CHEMISTRY FORM 1
- 1.1 What is matter?
- 1.2 What is Chemistry?
- 1.3 What does matter consist of?
- 1.4 Are the particles in matter stationary?
- 1.5 Arrangement, distance, and attraction between particles
- 1.6 Properties of matter (volume, shape and compression)
- 1.7 Conductors and non-conductors
- 1.8 Sources of heat
- 1.9 Bunsen burner
- 1.10 Role of Chemistry in society
- 2.1 Pure substances
- 2.2 Mixtures
- 2.3 Separation of Mixtures
- 2.4 Separation of solid-solid mixture
- 2.5 Separation of insoluble solid-liquid mixture
- 2.6 Separation of soluble solid-liquid mixture (solution)
- 2.7 Separation of immiscible liquid-liquid mixture
- 2.8 Separation of miscible liquid-liquid mixtures (solution)
- 2.9 Separation of a liquid-gas mixture
- 2.10 Selecting and using appropriate methods of separating mixtures
- 2.11 Kinetic theory of matter
- 2.12 Classification by physical states
- 2.13 Effect of heat on physical states
- 2.14 Effect of impurities on melting and boiling points
- 2.15 Permanent and non-permanent changes
- 2.16 Definitions, chemical symbols and equations
- 3.1 Simple acid-base indicators
- 3.2 Universal indicators and pH scale
- 3.3 Reactions of acids with metals
- 3.4 Reactions of acids with carbonates and hydrogen-carbonates
- 3.5 Reactions of acids with bases
- 3.6 Effects of acids on substances
- 3.7 Applications of acids and bases
- 4.1 Composition of Air
- 4.2 Fractional distillation of liquid air
- 4.3 Rusting
- 4.4 Oxygen
- 4.5 Burning of substances in air
- 4.6 Atmospheric pollution
- 5.1 Candle wax and water
- 5.2 Reactions of metals with liquid water
- 5.3 Reaction of metals with steam
- 5.4 Preparation of hydrogen gas
Acids, Bases and Indicators: Reactions of acids with bases
3.0 Acids, Bases and Indicators
3.5 Reactions of acids with bases
Bases are oxides and hydroxides of metals. Examples are copper (II) oxide, zinc oxide, magnesium oxide, lead (II) oxide, calcium oxide, sodium oxide, copper (II) hydroxide, zinc hydroxide, magnesium hydroxide, lead (II) hydroxide, calcium hydroxide and sodium hydroxide. They react in a similar way, giving similar products.
How do acids react with bases?
Materials and substances required
- Sulphuric (VI) acid (dilute)
- Sodium hydroxide (dilute)
- Phenolphthalein indicator, dropper
- Watch glass, beaker, water, tripod stand, wire gauze, and Bunsen burner
pH scale (jansanconsulting.com)
Open the video below, reaction of acids with bases.
Keenly observe what happens to the reacting mixture, and answer the questions that follow (The reaction involves dilute sulphuric acid to represent acids and sodium hydroxide to represent bases).
Questions 3.5(a)
- What is the colour of phenolphthalein in sodium hydroxide solution?
- What does this confirm about sodium hydroxide?
- What is the final colour of phenolphthalein in the reacting mixture?
- What does this show about the change in pH?
- One of the products of this reaction is water. Name the other product.
- What would be observed on the watch glass if the water in the product is evaporated to dryness? Hint: Check the pictures of Common Chemistry Laboratory Chemicals, under sodium and its compounds.
- Write a word equation for the reaction between sodium hydroxide and sulphuric acid solutions.
- From the final colour of phenolphthalein, what would you call this reaction? Hint: The products, which include water, are neither acidic nor basic.
Answers to Questions 3.5(a)
This reaction, between acid and base, produces salt and water only.
Also, the acid and base neutralize each other. It is therefore called neutralization reaction. Neutralization is the reaction between
an acid and a base to produce salt and water only.
Questions 3.5(b)
- Complete the following word equations
- Copper (II) oxide + Hydrochloric acid
- Zinc oxide + Sulphuric (VI) acid
- Magnesium oxide + Nitric (V) acid
- Lead (II) oxide + Nitric (V) acid
- Calcium oxide + Hydrochloric acid
- Sodium oxide + Sulphuric (VI) acid
- Copper (II) hydroxide + Nitric (V) acid
- Zinc hydroxide + Nitric (V) acid
- Magnesium hydroxide + Hydrochloric acid
- Calcium hydroxide + Nitric (V) acid
- From the table of Common Chemistry Laboratory Chemicals, under copper and its compounds, state what would be observed when the solutions obtained in 1(a) and (g) are crystallized.
Answers to Questions 3.5(b)
For curiosity
Since phenolphthalein is colourless in acidic and neutral solutions, was the product really neutral or acidic? Are we sure neutralization occurred?
Well, the pH was initially basic (pink colour) and even if the final pH was acidic, due to excess acid added, the reacting mixed must been neutral (pH=7) before it became acidic. Therefore neutralization occurred. Human blood has a pH of 7.4.
At home
Some metal hydroxides such as aluminium hydroxide and magnesium hydroxide are used to neutralize excess acid in the stomach.