Chemistry

Ionic Theory and Electrolysis

len Alfred Ajibola - Sat, 28th December, 2019 @ 16:56: PM

Topics in Chemistry

Le Chatelier's Principle: Changes in concentration and pressure in dynamic equilibrium Chemical Equilibrium: Dynamic Equilibrium in Chemistry Static and Dynamic Equilibrium explained with their Differences Chemistry Scheme of Work, SS1, First Term Chemistry Scheme of Work, SS1, Second Term Chemistry Scheme of Work, SS1, Third Term Compounds in Chemistry: Characteristics of Compounds Types of Mixture: Homogenous and Heterogeneous Mixtures Mixtures: Characteristics of Mixtures Physical Properties of Matter explained with Examples Chemical Properties of Matter explained with Examples Differences between Physical and Chemical Change Ionic Theory and Electrolysis Physical and Chemical Properties of Acids States of Matter: Characteristics of Solids Liquid State of Matter: Characteristics of Liquids Gaseous State of Matter: Characteristics of Gases Molar Mass, Worked Examples and Differences with Molecular Mass Elements: Characteristics of Elements Salts and Types of Salt in Chemistry


Academic Questions in Chemistry

Please check out our Test Your Knowledge page to see all Questions and Answers

Which of the following isn't an element of the periodic table.

  • A. J

  • B. Y

  • C. W

  • D. B

  • E. U

  • F. K

According to the periodic table, elements in the same group have got the same number of shells.

  • A. True

  • B. False

The periodic table of elements is also called the Mendeleev's table.

  • A. True

  • B. False

The simplest formula of a compound is termed _____.

  • A. Emperical formula

  • B. Molecular formula

  • C. Avogadro's number

  • D. Mass formula

  • E. Molar mass formula

  • F. Mole ratio

A compound composed of iron (Fe) and oxygen (O) was analyzed and found to contain 69.94% iron and 30.06% oxygen. Find the empirical formula of the compound. (Molar mass of Fe=55.85, O=16)

  • A. FeO

  • B. Fe2O3

  • C. Fe3O4

  • D. FeO2

  • E. Fe3O6

  • F. Fe2O4

Which of the following statement is false concerning hydrocarbons?

  • A. Hydrocarbons can be aromatic

  • B. Hydrocarbons are made up of carbon and hydrogen only

  • C. Alkynes are aliphatic hydrocarbons

  • D. Alkenes have a carbon-carbon double bond in their structure

  • E. Benzene ring has a carbon-carbon triple bond in its structure

  • F. Hydrocarbons are the main constituents of petroleum and natural gas

The ability of carbon to form long chain of itself is called _____.

  • A. Carbon chain reaction

  • B. Catenation

  • C. Carbontion

  • D. Carbontion

  • E. Organic chemistry

  • F. Carbon moleculation

Calculate the relative molecular mass of methane. (Carbon = 12.001, H = 1.00794).

  • A. 13.00894 amu

  • B. 11.00206 amu

  • C. 12.00794 amu

  • D. 14.001 amu

  • E. 15.001 amu

  • F. 16.033 amu

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Ionic Theory:

The ionic theory is an important concept associated with electrolytes and electrolysis. This is so because electrolytes will always dissociate into ions during electrolysis.

By definition, an electrolyte is a solution or molten compound or paste-like compound that conducts electricity.

Note: Electrolytes are able to conduct electricity because they dissociates into two types of ions. These are cations and anions.

The equation below will be used to explain the ionic theory:

YZ -> A+ + B-

KCl -> K+ + Cl-

Ideally, the electrolyte (YZ or KCl) from the above instance should be in an aqueous form. In short, all electrolytes exists in aqueous (solution), or molten or paste-like forms. (Please see the definition of an electrolyte above).

So the above equation can be appropriately re-written as:

Y+Z-(aq) -> Y+(aq) + Z-(aq)

K+Cl-(aq) -> K+(aq) + Cl-(aq)

You can read on Salt and Types of Salts here.

Note: The process whereby molecules are splitted into ions in an electrolyte is known as ionization or dissociation.

All electrolytes do not ionize to the same degree. This is so because electrolytes fall into 2 categories. These are:

  1. Strong Electrolytes: They ionize or dissociates completely in solution. Examples are normal salts like sodium chloride and calcium chloride.
  2. Weak Electrolytes: They ionize or dissociates partially in solution. Ethanoic Acid (CH3COOH) is an example of a weak electrolyte.

From the above explanations, the ionic theory of electrolysis can therefore be related or linked to the ionization (or dissociation) of ions in solution.

The ionic theory of electrolysis states that substances whose solution conducts electricity will undergo electrolytic dissolution or dissociation or ionization.

Note: The ionic theory of electrolysis was first proposed by a Swedish scientist named Svante Arrhenius in 1887.

You can read on the Chemical and Physical Properties of Acids here.

 

What is Electrolysis?

Electrolysis is defined as the process of passing electricity into an electrolyte (through the electrodes), with the resultant decomposition of the electrolyte.

Note: The 'decomposition of the electrolyte' implies that the electrolyte is eventually broken down into its constituent elements.

Please read on Elements and their Characteristics here.

The elements deposited or liberated during electrolysis will vary in different ionic compounds. For instance, the elements deposited at the electrodes in the electrolysis of fused calcium chloride (CaCl2) will be different from that deposited in the electrolysis water (H2O).

