Free Chemistry Lesson Note SS 3

Free Chemistry Lesson Note SS 3

This Chemistry Lesson Note was pulled from our book ( LESSON NOTE ON SS3 CHEMISTRY MS-WORD); Compiled to serve as reference material to help teachers draw out their lesson plan easier, saving you valuable time to focus on the core job of teaching.

The Chemisry Lesson notes are based on the current NERDC curriculum (UBE compliant)

This Chemistry Lesson Note Covers The Following Topics

1. 1. ALKANOIC ACIDS
   2. ALKANOATES
   3. FATS AND OILS
   4. AMINO ACIDS
   5. NATURAL AND SYNTHETIC POLYMERS
   6. CARBOHYDRATES
   7. METALS AND THEIR COMPOUNDS
   8. CALCIUM AND ALUMINIUM
   9. TIN AND COPPER
   10. IRON

   WEEK 1

   Alkanoic Acids

   Alkanoic acids are also known as carboxylic acids. A carboxylic acid can he identified from the carboxyl functional group and the ‘-oic’ name ending.

   General formula of carboxylic (alkanoic acids) : C_nH_2n+1COOH or R-COOH

   Examples of Carboxylic (Alkanoic) Acids

   Formula	longest carbon chain	C-C single bonds	functional group	Name	occurrence
   HCOOH	C1 : meth	-an-	-COOH (oic acid)	methanoic acid (formic acid)	ants
   CH3COOH	C2 : eth	-an-	-COOH (oic acid)	ethanoic acid (acetic acid)	vinegar
   C2H5COOH	C3 : prop	-an-	-COOH (oic acid)	propanoic acid (propionic acid)	dairy products
   C3H7COOH	C4 : but	-an-	-COOH (oic acid)	butanoic acid (butyric acid)	rancid butter
   C4H9COOH	C5 : pent	-an-	-COOH (oic acid)	pentanoic acid (valeric acid)	valerian root

   Structural Examples  of carboxylic acids

    

   Nomenclature (Naming Alkanoic Acids)

   Alkanoic acids are named as follows:

   • The number of carbon atoms in the longest carbon atom chain is noted
   • The corresponding alkane is then named
   • Finally, the name of this corresponding alkane is modified by removing the ane and replacing it with alkanoic acid

   For example:

   thylpentanoic acid     ,

   2-ethylpentanoic acid      ,

   benzoic acid

   Preparation of ethanoic acid

   The Complete Oxidation of Ethanol to Ethanoic Acid by acidified sodium heptaoxochromate(VI) solution. Ethanol undergoes oxidation first to ethanal and then to ethanoic acid.

   The reaction of sodium dichromate(VI) solution with ethanol gives a carboxylic acid, ethanoic acid, a dilute solution of which is sold as vinegar.

   Ethanoic acid can also be prepared by

   distilling anhydrous sodium ethanoate, CH₃COONa with concentrated H₂SO₄

   or boiling methyl cyanide CH₃CN with an acid

   CH₃COONa_(aq)+ H₂SO_4(aq)  → CH₃COOH_(g) + NaHSO_{4 (aq)}

   CH₃CN_(aq) + HCl_(aq) → CH₃COOH_(g) + NH₄Cl_(aq)

    

   Physical Properties

   Ethanoic acid is usually a colourless liquid with a characteristics sharp and pungent smell

   It is soluble in water and a dilute solution has the usual sour taste of acid

   It has a boiling point of 118⁰C

   Pure anhydrous ethanoic acid freezes into ice-like crystals at temperature below 17⁰C

   It turns blue litmus paper red

   Dilute solution has a sour taste

    

   Chemical Properties of Carboxylic (Alkanoic) Acids

   Carboxylic (alkanoic) acids are weak acids, the acid dissociation constant, K_a, is small.

   Soluble carboxylic (alkanoic) acids dissociate slightly in water.

   Neutralization Reactions

   Neutralization: acid + base → salt + water

   Carboxylic (alkanoic) acid + base → salt (metal alkanoate) + water

   RCOOH + MOH → RCOO^–M⁺ + H₂O

   e.g. CH₃COOH + NaOH → CH₃COO^–Na⁺ + H₂O

   Ethanoic acid + sodium hydroxide → sodium ethanoate + water

   Soluble salts of long-chain (fatty) acids are soaps

   e.g. C₁₇H₃₅COOH + NaOH → C₁₇H₃₅COO^–Na⁺ + H₂O

   Stearic acid + sodium hydroxide → sodium stearate + water

   Reaction with Carbonates

   acid + carbonate → salt + carbon dioxide gas + water

   Carboxylic (alkanoic) acid + metal carbonate → metal alkanoate + carbon dioxide + water

   e.g. 2CH₃COOH + Na₂CO₃ → 2CH₃COO^–Na⁺ + CO₂ + H₂O

   Ethanoic acid + sodium carbonate → sodium ethanoate + carbon dioxide + water

   e.g. CH₃COOH + NaHCO₃ → CH₃COO^–Na⁺ + CO₂ + H₂O

   Ethanoic acid + sodium bicarbonate → sodium ethanoate + carbon dioxide + water

   Reaction with Active Metals

   Acid + metal → salt + hydrogen gas

   Carboxylic (alkanoic) acid + metal → metal alkanoate + hydrogen

   e.g. 2CH₃COOH + 2Na(s) → 2CH₃COO^–Na⁺ + H_2(g)

   Ethanoic acid + sodium → sodium ethanoate + hydrogen

   Esterification Reactions

   Esters are produced in a condensation reaction between a carboxylic (alkanoic) acid and an alkanol (alcohol).

   This is known as an esterification reaction.

   carboxylic (alkanoic) acid + alkanol (alcohol) ester + water

   e.g. 2CH₃COOH + CH₃OH CH₃COOCH₃ + H₂O

   Ethanoic acid + methanol methyl ethanoate + water

    

   Uses

   It can be used as a solvent

   It is used in food industries as vinegar for preserving and flavouring food

   It is used In the manufacture of cellulose ethanoate which is used for making synthetic fibres, such as rayon

   It is used in making compounds like ethyl ethanoate, ethanoic anhydride (used in aspirin), cellulose ethanoate (used for packing), propanone etc

    

   Assessment

   Ethanoic acid is usually a colourless liquid with a characteristics sharp and ……. smell
   a. pungent
   b. annoying
   c. foul
   d. dirty

   Esters are produced in a condensation reaction between a carboxylic (alkanoic) acid and an alkanol (alcohol) known as …….
   a. Polymerization
   b. Esterification
   c. Dehydration
   d. Hydrolysis

   Ethanoic acid reacts with active metal to give off ……….. gas
   a. Oxygen
   b. Hydrogen
   c. Carbon
   d. OH

   Boiling point of Ethanoic acid is …….
   a. 117⁰C
   b. 119⁰C
   c. 118⁰C
   d. 120⁰C

   It is used in food industries as vinegar for preserving and flavouring food. True/False

    

   Answers

   A

   B

   B

   C

   True

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