JSS 2: ACIDS, BASES AND SALTS

-
                                 ACIDS
An acid is a substance that produces hydrogen ions (H⁺) when dissolved in water.
                        Types of acids
The two types of acids are:
I. Organic acids
II. Inorganic acids
Organic acids occur naturally in plants and animals.
Inorganic acids are called mineral acids, since they are produced from mineral ores. They are man- made.
Examples of inorganic acids are:
1. Hydrochloric acid (HCl)
2. Trioxonitrate(V) acid (HNO₃)
3. Sulphuric acid (H₂SO₄) etc
                  Properties of Acids
1.  Acids have sour taste.
2.  Acids turn blue litmus paper red.
3. Acids react with metals to produce hydrogen gas.
4. They conduct electricity in solution.
5. They have pH values less than 7.
                   Uses of Acids
1. Acids are used for food preservation (e.g. acetic acid).
2. Manufacture of fertilisers.
3. Production of medicines.
4. Cleaning metals.
5. In the production of salts
       
                              BASES
Bases are substances that react with acids to form salt and water.
They are oxides or hydroxides of metals. Some bases are soluble in water while some are not soluble in water.
                             Alkalis
 Alkalis are bases that are soluble in water to produce hydroxide ions (OH⁻).
All alkalis are bases, but not all bases are alkalis.
Examples of bases that are soluble in water (alkalis) include:
1. Sodium hydroxide (NaOH)
2. Potassium hydroxide (KOH)
3. Calcium hydroxide, Ca(OH)₂ 
4. Magnesium hydroxide, Mg(OH)₂
5. Ammonium hydroxide (NH₄OH)
Examples of bases that are not soluble in water include:
1. Sodium oxide (Na₂O)
2. Copper(II) oxide (CuO)
3. Iron(II) oxide (FeO)
4. Iron(III) oxide (Fe₂O₃)
5. Zinc oxide (ZnO)
6. Lead(II) oxide (PbO) etc
          Properties of Bases
1. Bases have  bitter taste e.g. Lime water
2. They are slippery or soapy feel.
3. They turn red litmus paper blue.
4. They conduct electricity in solution.
5. They have pH values greater than 7.

              Uses of Bases
1. Use in making soap and detergents.
2. Used in neutralising acids.
3. For treating acidic soil.
4. For manufacturing paper and textiles.

                             SALTS
A salt is a compound formed when an acid reacts with a base.
               Neutralisation reaction
A neutralisation reaction is a chemical reaction between an acid and a base to produce salt and water.
General Equation:
Acid + Base (Alkali) → Salt + Water
Examples of Neutralisation Reactions:
1. HCl + NaOH → NaCl + H₂O
2. H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O
3. 2HNO₃ + Ca(OH)₂ → Ca(NO₃)₂ + 2H₂O etc.
                    Types of salts
1. Normal (Neutral) salts
2. Acid salts
3. Basic salts
4. Double salts
5. Complex salts
6. Hydrated salts
                 Normal salts
Normal salts are salts formed when all the hydrogen ions (H⁺) in an acid are completely replaced by a metal or ammonium ion during neutralisation.
HCl + NaOH → NaCl + H₂O
Examples:
I. Sodium chloride or Table salt (NaCl)
II. Calcium carbonate (CaCO₃)
III. Copper(II) sulphate (CuSO₄)
IV. Ammonium sulphate, (NH₄)₂SO₄
V. Potassium nitrate (KNO₃)
VI. Sodium sulphate (Na₂SO₄) etc.
                        
                      Acid salts
These are salts formed when only some of the hydrogen ions in an acid are replaced by a metal ion. They still contain hydrogen.
H₂CO₃ + NaOH → NaHCO₃ + H₂O
Examples: Sodium hydrogen carbonate (NaHCO₃), Sodium hydrogen sulphate (NaHSO₄)
                       Basic salts
These are salts formed when a base is partially neutralised by an acid. They contain hydroxide (OH⁻) groups.
Example: Copper(II)hydroxychloride
equation:
Cu(OH)₂ + HCl → Cu(OH)Cl + H₂O
                    
