ACID

Acid is a substance which produce Hydrogen ion (H⁺ ) as the only positive ion when it is dissolved in water.

Example of Acid :

Chemical Formula	Naming of Acid	Ion Present
HNO₃	Nitric Acid	H⁺, NO₃^-
HCl	Hydrochloric Acid	H⁺ , Cl^-
H₂SO₄	Sulfuric Acid	2H⁺ , SO₄^2-
H₂CO₃	Carbonic Acid	2H⁺, CO₃^2-
H₃PO₄	Phosphoric Acid	3H⁺, PO₄^3-

All acid contain hydrogen but not all substance that contain hydrogen are acids

Properties of Acid

Acid is a substance that produce H⁺ ion
Acid has sour taste
Some of Acid are corrosive Exp : HNO₃
Acid dissolve in water to form solution which conduct electricity
Acid has pH lower than 7
Acid its turn litmus blue into red

Test For An Acids

Blue litmus paper. Aqueous solutions of acid turn blue litmus paper to red
Red litmus paper. Aqueous solution will not change the color of red litmus paper.
Universal indicator paper (white color). Aqueous solutions turn universal indicator orange to red.

3 Type Reaction of Acid

Acid React with Metal Produce Salt and Hydrogen

Rx : 2HCl_(aq) +2Na_(s)→ 2NaCl_(aq) + H_2(g)
The metal that can react with acid is the more reactive metal, for the least reactive metal would not react with the acid Example : Cu and Pb. When acid react with metal produce Hydrogen gas, to get the evidence that reaction acid produce Hydrogen gas. We can do light splint test. If we put the wooden light splint into the mouth of the test, the "pop" sound is heard.

Picture 1. Test for Hydrogen gas

Acid React with Base / Alkali Produce Salt and Water

Rx : HCl_(aq) + NaOH _(s) → NaCl_(aq) + H₂O_(l)

Reaction between Acid and Alkali or Base to produce salt and water are called neutralization reaction

Acid React with Metal Carbonate Produce Salt, Water, and Carbon dioxide

Rx: Na₂CO₃ _(aq)+ 2HCl _(aq)→ 2NaCl_(aq) + H₂O_(l) + CO_{2 (g)}

The gas produce in this reaction is carbon dioxide. To testing the present of carbon dioxide. We can use the lime water. The result of observation the reaction is fizzing or effervescence, white precipitation is formed and the solution getting milky cloudy

Picture 2. Test for Carbon dioxide gas

Classification of Acid

Strong Acid is the substance of acid that dissociated completely or fully on the water. Strong Acid mostly from mineral of Acid such as hydrochloric acid, Sulfuric acid

Example : HCl _(aq) → H⁺ _(aq) + Cl^-_(aq)

Weak Acid is the substance of acid that dissociated partially on the water. Weak acid mostly from organic acid such as carbonic acid or ethanoic acid

Example :

What is a salt ? A salt is a compound obtained when the hydrogen of an acid is partially or completely replaced by metal or an ammonium ion.

Although most dillute acids react with most metal to give Hydrogen gas. There are certain exceptions to this rules.

Dilluted nitric acid, being an oxidising agent, react with metal to give nitrogen dioxide (poisonous brown gas)
when copper, or silver comes into contact with dillute acid no bubbles of hydrogen gas are given off. Unreacted metal do not react with dilluted acids
Lead does not dissolve in dillute HCl and H₂SO₄

BASE OR ALKALI

Base is the substance that cannot dissolved in water. Example : Fe₂O₃

Alkali is the substance that can dissolved in water . Example: NaOH

Base or Alkali is the substance which produce hydroxide ion (OH^-) as the only negative ion when its dissolved in water

Chemical Formula	Naming of Base	Ion Present
NaOH	Sodium Hydroxide	Na⁺, OH^-
Mg(OH)₂	Magnesium Hydroxide	Mg²⁺ , OH^-
Na₂O	Sodium Oxide	2Na⁺ , O^2-
Fe(OH)₃	Iron (III) hydroxide	Fe³⁺, OH^-
NH₃	Ammonia	NH₃

Properties of Base or Alkali

Base or Alkali is a substance that produce OH^- ion
Alkali has bitter taste, feel soapy or slippery
Some of Alkali are corrosive
Alkali dissolve in water and conduct electricity
Alkali has pH greater than 7
Alkali its turn litmus red into blue and universal indicator blue or violet
When heated, All alkalis (except Ammonia) react with ammonium salt to produce Ammonia, a pungent gas

2 Type Reaction of Alkali

Alkali React with Acid Produce Salt and Water

Rx : HCl_(aq) + NaOH _(s) → NaCl_(aq) + H₂O_(l)

Reaction between Acid and Alkali or Base to produce salt and water are called neutralization reaction

Alkali react with Ammonium Salt to Produce Salt, Water and Ammonia

Rx : NaOH _(aq)+ NH₄Cl _(aq)→ NaCl_(aq) + H₂O_(l) + NH_{3 (g)}

The gas produce in this reaction is Ammonia. To testing the present of Ammonia. We can use the red litmus paper. The result of observation the litmus paper red its turn blue

Picture 3. Test for Ammonia gas

Classification of Alkali

Strong Alkali is the substance of acid that dissociated completely or fully on the water. Strong Alkali mostly from mineral of Base such as Sodium Hydroxide, Magnesium Oxide

Example : NaOH _(aq) → Na⁺ _(aq) + OH^-_(aq)

Weak Alkali is the substance of acid that dissociated partially on the water.

Example :

PH Scales

Chemist use an indicator to measure the pH of solution. An indicator is a compound that has one color in acidic solution and another color in alkaline solution.