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Chemistry (5070)

Characteristic Properties of Acids and Bases

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Characteristic Properties of Acids and Bases

The Characteristic Properties of Acids And Bases

There are two kinds of acids:

Organic Acid that is found in natural products such as plants and animals. They are sour to taste. These acids are relatively harmless. For example, they are not corrosive etc. Example of some common organic acids.



Inorganic Acids, Mineral Acids 

these acids are corrosive, they have a sour taste and turn blue litmus red. 

ACID is any substance that releases hydrogen ions, H+, in aqueous solution. Determining whether an acid is strong or not is the extent to which it ionizes in a solution. For example, HCl ionizes completely in a solution. Organic Acid such as ethanoic acid and like wise are weak acids as they partially ionize in solution. A reversible equation sign is used for acids to show that the ionization is weak and is reversible. 

Chemical Properties Of Acids

Reaction With Metals
Acids on reaction with many but not all metals release hydrogen gas. 
Reaction With Metal Carbonates
Acids on reaction with metal carbonates would release carbon dioxide gas.


Reaction With Bases
Acids react with bases to form salt and water.


Basicity Of An Acid

All acids release hydrogen ions in solution but not necessarily in the same number per molecule. 

Inorganic Acids

HCl is a monobasic acid as it only releases one hydrogen ion per molecule.
Sulfuric Acid is a dibasic acid as it releases two Hydrogen ion per molecule. 

Phosphorous acid is tribasic as it releases three hydrogen ions per molecule. 

Organic Acid
With the basicity of an acid it must be noted that not all hydrogen atoms would turn into hydrogen ions in a molecule. 
Ethanoic acid is monobasic Acid as it releases one Hydrogen ion per molecule. 
Ethane dioic Acid is a dibasic acid as it releases two Hydrogen ion per molecule. 

Uses Of Acid


Bases

A base is any substance that reacts with an acid to form a salt and water. 
The reaction looks as such
Acid + base à salt + water
This reaction is a neutralization reaction since the product at the end is neutral. the H+ and OH- ion from Acid and basic react to form water.
Dilute hydrochloric Acid reacts with sodium hydroxide, 
A base is a substance that contains hydroxide OH- + or oxide ions O2-

Bases And Alkalis

Bases are either metal oxides or metal hydroxides. Most metal Oxides are insoluble in water but the oxides of Group I and II metals react with water to form solutions of hydroxides. 

Group I metal hydroxides and a few Group II metal hydroxides are soluble in water and are called alkalis. 



Copper II Hydroxide and Aluminum Hydroxide are insoluble in water.

An alkali is a base which is soluble in water. Group I and II and ammonia solutions are alkalis. 

They all release OH- ions and the degree to which they do so determine whether the alkali is strong or weak.

Group I alkalis are strong, they ionize completely. 
Group II and aqueous ammonia are weak alkalis. 

Group I hydroxides release ammonia in reaction with ammonium salts, which can be detected by its smell and turns damp red litmus blue. 

Uses Of Bases



Acids, Basic And Amphoteric Oxides

Acid oxides are oxides of non metals that dissolve in water to form acids. 

Acid anhydrides are acids that are formed with water. 
Carbon dioxide dissolves in water to make a weak acid.
When sulfur dioxide is released into the atmosphere it dissolves in atmospheric water to form the sulfurous Acid, which oxidizes into a strong acid called sulfuric Acid. 

Nitrogen dioxide is another acidic oxide. 
Acid oxides react with alkaline solutions to form salts and water. 

The acidic oxide dissolves to form an acid which then reacts with alkali. 


All acidic oxides react with bases to form salts and water. 

Basic Oxides

Basic oxides are oxides of metals and contain the oxide ions, O2-

They are formed by metals. 

The oxides of Group I and some from Group II dissolve in water to form alkalis. 
Metal oxides other than Group I and II are insoluble and do not react with water. These oxides are basic and react with acids to form salt and water. 
All basic oxides react with acids to form salts and water. 

Amphoteric Oxides

Some metal oxides act as acidic oxides, they react with bases to form salts. 

Those oxides are called amphoteric oxides. Zinc oxide, ZnO, Lead(II) oxide, PbO and aluminum oxide, Al2O3 are all amphoteric oxides.


Acid Base Indicators And pH Scale



The pH Scale

pH is the measure of the degree of acidity or alkalinity of a solution. 

It runs from 0 to 14. A neutral solution has a value of 7. 0 – 7 is acidic and 7-14 is alkalic. 

Soil and pH

Soil tends to become more acidic over the years due to natural decay or organic material like dead leaves. It lowers the pH of the soil. Lime neutralizes the acidic soil. They use it in the form of calcium hydroxide or slaked lime. 

Farmers shouldn’t spread lime and ammonium fertilizer together. 


Salts

A salt of a compound formed when the hydrogen of an acid is totally or partially replaced by a metal. 

A salt is a compound formed when an acid reacts with a base. 
Some ions undergo hydrolysis in water that make the salt solution acidic or alkalic. 
Solutions of aluminium salts are acidic. 

Solutions of carbonates are alkaline.





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