Acids,Bases And Salt Notes
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| ACIDS BASES AND SALT NOTES |
Indicators:-There are many substances which show one characteristics property (colour,odour etc)in the acidic medium ,on a different property in basic medium such substances are called as acid-base indicators.Depending upon the property of the indicator we have the following two types of indicator.
1.Indicators showing different colours in acidic and basic medium.
2.Indicators giving different odours in acidic and basic medium.
Natural Indicators
| Indicators | Smell Colour in Acidic Solution | Smell Colour in basic Solution |
|---|---|---|
| Litmus | Red | Blue |
| Red Cabbage Leaf Extract | Red | Green |
| Turmeric | No Change | Red-Brown |
| Indicators | Smell Colour in Acidic Solution | Smell Colour in basic Solution |
|---|---|---|
| Phenolphthalein | Colourless | Pink |
| Methyl Orange | Red | Yellow |
OLFACTORY INDICATORS
| Indicators | Smell Colour in Acidic Solution | Smell Colour in basic Solution |
|---|---|---|
| Onion | Characteristics Smell | No Smell |
| Vanilla Essence | Retains Smell | No Smell |
| Clove Oil | Retains Smell | Loses Smell |
Source of Different Acid
1.Acetic Acid:- Vinegar etc.
2.Citric Acid:-Lemon, Orange etc.
3.Tartaric Acid:-Tamarind,Grapes etc
4.Ascorbic Acid:- All Citrus fruits
5.Latic Acid:-Milk,Yoghurt
6.Malic Acid:- Apple ,pears
7.Formic Acid:- Ant,Bee etc.
8.Amino acid :- Protein
Chemical properties of Acid
Arrhenius Acid:- The substance which release H+ ions in aqueous medium are called Arrhenius Acid.
Basicity of Acids :-
Basicity of an acid may be defined as the number of replaceable hydrogen atoms present in an acid which can release when dissolved in water or in aqueous solution.
Acids have been classified as Monobasic,Dibasic,Tribasic etc. Depending upon the number of replaceable hydrogen atoms present.
Chemical Reaction of Acid
Acids like dilute HCl and dilute H2SO4, react with certain metal like Zinc(Zn),Iron(Fe) etc.To form salts and evolves H2 gas.
Thus these acids or substances containing these kind of acids shield not be kept in metal containers.
Metal+Dilute Acid ----->Salt+Hydrogen gas
Test of H2 Gas:-
Hydrogen ignites in air,if hydrogen is present in a test tube a lighted splint held near it's mouth ignites with squeaky pop.
Reaction with Metal Carbonate and Hydrogen Carbonate:-
Limestone,chalk and marbles are different forms of Calcium Carbonate.
Acids reacts with metal Carbonates and hydrogen carbonate to produce their corresponding salt,carbon dioxide and water
Metal Carbonate/Metal Hydrogen Carbonate ------>Salt+CO2+H2O
Test of CO2 gas
When CO2 gas is passes through lime water,it turns milk due to formation of white precipate of CaCO3.
But If CO2 is passes in excess,milkiness disappears due to Formation of Ca(HCO3)2 which is soluble in water.
Reaction with metal oxides
Acids reacts with certain metal oxides (being basic in nature also called metal oxides) to form and salt and water.
Metal Oxide+Acid------->Salt+Water
Acid Rain
Rainfall made so acidic by atmospheric pollution that it causes environmental harm,chiefly to forests,lakes,plants,animals,human and historical monuments.
The main cause is the industrial burning of Coal and othe fossil fuels,the wastes gases from which contain Sulphur and nitrogen oxides which combine with atmospheric water to forms acid.
Bases:-Bases are those chemical substances which are bitter in taste soapy to touch and turns red litmus to blue.
Chemical Properties of Bases:-
Arrhesnius Concept of Base:- The substance which release OH- ions in aqueous medium is called Arrhesnius base.
Acidity of Bases:- Acidity of a base Mau be defined as the number of replaceable hydroxyl groups present in a base which it can release when dissolved in water or in aqueous solution as ions.
Chemical Properties of Bases:-
Reaction with metals:-
Strong bases reacts with active metals to produces hydrogen gas.Thus these bases should be kept in metal container.
Metal+ Base ———>Salt +Hydrogen
Zn+2NaOH ————> Na2ZnO2+H2
Al+NaOH———>NaAlO2;+H2
Reaction with non-metallic oxide:-
Bases reacts with non metallic oxides(being acidic in nature also called acidic oxides) to produce salt and water.
This reaction proves that non metallic oxides are acidic in nature.
Bases+Non metallic oxides——>Salt+Ca(OH)2+CO2——> CaCO3+H2O
pH Value of Acidic and Basic solution:-
pH refers to Potent of Hydronium Ion.
Formula of pH is -log10 (H+ )
Concentration of Hydronium Ion refers to no of mole of H+ ions present in per litre of Solution.
pH Scale
pH scale was firstly derived by SORENSEN.
It is a scale used for measuring hydrogen ion concentration.The p in pH stands for potenz which means power in German.
It has a value ranging from 0(very acidic) to 14(Very Alkali).pH is a number which indicates the acidic and basic nature of a solution ..
