ACID AND BASES ACID AND BASES THE STRENGTH OF ACIDS AND ALKALIS CONCENTRATION OF ACIDS AND ALKALIS NEUTRALISATION

ACID AND BASESACIDSExamples: (Chemical formulae of the acids ) HCl, HNO3, H2SO4, CH3COOH

ii. When acids are dissolved in water, hydrogen atom are released as hydrogen ions, H+

DEFINITION OF AN ACIDAn acid is a chemical substance whichionises in water to produce hydrogen ions,H+

Hydrogen chloride molecule, HCl dissolves in water and ionises to produce a hydrogen ion, H+ HCl H+ + Cl-The hydrogen ion combines with a water molecule, to form a hydroxonium ion, H3O+ H+ + H2O H3O+

Classification of acid based on its basicityMonoprotic acid : HCl and HNO3Diprotic acid : H2SO4

Basicity of an acid : The maximum number of hydrogen ions thatis produced when one molecule of the acidionises in water

Bases and alkalis

A base is a substance that reacts with an acid to form a salt and water

Examples of bases : All metal oxides and metal hydroxide CuO, MgO, Na2O- Cu(OH)2, Mg(OH)2, NaOH

Definition of a baseA base is a chemical substance which ionises in water to produce hydroxide ion, OH-

A base that dissolves in water is called anAlkali : NaOH, KOH, Na2O, K2O, Ca(OH)2 Ammonia solution, NH3(aq)

NaOH dissolves in water and releases its hydroxide ion,OH-

NaOH Na+ + OH-Ammonia molecule, NH3 dissolves in water to produce a hydroxide ion, OH-

NH3 + H2O NH4+ + OH-

Uses of acids, bases and alkaliLaboratary reagentsManufacture and preserve food-benzoic acid, carbonic acid, ethanoic acid, ascorbic acidMaking medicines-magnesium hydroxide(toothpaste) and Aluminium hydroxide (gastric pills)Producing detergents, soaps and shampoo ( sulphuric acid, hyrochloric acid, sodium hydroxide),

Role of water and the properties of acidsAn acid only shows its acidic properties when dissolved in water, - Without water : acid exists as molecules , no H+ ions present, - In water : acid ionises to produce hydrogen ions, H+

Role of water and the properties of alkalisAn alkali only shows its alkaline properties when dissolved in water, - Without water : no free mobile OH- ions present, - In water : alkali ionises to produce hydroxide ions, OH-

The role of water in showing the properties of acids and alkalisHydrogen ions ,H+ are responsible for the acidic properties.Hydroxide ions, OH- are responsible for the alkaline properties.

Water is essential for an acid to ionise to produce hydrogen ions, H+ Water helps a base to ionise to produce hydroxide ion, OH-

CHEMICAL PROPERTIES OF ACIDSAcids react with bases/alkali to form salts and water.Acids react with reactive metals to produce salts and hydrogen gas, H2.Acids react with carbonates to produce salt, water and carbon dioxide, CO2

Reaction of an acid with basesSulphuric acid + copper(II) oxide copper(II) sulphate + water H2SO4 + CuO CuSO4 + H2O

Reaction of acid with reactive metalHydrochloric acid + zinc zinc chloride + hydrogen

2HCl + Zn ZnCl2 + H2

Reaction of an acid with metal carbonatesNitric acid + calcium carbonate calcium nitrate + water + carbon dioxide

HNO3 + CaCO3 Ca(NO3)2 + H2O + CO2

Experiment todayReaction of acids investigate the chemical properties.

Get the salt ( solid/crystal)

CHEMICAL PROPERTIES OF ALKALISAlkalis react with acids to form salts and water.A mixture of an alkali and an ammonium salt is heated ammonia gas, NH3 produced.Adding and alkali ( OH- ion) to most cation solutions (metal ions solutions) will give a precipitate of metal hydroxide