Acids and

AlkalisT. Sudarat Khampa

Acids• Latin word ‘acidua’ : sour• Has a sour test• Has a pH value less than 7• Has a corrosive nature• Turns blue litmus paper red• Reacts with reactive metals to produce

hydrogen gas.

exampleexample AcidSoft drink Carbonic acidTomato Salicylic acidBattery Sulfuric acidGrape Tartaric acid

Ant/Bee Formic acidVinegar Acetic acidLemon Citric acid Yoghurt Lactic acidApple Malic acid

Orange Citric acid

Identifying the property of acidprocedure observation inference

Lemon tested with tongue sour test Acid test sour

- Dipped pH paper to dilute hydrochloric acid -Compare with color chart

pH value of 2 Acid has pH value less

than 7

Drop concentrated hydrochloric acid into a filter paper

It has hole in it.

Acid has corrosive

Identifying the property of acidprocedure observation inference

- Dipped red and blue litmus papers to dilute hydrochloric acid

blue litmus paper red

Acid turns blue litmus paper red

- placed magnesium ribbon in hydrochloric acid - test gas with a lighted spinter.

Gas give out a squeaky ‘pop’

Acid react magnecium to produce

hydrogen gas.

Alkali• Has bitter test• Has a pH value greater than 7• Terns red litmus paper blue• Has a soapy feel• Has corrosive nature• Reacts amonium salts to release ammonia

when heated.

example• Bleach• Oven /Glass cleaners• Detergent• Soap• Some Shampoo • Ammonium solution• Sodium hydroxide solution• Potassium hydroxide solution

In the laboratory

In your life

Identifying the property of alkali

procedure observation inferenceTouched dilute sodium hydroxide solution

It fell soapy and slippery

Alkali has soapy feel

- Dipped pH paper to sodium hydroxide solution-Compare with color chart

pH value of 10 Acid has pH value more

than 7

Identifying the property of alkali

procedure observation inferenceDrop concentrated sodium hydroxide into a filter paper

It has hole in it.

Alkali has corrosive

- Dipped red and blue litmus papers to dilute sodium hydroxide

red litmus paper turns

blue

Alkali turns red litmus paper blue

pH Indicators

• pH scale

pH Indicators• Change color when dipped in acids or alkalis

pH Indicators• Universal indicator

Uses of acids

• Citric acid : give a sour test to food and drinks : as a polishing agent for metals

• Tartaric acid : flavoring food and drinks : produce fruit/health salts

• Benzoic acid : preservative in food ; sauces

Uses of acids•Ascorbic acid : increase body resistance and (vitamin C) prevent scurvy

• Formic acid : coagulate latex

• Acetic acid : used as Vinegar : preservative in food ; pickles : to produce paints, plastics,

rayon

Uses of acids• Sulfuric acid : used in car battery and fire extinguishers

• Hydrochloric acid : clean metals : cleansing agent in toilet cleaners

• Nitric acid : to produce fertilizers, dye, explosive

Uses of alkalis

• Sodium hydroxide : to produce soap, detergent, plastic, rayon

• Calcium hydroxide : to produce cement, mortar, soda lime, glass

Uses of alkalis

• Amonium : - prevent coagulation of latex - glass cleaning agent - produce nitric acid and

fertilizer

• Magnesium hydroxide : produce medicine; - antacids - magnesia milk

- Epsom salt