Higher the Hydronium Ion concentration present in the solution,lower is it s pH value.
if pH>7 solution is basic
If pH=7 solution in netural
if pH<7 solution is acidic
pH value of Different Substances
Battery 0
Stomach Acid 1
Lemon 2
Vinegar 3
Tomato 4
Coffe 5
Milk 6
Water 7
Blood 8
Baking Soda 9
Stomach Tablets 10
Ammonia Solution 11
Soap 12
Bleach 13
Drain Cleaner 14
Importance of pH in Everyday life
Plants and Animals are pH sensitive:-
Living organisms can survive only in a narrow range of pH change,our body works normally within a pH range of 7 to 7.8
When the pH of Rainwater goes below 5.6,it is called acid rain.When acid rain flows into the rivers,it lowers the pH of River water and makes the survival of aquatic life difficult.
pH of the Soil:-
Every type of plant require a specific pH range for healthy growth.Therefore the nature of soil known first by testing it's pH and then a particular crop is grown in it.
It is also suitable for selecting the fertiliser for a particular crop by knowing the pH of the Soil.
pH in Plants
Stinging hair of nettle leaves injects methanoic acid in the skin which causes buring pain.
It is cures by rubbing the affected area with the leaves of dock plant,which ofter grow beside the nettle plant.
pH in our Digestive System
HCl present in the stomach helps in digestion of Food.
During ingestion if the stomach produces too much acid,it causes pain and irritation.
To correct the disturbed pH range milk of magnesia (the mild base) is the hardest substance in the body. If pH inside the mouth decrease below 5.5(acidic) the decay of tooth enamel beings.
The bacteria present in the mouth degrades the sugar and the leftover food particles and produce acids and remains in the mouth after eating.
Salts
Salts are produced by the neutralisation reaction between acid and base.
Types of salts
Based on the type of acid and base used to form a salt it can be classified in three types
Neutral Salt:- Strong Acid+ Strong Base
Ex.NaCl
Acidic Salt :- Strong Acid+ Weak Base
Ex. CH4Cl
Basic Salts:- Weak Acid+ Strong Base
Ex.CH3COONa
Washing Soda:-
Sodium Carbonate is a white crystalline solid.its solution in water is alkaline in nature.(turns red litmus to blue)
It has the poverty remove dirt and grease from dirty clothes,this it is called washing soda.
Sodium Carbonate can be obtained by heating baking soda.The crystallization of Sodium Carbonate giving washing.It is also a basic salt.its chemical name is Sodium Carbonate Decahydrate and chemical formula Na2CO3.10H2O
Manufacturing of Washing Soda(Solvay Process)
1.When ammonical brine solution is passes through CO2 gas,it produces ammonical chloride and Sodium bicarbonate.
2.Sodium Bicarbonate on further heating produces anhydrous Sodium Carbonate,Carbon Dioxide and water vapour.
Uses of Washing Soda
1.It is used in glass,Soap and paper industries.
2.It is used for manufacture of sodium compound like borax.
3.It is used as a cleansing agent in house and laundries.
Baking Soda(Sodium Hydrogen Carbonate NaHCO3)
- The soda commonly used in the kitchen for making tasty crispy pakoras in the baking soda.
- It is mild non corrosive base.it is major constituent of baking powder.Sometimes,it is added for fast cooking.
- Chemically it is sodium bicarbonate.Itis produced by using sodium chloride as one of the raw material.
Uses of Baking soda
- For making baking powder,which is a mixture of baking Soda(Sodium Hydrogen Carbonate ) and a mild edible acid such as tartaric acid.Whrn baking Powder is heated or mixed in water the following reaction takes place.
- Sodium Hydrogen Carbonate is also an ingredient of antacid.Being Alkaline,it neutralises excess acid in stomach and provide releif.
- It is also used in Soda Acid fire extinguisher.
Bleaching Powder(Calcium Oxychloride CaOCl2)
- It is produced by the action of chlorine on dry slaked lime.
- It is represented as CaOCl2,through the actual composition is quite complex.
- It is prepared in HASENCLEVER plant.
Uses of Bleaching Powder:-
1.For bleaching cotton and linen in the textile industry,for bleaching wood pulp in paper factories and for bleaching washed clothes in laundry.
2.As an oxiding agent used in many chemical industries.
3.For Disinfecting drinking water to make it free of germs.
Plaster of Paris(Calcium Sulphate Hemihydrate CaSO4.1/2H20 )
- It is obtained by heating gypsum(CaSO4.2H2O) at 373K.
- At this temperature gypsum loses water molecules and forms plaster of Paris.
Uses of plaster of Paris
1.It is used by doctors for joining the fractured bone at eight position.i.e, for making plaster to support fractured bones.
2.It is also used making decorative pieces for design on ceiling.
Caustic Soda
- It is chemically known as Sodium Hydroxide.
- It is a strong base with a chemical formula.
- It is monoacidic base.
- It is prepared by Chlor Alkali process.
Preparation of Caustic Soda:-
When electricity is passes through aqueous solution of Sodium Chloride(Called Brine),it composed to Form Sodium Hydroxide,this process is called Chlor Alkali.
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