                    Double salts
Double salts are formed when two simple salts crystallise together in a fixed proportion.
Example: Potash alum, KAl(SO₄)₂·12H₂O
Equation:
K₂SO₄ + Al₂(SO₄)₃ + 24H₂O → 2KAl(SO₄)₂·12H₂O
                   Complex salts 
Complex salts contain complex ions consisting of a central metal ion surrounded by other ions or molecules.
Example: Potassium ferrocyanide, K₄[Fe(CN)₆]
Equation:
Fe²⁺ + 6CN⁻ → [Fe(CN)₆]⁴⁻
                 Hydrated salts
Hydrated salts are salts that contain water of crystallisation.
Water of Crystallisation: Is the definite amount of water molecules chemically combined within the crystal structure of a salt.
Examples of hydrated salts: 
1. Copper(II) sulphate pentahydrate
CuSO₄·5H₂O
2. Magnesium sulphate heptahydrate (Epsom salt), MgSO₄·7H₂O
3. Washing soda, Na₂CO₃·10H₂O
4. Gypsum, CaSO₄·2H₂O
                Properties of Salts
1. They are usually crystalline solids.
2. Most salts dissolve in water.
3. They can conduct electricity when molten or in solution.
                     Uses of Salts
1. For cooking and food preservation.
2. For producing fertilisers used in agriculture.
3. Salt is present in cement used for Construction
4. Salt is used in medicine e.g. Sodium chloride (table salt) used in saline solution for treating dehydration, cleaning wounds, and administering intravenous (IV) fluids.
5. For water treatment.

Comments

Post a Comment

Popular posts from this blog

SSS 1: ATOMIC STRUCTURE

-
Image
                              Atom An atom is the smallest particle of an element which can take part in a chemical reaction.                 Components of an atom An atom has two main parts: I. The nucleus (made of proton and neutron) II. The shells (electrons) which surrounds the nucleus at definite distance.                   Structure of an atom                    Sub-particles of an atom An atom is made up of three sub-particles namely: I. Proton II. Electron III. Neutron  Proton and neutron are the nuclear particles found in the nucleus, while the electrons are in constant and continuous motion in the shells at various energy levels around the nucleus.         Characteristics of the sub-particles  ...
Read more

SSS 1: CURRICULUM

-
Image
     FIRST TERM   WEEK 1: INTRODUCTION TO CHEMISTRY WEEK 2: NATURE OF MATTER WEEK 3: SEPARATION TECHNIQUES WEEK 4: PARTICULATE NATURE OF MATTER (1). WEEK 5: PARTICULATE NATURE OF MATTER (2) WEEK 6: C.A WEEK 7: ATOMIC STRUCTURE  WEEK 8: CHEMICAL COMBINATION (BONDING) WEEK 9: KINETIC THEORY OF MATTER (I) WEEK 10: HYDROCARBONS  WEEK 11: REVISION  WEEK 12: EXAMINATION  WEEK 13: RESULT/CLOSING                SECOND TERM  WEEK 1: KINETIC THEORY OF MATTER (II) WEEK 2: CARBON AND ITS COMPOUNDS (I) WEEK 3: CARBON AND ITS COMPOUNDS (II) WEEK 4: ACIDS WEEK 5: BASES AND ALKALIS WEEK 6: FIRST C.A WEEK 7: SALTS WEEK 8: PH AND POH WEEK 9: ORGANIC CHEMISTRY (I) WEEK 10: REVISION WEEK 11: EXAMINATION  WEEK 12: EXAMINATION  WEEK 13: RESULT/CLOSING                 THIRD TERM  WEEK 1: INDUSTRIAL CHEMISTRY WEEK 2: KINETIC THEORY OF MATTER (III) WEEK 3: ...
Read more

SSS 1: PARTICULATE NATURE OF MATTER (II)

-
Image
                Relative Atomic Mass The Relative Atomic Mass (RAM) of an element is the average mass of its atoms compared with one-twelfth (¹/₁₂) of the mass of one atom of carbon-12. The carbon-12 isotope (¹²C) is used as the standard for measuring atomic masses. Relative atomic mass of an element  = average mass of one atom of element     ¹/₁₂ × the mass one carbon -12 atom                     Relative Moleculer Mass Relative Molecular Mass ( RMM ), also called Molecular Weight, is the sum of the relative atomic masses (RAM) of all the atoms present in a molecule. The RMM has no unit (it’s a ratio). It shows how heavy a molecule is compared to ¹/₁₂  of the mass of one atom of carbon-12 (¹²C). Examples: 1. Water (H=1, O=16)  H₂O = (2 × H) + (1 × O)          = (2 × 1) + (16)        ...
Read more