Post on 29-Dec-2015
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