1. SEKOLAH MENENGAH
KEBANGSAAN
SERI BINTANG SELATAN
SEKOLAH KLUSTER
KECEMERLANGAN
ACIDS & ALKALI
NAME : : NURUL SHAZATUL SYAHMI
BINTI MOHD. NASIR
CLASS : 2 DAMAR
TEACHER’S NAME : PUAN NORREHAN BINTI
NAWAWI

2. INTRODUCTION
ACIDS AND ALKALI IN OUR BODY
In humans and many other animals, hydrochloric acid is a part of the gastric acid secreted
within the stomach to converting the inactive pro-enzyme. Citric acid plays a role in one
famous stomach remedy, or antacid. Antacids are more generally associated with alkaline
substances, used for their ability to neutralize stomach acid. It is also used in the production
of hair rinses and low-pH shampoos and toothpastes. Amino acids combine to make up
proteins, one of the principal components in human muscles, skin, and hair.
HISTORY OF ACIDS AND ALKALI
The concepts of acidity came from the ancient Greeks who defined “sour-tasting”
substances as oxein, which mutated into the Latin word for vinegar, acetum, which became
anglicized to “acid”. Acid substances were eventually found not only to taste sour, but also
to change the color of litmus paper and corrode metals. The concept of alkali - one of the
first people who talked about the alkali was the great "Sleeping Prophet," Edgar Cayce. He
always referred to body detoxification with herbs, colonics, fasting, massage, steam baths
and diet modification with the aim of alkalizing the body.
INDICATOR THAT USES TO SHOW ACID OR ALKALI IN A
SUBSTANCE
• Litmus
• Phenolphthalein
• Methyl Orange
• Bromophenol Blue
• Universal Indicator

3. The pH scale
The Strength of an Acid
The strength of an acid or alkali is shown using a scale of numbers called the pH scale. The
numbers go from 0-14.
An acidic solution has a pH number less than 7
An alkaline solution has a pH number greater than 7
A neutral solution has a pH number of exactly 7.
Universal indicator will change from green to a different colour depending on the pH of the
solution you place it in.

4. ACID
Definition of acid
An acid in common usage is a substance that tastes sour, reacts with metals and carbonates,
turns blue litmus paper red, and has a pH less than 7.0 in its standard state.
Examples include acetic acid (in vinegar) and sulfuric acid (used in car batteries). Acids
can occur in solid, liquid or gaseous form, depending on the temperature. They can exist as
pure substances or in solution. Chemicals or substances having the property of an acid are
said to be acidic.
Properties of acids
1. They are liquids .
2. They are solutions of compounds in water.
3. If concentrated they can be corrosive
4. Acids taste sour (for example, vinegar).
5. Turn blue litmus paper red
6. Usually react with metals to form salts.
7. Acids contain hydrogen ions.
8. Turn universal indicator from green to red, and have a ph less than 7.
Uses of acids
There are numerous uses for acids.
Acids are often used to remove rust and other corrosion from metals in a process known as
pickling. They may be used as an electrolyte in a wet cell battery, such as sulfuric acid in a
car battery. A wasp sting is alkali. It may be neutralized with a weak acid (lemon juice or
vinegar).
Some common acids used in your laboratories at school will be:
1. Hydrochloric acid, HCl(aq)
2. Nitric acid, HNO3(aq)
3. Sulphuric acid, H2SO4(aq)
Example of acids around us
-Milk (slightly acidic)
-Lemon juice, orange juice (citric acid)
-Soda
-Vinegar
-Distilled water
Pictures

5. ALKALI
Definition of alkali
An alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some
authors also define an alkali as a base that dissolves in water. A solution of a soluble base
has a pH greater than 7.
Properties of alkalis
1. They feel soapy to touch.
2. They are soluble bases.
3. Like acids, they can burn the skin.
4. They turn red litmus blue - this is how you test for an alkali!
5. Alkalis contain hydroxide ions (OH-).
6. They taste bitter.
7. Turns Universal Indicator from green to blue or purple.
Uses of alkaline
Sodium Hydroxide is used to make paper, detergents and soap.
Potassium Hydroxide is used in farming to make acidic soil more alkaline so that plants
will grow better in it.
Calcium Carbonate is used as a building material.
Magnesium Hydroxide is used to help with stomach aches or indigestion. It makes the
contents of a stomach less acidic
Some common alkalis used in laboratories at school will be:
1. Sodium hydroxide, NaOH(aq)
2. Ammonia, NH3NH4OH(aq)
3. Calcium hydroxide, Ca(OH)2(aq)
Example of alkali around us
Toothpaste contains a minimum amount of alkali to kill the acids off in the teeth .Other
household items contain alkali such as Black coffee and various oven cleaners.
• Bleach
• Bicabonate of Soda
• Washing Soda
• Powder
• Drain Cleaners
Pictures

6. Comparing acids and alkali
Similarities
• Corrosive
• Only shows it properties in the presence of water
difference
acid alkali

7. Properties of acid and alkali
pH 1 pH 2 pH 3
pH 3 pH 4 pH 5
pH5 pH 5 pH 6

8. pH 7 pH 8 pH 9
pH 10 pH 11 pH 12
pH 13 pH 14

9. Properties of acid and alkali
1
Properties of acid
and alkali
taste
Sour (acid) Bitter (alkali)
t Green leafy vegetables
• Lemon juice t Wild edibles
Fresh herbs
• Beer Grasses
• Soda Sprouts
• Vinegar Sea vegetables
Medicinal mushrooms

10. 2
Properties of acid
and alkali
Limus paper
• Red (acid) • Blue (alkali)
3 Properties of acid and
alkali
pH value
Acid Alkali
Less than 7 greater than 7

11. Reference
• Text book
- Choo Yan Tong , 2003 , Science Form 2 , Volume Two , Selangor
Darul Ehsan .
• Reference book
- Peter Ling Chee Chong , 2004 , Exploring Science Revised
Edition Form 2 , Selangor Darul Ehsan .
- Choo Yan Tong , 2006 , Latihan U Masteri Science Form 2 ,
Selangor Darul Ehsan .
• Internet
- http://www.google.ca/
- http://en.wikipedia.org/wiki/Wiki