Electrolysis of aqueous solutions

Introduction:
Electrolysis is a process of breaking down (or decomposes) a chemical compound into its elements by using an electric current. The electric current is passed through an electrolytic cell, which consists of electrodes and electrolyte. Oxidation or reduction reactions occur in these electrodes. Electrolyte is a substance which contains free ions that make the substance electrically conductive. Electrolyte can be aqueous solution of molten ionic compound or the aqueous solution of ionic compound, alkali, or an acid. Hence electrolysis can be of two types
i) electrolysis of molten ionic compound
ii) Electrolysis of aqueous solutions.
Consider the example of sodium chloride (NaCl). Molten sodium chloride is obtained when we heat it till it melts. Whereas if, sodium chloride is dissolved in water, gives the aqueous solutions of sodium chloride. Solution of water of a substance is called the aqueous solution. Since the aqueous solution contains more than one type of ions, electrolysis of aqueous solutions is entirely different from that of molten electrolyte.

Electrolysis of aqueous solutions:

i)   Electrolysis of aqueous sodium chloride :
In the electrolysis of aqueous solutions, not only sodium chloride will dissociate into Na⁺ and Cl^-, but some of the water molecules will also decompose to give hydrogen (H⁺⁾ and hydroxide ions (OH^-). The reaction of electrolysis of aqueous solutions (of NaCl) can be written as follows,
              NaCl ---> Na⁺ + Cl^-
               H₂O ---> H⁺ + OH^-
In an aqueous solution, there can be more than one positive and one negative ion. There is a selective discharge, which means when there is a movement of ions to cathode or anode, only one negative ion and one positive ion will be selected to be discharged.

Electrolysis of aqueous solutions:

ii)  Electrolysis of Aqueous Sulphuric Acid
It is one of the examples of electrolysis of aqueous solutions.
The aqueous sulphuric has three types of ions. They are hydrogen ions (H⁺), sulphate ions (SO₄^2-), and also hydroxide ions (OH^-) from the water. The equation can be written as follows,
H₂SO₄ + H₂O --> 2H⁺ + SO₄^2- + H⁺ + OH^-
Diagram showing electrolysis of water:

The apparatus used for the Electrolysis of Aqueous Sulphuric Acid
There is more than one type of ion moving to the electrode, there is preferential discharge (also called as selective discharge) takes place.
The chemical reactions occur at anode and cathode is given in the table below.

At cathode	At anode
Here, each hydrogen ion (H+) gains electron and becomes hydrogen atom. Two of the hydrogen atom will combine and produce hydrogen gas molecule. Equation: 2H+ + 2e ---> H2	Here there is a choice of sulphate ions (SO42-) or hydroxide ions (OH-) Oxygen is gives off at anode, because of hydroxide ion is easier to discharge. Equation: OH- + 4e ---> O2 + H2O

Note:
When the electrolysis of aqueous solutions of dilute acids or alkalis is done, the volume of hydrogen given off at the cathode is approximately twice that of the oxygen gas at the anode.

Aqueous hydrogen fluoride

Introduction:
Electrolysis is a process of breaking down (or decomposes) a chemical compound into its elements by using an electric current. The electric current is passed through an electrolytic cell, which consists of electrodes and electrolyte. Oxidation or reduction reactions occur in these electrodes. Electrolyte is a substance which contains free ions that make the substance electrically conductive. Electrolyte can be aqueous solution of molten ionic compound or the aqueous solution of ionic compound, alkali, or an acid. Hence electrolysis can be of two types
i) electrolysis of molten ionic compound
ii) Electrolysis of aqueous solutions.
Consider the example of sodium chloride (NaCl). Molten sodium chloride is obtained when we heat it till it melts. Whereas if, sodium chloride is dissolved in water, gives the aqueous solutions of sodium chloride. Solution of water of a substance is called the aqueous solution. Since the aqueous solution contains more than one type of ions, electrolysis of aqueous solutions is entirely different from that of molten electrolyte.

Electrolysis of aqueous solutions:

i)   Electrolysis of aqueous sodium chloride :
In the electrolysis of aqueous solutions, not only sodium chloride will dissociate into Na⁺ and Cl^-, but some of the water molecules will also decompose to give hydrogen (H⁺⁾ and hydroxide ions (OH^-). The reaction of electrolysis of aqueous solutions (of NaCl) can be written as follows,
              NaCl ---> Na⁺ + Cl^-
               H₂O ---> H⁺ + OH^-
In an aqueous solution, there can be more than one positive and one negative ion. There is a selective discharge, which means when there is a movement of ions to cathode or anode, only one negative ion and one positive ion will be selected to be discharged.

