Chemistry acid and bases

Acids

A proton donator

Acids properties

-sour

-ph less that 7 (1 is strongest, 6 is weakest)

-turn blue litmus paper red

Weak acids

Partially ionises in water to give H+ ions. ethanoic acid CH3COOH

Strong acids

Ionises fully in water to give H+ protons . Hcl (hydrochloric acid) H2SO4 ( sulfuric acid), HNO3 (nitric acid)

Monoprotic acids

Donate one proton per molecule in water

Diprotic acids

Donate 2 protons per molecule in water

Acid + base =

Salt and water . This reaction is also called neutralisation

Acid + carbonate

Salt + water + carbon dioxide

To test for carbon dioxide

Limewater is used. A white precipitate will be formed in limewater

Acid + metal

Salt + hydrogen gas

to test for hydrogen

Lighted splint test . Splint will extinguish and a pop sound would be heard

Bases

Metal oxides or a metal hydroxide that reacts with acid to form a salt and water only

Alkalis

Soluble base which dissolves to produce hydroxide ions in aqueous solution

Strong alkalis

Potassium hydroxide, calcium hydroxide, sodium hydroxide

Weak alkalis

NH3(ammonia)

Properties of alkali

-turn red litmus paper blue

-bitter

Ph scale

1-6: acids (strongest acid is 1 , weakest acid is 6)

7: pure water

8-14 ( 8 is least basic , 14 is most basic

How can ph be measured

Universal indicator, litmus paper, phenolphthalein, methyl orange

Universal indicator

0-2: red

3-4: orange

4-6:yellow

7:pale green

8-11: green-blue

12-14: violet

Litmus

Turns red when reacting with acid

Turns blue when reacting with alkali

Phenolphthalein

Acidic : colourless

Neutral : colourless

Alkaline : pink

Methyl orange

Ph less than 3.5: red

Neutral :yellow

Alkaline: yellow

Oxides

A compound of oxygen and another element

Basic oxides

React with acids only to form salt and water Eg. MgO , Na2O, CuO

Acidic oxides

Acceptor of hydroxide ions / react with base to form salt and water (non metal and oxygen eg. SO2, CO2)

Salt

Ionic compound formed by reacting acids with metals carbonates bases or alkalis

Cations

Positive ions

Anions

Negative ions

Soluble salts

SODIUM,POTASSIUM, AMMONIUM (group1)

NITRATE

InSoluble chlorides

• Most are soluble except lead chloride and silver chloride

Insoluble sulfates

Calcium sulfate, lead sulfate, barium sulfate, rest is soluble

Soluble carbonate/oxides/hydroxides

-mostly insoluble except sodium carbonate , potassium carbonate and ammonium carbonate +group 1 salts

Amphoteric oxide

React with both acid and base (metal and oxygen eg. ZnO,Al2O3, PbO)

Neutral oxides

Don not react with base or acid eg.CO, NO, H2pO