Please read on Physical Change and Chemical Change here.

 

What are Electrodes?

Electrodes are defined as rods or plates that connect an electric circuit to the electrolyte; thus becoming the avenues through which electric current enters and leaves the electrolyte.

The diagram below shows the various components of electrolysis:
Electrolysis - Len Academy

Notice from the above diagram that the electrodes (cathode and anode) are in contact with the electrical circuit at one end and with the electrolyte at the other end.

Please read on the Physical Properties of Metals here.


Types of Electrodes

Electrodes are of two types. They are:

1. Anode: The anode is the positive electrode through which electric current (or electrons) leaves the electrolyte.

The anode will attract negatively charged ions (called anions) during electrolysis (or when current is passed through the electrolyte).


2. Cathode: This is the negative electrode through which electric current (electrons) enters the electrolyte.

The cathode will attract positively charged ions (cations) during electrolysis.


During electrolysis, oxidation occurs at the a anode while reduction occurs at the cathode.

Oxidation as the loss of electron(s).

Reduction is the gain of electron(s).

Note: An understanding of the terms (explained above) is crucial towards comprehending the electrolysis of different compounds.

The exact way and manner through which oxidation and reduction occur in electrolysis will be clearly explained in a subsequent article (on the electrolysis of various compounds).

At the moment, You can read on the definitions of Acid in regards to Oxidation and Reduction here.

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Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.


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Amazing facts in Chemistry

The only letters that failed to appear on the periodic table are letters:

J     &     Q

Gold and copper are the only two non-silvery colored metals.

Copper is the only metal that is naturally antibacterial. For this reason, some children utilize 'copper water bottles' in schools

Water freezes faster when it’s warm than when it’s cold

Most element in their pure state exists physically in different forms. For instance, pure carbon can exist as both diamond and graphite. This phenomenon is called allotropy

If you pour a handful of salt into a full glass of water, the water level will go down rather than overflowing the glass.

Similarly, if you mix half liter of water and half litre of alcohol, the total volume of the liquid will be les than one litre


NOTABLE POINTS IN Chemistry

In chemistry, hydrocarbons can be classified as either aliphatic or aromatic. Recently, both classifications of hydrocarbon were based on their structure rather than their origin.

Aliphatic hydrocarbons are put into three main groups according to the types of bonds they possess. These are:

  1. Alkanes

  2. Alkenes

  3. Alkynes

They are shown in the image below:

Alkanes, Alkenes and Alkynes - Len Academy

It's important to note the followings:

  • Alkanes have single bonds (only) in their structures.

  • Alkenes always have a carbon-carbon double bond present in their structure.

  • Alkynes always have a carbon-carbon triple bond present in their structure.

 

Aromatic hydrocarbons are classified into:

  • Arenes: They contain benzene ring as a structural unit. Below is the structure of a benzene ring.

Benzene Ring - Len Academy

 

  • Nonbenzenoid aromatic hydrocarbons: They possess special stability but lack a benzene ring as a structural unit.

Organic chemistry is the study of carbon and it's compounds.

Carbon is the focus of organic chemistry because it has a wide chemical diversity in the sense that it can combine with other carbon atoms to form a long chain of carbon molecule. This ability and process whereby carbon can form a long chain of itself is called catenation.

Please read the introduction to organic chemistry here

A major challenge encountered when calculating molecular mass is that it becomes difficult or impossible to calculate especially when the relative molecular mass of large molecules, polymers and macromolecules are involved.

Examples of large molecules (with indefinite molecular masses) include carbohydrates, cellulose and complex sugars.

The large molecules (above) have no specific chemical formula throughout their volume.

Please read more on carbohydrates and sugars here

Understand that Relative Molecular Mass prove to be useful only when we calculate substances with small and definite molecular sizes. This was proven through the modifications of Dalton's atomic theory.

Please read on Dalton's atomic theory and its modifications here.

Calculate the Relative Molecular Mass of methane (CH4). (Carbon=12.001 and H=1.00794)

  • Molecular Mass = Atomic mass of carbon + Atomic mass of Hydrogen

  • Methane is composed of one atom of Carbon and 4 atoms of Hydrogen.

  • 12.001 + (1.00794 x 4)

Molecular Mass of Methane = 16.033 amu

Please read more on molecular mass here


Calculate the Relative Molecular Mass of water (H2O). (Oxygen=15.9994 and Hydrogen=1.00794)

  • Molecular Mass = Atomic mass of Hydrogen + Atomic mass of Oxygen

  • Water contains 2 atoms of Hydrogen and 1 atom of oxygen.

  • (1.00794 x 2) + 15.9994

Molecular Mass of Water = 18.015 Da

Please read on emperical formula and its calculations here

Gold - Len Academy

Below are some facts about gold:

  • It is the only metal that has a gold (golden) color

  • Gold is present inside the earth crust in all the seven continents

  • Pure gold is soft and very stretchable (It can even be stretched into threads)

  • The Latin name of Gold is aurum which means 'shining dawn'. For this reason, its chemical symbol is 'Au'

  • Gold is a very good conductor of electricity. This is why it’s sometimes used in making USB and audio cables

  • Gold is non toxic and can be eaten with food. It is sometimes added to desserts in some expensive restaurants

  • The term Gold originated from an ancient English word 'geolu' which means yellow

  • 24karat gold is the purest gold element

Please read more interesting facts about gold here