Electrolysis of aqueous solutions:

ii)  Electrolysis of Aqueous Sulphuric Acid
It is one of the examples of electrolysis of aqueous solutions.
The aqueous sulphuric has three types of ions. They are hydrogen ions (H⁺), sulphate ions (SO₄^2-), and also hydroxide ions (OH^-) from the water. The equation can be written as follows,
H₂SO₄ + H₂O --> 2H⁺ + SO₄^2- + H⁺ + OH^-
Diagram showing electrolysis of water:

The apparatus used for the Electrolysis of Aqueous Sulphuric Acid
There is more than one type of ion moving to the electrode, there is preferential discharge (also called as selective discharge) takes place.
The chemical reactions occur at anode and cathode is given in the table below.

At cathode	At anode
Here, each hydrogen ion (H+) gains electron and becomes hydrogen atom. Two of the hydrogen atom will combine and produce hydrogen gas molecule. Equation: 2H+ + 2e ---> H2	Here there is a choice of sulphate ions (SO42-) or hydroxide ions (OH-) Oxygen is gives off at anode, because of hydroxide ion is easier to discharge. Equation: OH- + 4e ---> O2 + H2O

Note:
When the electrolysis of aqueous solutions of dilute acids or alkalis is done, the volume of hydrogen given off at the cathode is approximately twice that of the oxygen gas at the anode.

Group 14 elements: the carbon family

Introduction:
The carbon family elements in the periodic table that belong to the Group 14 or the IV A family are carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb) and Ununquadium (Uuq). The carbon family is unique in having one metal, three metals and two metalloids.

Properties of individual elements of the carbon family may be represented by the table below

Name of the Element	Represented by symbol	Atomic number	Atomic weight	Type	Electronic configuration of the elements
Carbon	C	6	12.011	Non-metal	[He]2s22p2
Silicon	Si	14	28.0855	Metalloid	[Ne]3s23p2
Germanium	Ge	32	72.61	Metalloid	[Ar]3d104s24p2
Tin	Sn	50	118.710	Metal	[Kr]4d105s25p2
Lead	Pb	82	207.2	Metal	[Xe]4f145d106s26p2
Ununquadium	Uuq	114	289	Metal	[Rn]5f146d107s27p2

The electronic configuration in the valence shells of the carbon family elements is ns², np².  Sharing of electrons is seen in most of the elements of the carbon family. As the size of the atom is increased, the tendency of the elements to lose electrons decreases. Similarly, the tendency of losing electrons decreases with the increase in the atomic number among the elements of the carbon family. The oxidation states of the elements in the carbon family are usually +4 and +2 for heavier elements because of the inert pair effect.

Individual elements in the carbon family:

Carbon: The first element known to humans and is the fourth most abundantly found element. Carbon exists both in elemental form and as allotropes, the most common being diamond and graphite.
Silicon: Crystalline metalloid that forms the foundation for the age of semiconductors. The common compound SiO₂ is abundantly found in earth’s crust.
Germanium: Used in manufacturing of semi-conductor devices. Rarely present in earth’s crust.
Tin: When pure, the metal is silvery white and is very soft. Forms low-melting alloys called solders that connect electric circuits.
Lead: Readily combines with the oxygen in the air forming Pb₂O, which results in the dulling of the surface on exposure to air.

Conclusion on carbon family:

The elements in the carbon family include a non-metal, two metalloids and three metals, varying greatly in their physical and chemical properties. These elements occur as elemental forms and in the form of compounds in nature. The elements of Group 14 are relatively non-reactive and usually tend to form covalent compounds with exceptions of tin and lead that form ionic compounds.

Common chemical formulas

Introduction: 

In order to study or describe the elements and molecules in simpler forms, chemical formulas are extensively used. For example simplest formula for water is H₂0, where H represents hydrogen and O is oxygen and subscript ₂ indicates the two atoms of hydrogen element joined together to form a molecule.

