added into acid…
Sulfuric acidH2SO4 (aq) 2H+ (aq) + SO4
2-(aq)
Hydrochloric acidHCl (aq) H+ (aq) + Cl-(aq)
What do you notice about these two
equations?
What do you notice about these two
equations?
1 minute to think and discuss with your partner.
Hint: Three points to note. Focus on the product and the state symbols.
Sulfuric acidH2SO4 (aq) 2H+ (aq) + SO4
2-(aq)
Hydrochloric acidHCl (aq) H+ (aq) + Cl-(aq)
In both equations, 1. An anion and a cation is produced. 2. Cation is H+ 3. The acid and ions formed are in
aqueous state.
In both equations, 1. An anion and a cation is produced. 2. Cation is H+ 3. The acid and ions formed are in
aqueous state.
Sulfuric acidH2SO4 (aq) 2H+ (aq) + SO4
2-(aq)
Hydrochloric acidHCl (aq) H+ (aq) + Cl-(aq)
Dissociation/ Ionization of acids. i.e. Acid is being ionized in water to form H+ ions and SO4
2- ions.
Definition of an acid
An acid is a substance that produces hydrogen ions, H+(aq), when dissolved in water.
ExampleHNO3(aq) H+(aq) + NO3
-(aq)Role of water in acidic propertiesAcids only display the properties of acids when they are dissolved in water. Acids dissociate in water to produce H+ ions which are responsible for the acidic properties.
Nitric Acid
Chemical properties of acids
Acids can take part in the following reactions:
1.Acids + metals 2.Acids + metal carbonates3.Acids + bases (Metal oxides / Metal hydroxides)
Acid + metals
Acids react with reactive metals to form hydrogen gas and salt.
General word equationmetal + acid salt + hydrogen
Mg(s) + H2SO4(aq) MgSO4(aq) +H2(g)
Note:A salt is a compound obtained when the hydrogen of an acid is replaced by a metal or an ammonium ion, NH4
+
Salt of sulfuric acid sulfates
Salt of nitric acid nitrates
Salt of hydrochloric acid chlorides
magnesium
Dilute sulfuric acid Magnesium sulfateHydrogen
Acid + metal carbonates
Acid reacts with metal carbonates to form salt, carbon dioxide and water.
General word equation:
acid + metal carbonate salt + water + carbon dioxide
Example:Na2CO3(s) + 2HCl(aq) 2NaCl(aq) + H2O(l) +CO2(g) Sodium carbonate
Dilute hydrochloric acid
Sodium chloride
Water Carbon dioxide
Acid + bases
Acid reacts with bases (metal oxide or metal hydroxide) to form salt and water only. This reaction is known as neutralisation.
General word equation:Acid + metal oxide/ metal hydroxide salt + water
Example:
ZnO(s) + H2SO4(aq) ZnSO4(aq) + H2O(l)Zinc oxide
Dilute sulfuric acid
Zinc sulfate
Water
Physical Properties of Acid
Acids have sour taste.
In acids, the free moving ions are able to conduct electricity.
Physical Properties of Acid
Acids are corrosive.
Physical Properties of Acid
Acids turn damp blue litmus paper red.
Acids have pH values of less than 7.
What have we learnt today?
What are acids?Examples of common acids and their uses.The chemical properties of acidsThe physical properties of acids
Mini Checkpoint
Write the chemical equations for the following reactions:
1.Magnesium and hydrochloric acid2.Zinc oxide and nitric acid3.Calcium carbonate and nitric acid
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