Applications of chemical formulas

• It is used to explain the kinds of atoms and their numbers in compound (or an element).
• The atoms of every element are characterized by different letters.
• A subscript is used when more than one atom present in a specific element
• It states the chemical composition of a compound by means of chemical symbols

Common chemical formulas for everyday substances and some common acids

NaCl- Table salt, NH₃ (Ammonia) and CH₄ (methane) used for cleanser and a gaseous fuel, C₆H₁₂O₆ - table sugar or glucose, Air contains mixture of N₂, O₂, CO₂, and other traces gas, H₂O₂ (hydrogen per oxide)- used as a antiseptic and to bleach or lighten hair, Aspirin - C₉H₈O₄, Hydrochloric acid (HCl),Nitric acid (HNO₃),Hydrocyanic acid (HCN), Perchloric acid (HClO₄), Sulfuric acid (H₂SO₄),Carbonic acid (H₂CO₃)

Some important common chemical formulas are given below

Acetic acid - CH₃COOH, Acetone - CH₃COCH₃, Ammonium hydroxide - NH₄OH, Aspirin - C₉H₈O₄, Benzene - C₆H₁₂, Boric acid - H₃BO₃,Butane - C₄H₁₀, Caffeine - C₈H₁₀N₄O₂, Calcium carbonate - CaCO₃, Calcium chloride - CaCl₂, Calcium hydroxide - Ca(OH)2, Calcium oxide – CaO, Calcium sulfate - (CaSO₄), Glucose - C₆H₁₂O₆, Hydrochloric acid - HCl, Hydrofluoric acid - HF, Magnesium sulfate - MgSO₄, Manganese dioxide - MnO₂, Methane - CH₄, Naphthalene - C₁₀H₈, Oxalic acid - H₂C₂O₄ , Potassium nitrate - KNO₃, Potassium sodium tartrate - NaKC₄H₄O₆ , Potassium oxide - K₂O, Potassium sulfate - K₂SO₄, Sodium bicarbonate - NaHCO₃, Sodium chloride – NaCl, Sodium hydroxide - NaOH, Sodium sulfate - Na₂SO₄, Sodium phosphate - Na₃PO₄, Sodium tetraborate - Na₂B₄O₇, Sucrose - C₁₂H₂₂O₁₁, Sulfuric acid - H₂SO₄, Water - H₂0, Zinc chloride- ZnCl

Chemical compounds

Introduction:
We are going to see about the important chemical compounds.  A chemical compound is one of the pure chemical substance composed of molecules and formed combination of more than one different chemically bonded chemical elements.  Elements are more stable when the compounds are combined to form together.  Some important chemical compound names are organic compound, inorganic compound, biomolecules, organometallic compounds and so on.

Organic compound- Important chemical compound

Some important chemical compounds are
Acetaldehyde:  It is an organic chemical compound and also occurs in coffee.  The general formula is CH₃CHO.
Benzene:  Benzene is also an organic chemical compound and it is flammable liquid.  General formula is C₆H₆.
Butene:  Butylene or butene is an chemical compound.  It is colorless gas.  General formula is C₄H₈.
Ethene:  Ethylene or ethene is one of the chemical compound.  It is flammable gas and colourless.  The general formula of ethene is C₂H₄.
Formic acid:  Methanoic acid or formic acid is the carboxylic acid.  The general formula of formic acid is HCOOH.

Inorganic compound- Important chemical compound

Some important chemical compounds are
Aluminium chloride:  Aluminium chloride (AlCl₃) is the combination of aluminium and chlorine.
Ammonia:  Ammonia (NH₃)is the chemical compound.  It is colourless gas and pungent odour.
Calcium chloride:  It is one of the important chemical compound.  CaCl₂ is the combination of calcium and chlorine compounds.
Chromic acid:  Collection of compounds. It is a powerful oxidized agent.
Gallium phosphate:  GaPO₄ or (gallium orthophosphate) is a colourless crystal.
Hydrogen chloride:  HCl  combination of hydrogen and chlorine atom and soluble in water.
Magnesium oxide:  MgO is a moisture absorbent.  It used as raw material for making cement.
Nitrogen monoxide:  It is a chemical compound with chemical formula NO.
Biomolecules:

Some important chemical compounds are
Acetic acid:  The general formula is CH₃COOH.  It is pungent smell and sour taste.
Cellulose:  The general formula is C₆H₁₀O₅.  It is one of the organic compound.

Air chemical equation

Introduction :

Air is usually made up of a mixture of so many gases. Air comprises slightly over 20% of oxygen (O₂) and in relation to 78% nitrogen (N₂). Air also contains surplus quantities of Carbon Dioxide (about 0.03%) and even smaller quantities of other inert gases like Helium, Neon, Argon, etc. It has some low level Ozone O₃. Air usually exists as a mixture of all these gases it does exist in the compound form. It also contains small and varying quantity of water vapor. Which we are looking as clouds in the sky.The air chemical equation are give in Table 1

Air chemical equation:Chief constituent of gases

The chief constituent of air is nitrogen gas followed by oxygen

The first two gases nitrogen and oxygen make up 99.0% of the atmosphere by volume.

Nitrogen is moderately inert because of its strong triple bond holding the atoms jointly in the molecule. Whereas, the oxygen gas is synthesized by photosynthesis and removed by combustion and respiration.

Types of Air chemical equation:

The types of air chemical equation as follows

Reaction with Acetaldehyde: Oxygen gas is used in the preparation of acetaldehyde (ethanol) involves the following steps.

2CH₃CH₂OH + O₂ →2CH₃CHO + 2H₂O

Further oxidation of ethanoic acid with give rise to acetic acid which on further oxidation with carbon dioxide and water takes place on burning.

2CH₃CHO + O₂ → 2CH₃COOH

Reaction with Aluminum: Secondly oxygen reacts with aluminum metal

Aluminum metal undergoes a combination reaction with O₂ (g).

4Al + 3O₂ →2Al₂O₃

Reaction with Copper hydroxide: Copper (II) hydroxide degraded into copper (II) oxide and water when heated.

Cu (OH) ₂ → CuO + H₂O

Reaction with Heptanes: Heptanes, burns in air to give carbon dioxide

C₇H₁₆ + 11O₂ → 7CO₂ + 8H₂OH

Reaction with methyl ter butyl ether: The gasoline additive MTBE (methyl tert-butyl ether), C₅H₁₂O₂ (l), burns in air.

C₅H₁₂O₂ + 7O₂ →5CO₂ + 6H₂O

Physical properties of Air chemical equation:

• Oxygen exhibits its Compressibility that is isothermal properties with the chemical compounds.
• Oxygen shows high conductivity towards air, water, and other fluids.
• It has high density gradient against air, water and other fluids, various solids and other common liquids.
• It is relatively rough to handle because of its high tensile strength.

Check my best blog Types of chemical reactions.

Types of chemical reactions

Introduction :
Chemical reaction is defined as the changing one set chemical reactions into other set of chemical reactions. There is no need to give input to the chemical reactions. Chemical reactions involves the transfer of electrons and the formation of chemical bonds. Reactants are the substance which are involved in the chemical reactions. Nuclear reactions are also takes place in the chemical reactions. There are three types of chemical reactions are present.

Different Types of Chemical Reactions:

There are three types of chemical reactions are present. The three types are defined in the following,
Oxidation reaction and reduction reaction:
Oxidation and reduction reaction are defined as one substance gets oxidised and the other substance gets reduced. Simply it is defined as the loss or gain of electrons. Some of the examples involves in this type of chemical reaction are,
1. Iron and oxygen reaction:
In this example, the ion reacts with the oxygen and it produces oxide. In this the oxidised substance is iron. The chemical reaction is as follows,
4Fe + 3O₂ `->`  2Fe₂O₃
Where
            Fe = iron
            O₂ = oxygen
            2Fe₂O₃  = oxide
2. Ethanol and oxygen reaction:
In this example, the ethanol reacts with the oxygen, thus producing an acid called ethanol. In this the oxidised substance is ethanol.
CH₃ CH₂ OH + [ O ]    `->` CH₃COOH
Where,

CH₃ CH₂ OH = ethanol

[ O ] = other chemicals

CH₃COOH = ethanoic acid

Acid – Metal oxide Reaction:
The formation of salt and water by using the reaction of acid and the metal oxide is called as the acid – metal reaction. The example of chemical reaction is, The acid hydrochloric acid reacts with the metal oxide iron oxide,thus producing  iron chloride and solvent water
3HCl + Fe₂O₃ `->` FeCl₃ + 3H₂O

HCl = hydrochloric acid

Fe₂O₃ = iron oxide

FeCl₃ = iron chloride

H₂O = water

Three types of chemical reaction

Acid – Base Reactions:
The formation of salt and water by using the reaction of acid and base are called as the Acid-Base reactions. The examples for this chemical reaction are ,
The acid hydrochloric acid reacts with the base sodium hydroxide, thus producing a salt called sodium chloride and solvent water
HCl + NaOH NaCl + H₂O
Where,
HCl = hydrochloric acid
NaOH = sodium hydroxide
NaCl = sodium chloride
H₂O = water

Another example,
The acid sulphuric acid reacts with the base potassium hydroxide, thus producing a potassium sulphate and the solvent water
H₂SO₄ + 2KOH K₂SO₄ + 2H₂O
Where,
H₂SO₄ = sulphuric acid
KOH = potassium hydroxide
K₂SO₄ = potassium sulphate
H₂O = water