Alfred Ajibola
- 20th January, 2025 @ 09:24 AM
Topics in Chemistry
Chemistry Scheme of Work, SS1 Third Term Chemical Industries: Petrochemicals, Biodegradable, Non-biodegradable Wastes and Pollutants Chemical Industries: Types, Advantages, Disadvantages and Factors affecting Chemical Industries Hydrocarbons: Fractional Distillation of Crude oil and Uses of its Fractions Hydrocarbons: Sources, Classification and Test for Saturated and Unsaturated Hydrocarbons Trioxocarbonates: Preparation, Physical and Chemical Properties, Tests and Uses of Trioxocarbonates Carbon and its Compounds: Oxides of Carbon, Carbon(IV) oxide Carbon and its Compounds: Oxides of Carbon Amorphous Allotropes of Carbon Carbon: Structure and Allotropes of Carbon Salts in Chemistry: Types, Properties, and Uses of Salts Salts in Chemistry, their Classifications, Solubility, Preparations and Colors pH Indicators, Types of Indicators and Importance of pH and pOH Relative Acidity and Alkalinity (pH Scale), and Calculations on pH Bases and Alkalis: Definitions, Classification, Physical and Chemical Properties Bases: Preparation of Bases and Alkalis, Test and Uses Physical and Chemical Properties of Acids, Preparation, Test and Uses of Acids. Acid: Definition, Basicity, and Types of Acid Families of elements in the periodic table Periodic table and Classification of ElementsAcademic Questions in Chemistry
With regards to redox reactions, which of the following statement is wrong?
A. Redox reaction are examples of chemical change
B. Reduction is the gain of electron
C. Substances that donates election during chemical reaction are termed reductants
D. Oxidizing agents are always reduced in chemical reactions
E. Oxidation occurs at the cathode in electrolysis
F. Hydrogen is a reducing agent
In chemistry, physical change is associated only with the rearrangement of molecules while the internal composition of the substance remains the same.
A. True
B. False
_____ electron(s) is a term that describes the number of electron(s) in the outermost shell of an atom.
A. Outer
B. Excess
C. Valence
D. Positive
E. Negative
F. Last
_____ is the negative electrode in electrolysis.
A. Anode
B. Anion
C. Cathode
D. Cation
E. Ion
F. Electrolyte
The above diagram shows the _____ type of bond.
A. Covalent
B. Polar covalent
C. Coordinate covalent
D. Metallic
E. Van dear walls
F. Ionic
Metals are referred to as _____ in their impure state.
A. Diluted
B. Consecrated
C. Coloured
D. Ores
E. Stained
F. Strained
Metals generally have the quality to shine, glow, sparkle, glitter, reflect light and be polished. This characteristic of metals is termed _____.
A. State
B. Ductility
C. Luster
D. Malleability
E. Hardness
F. Inflorescence
The _____ spectrometry experiment conducted on isotopic elements gave a confirmation for the existence of isotopes.
A. Mole
B. Volume
C. Weight
D. Number of moles
E. Mass
F. Amount of substance
Collision theory is a fundamental concept in chemical kinetics that explains how chemical reactions occur and why reaction rates differ for various reactions.
At its core, this theory posits that for a reaction to take place, reactant molecules must collide with sufficient energy and appropriate orientation. This article will delve into the intricacies of collision theory, and the role of activation energy in facilitating chemical reactions.
The collision theory states that reactant particles must collide for a chemical reaction to occur; and they must collide with a certain minimum amount of energy termed 'activation energy'.
You can read an introduction to the rate of chemical reaction here.
Not all collisions result in a chemical reaction. Collisions which result into a chemical reaction, are termed effective collisions. Therefore, since the reactant particles are often in constant (or continuous) motion, they consequently possess kinetic energy. If this energy becomes sufficient, collision becomes effective, and chemical reaction occurs. This is represented in the image below:
From the above illustration on collision theory, it can be inferred that the rate and success of chemical reactions are dependent on three main factors. These are:
Energy of the reacting particles and their frequency of collision.
Orientation of the particles.
Activation energy of the reaction.
You can read on dynamic equilibrium in chemistry here.
This refers to the number of times reactants collide in a given period. The more frequent the collisions, the higher the probability that reactants will react. This frequency of collision is dependent on the amount of energy possessed by the reactants.
Factors that may increase (or decrease) the energy of particles, thereby affecting collision frequency include concentration (or pressure for gases), temperature, and the physical state of the reactants. For instance, increasing the concentration or temperature of reactants in a solution will subsequently increase the energy of reacting particles; thus, enhancing the likelihood of collisions.
Please read more on the factors that affect rate of chemical reaction here.
Not all collisions lead to a reaction. In this light, it is also vital that the molecules collide with the correct orientation. Reactive atoms or groups within the molecules must come into contact with the appropriate orientation during the collision. This is shown in the image below:
As an instance, in a bimolecular reaction, if two molecules collide in an improper orientation, they may bounce off without reacting. This is shown in the lower half of the above diagram. Therefore, the geometry of molecules plays a crucial role in ensuring productive collisions.
The energy involved in a collision must exceed a certain threshold to overcome the barriers of reaction. This energy is referred to as the activation energy (Ea), which is an essential concept in understanding the kinetics of chemical reactions.
You can read key points in chemistry here.
Activation energy is the minimum amount of energy required for reactants to undergo a transformation into products during a chemical reaction. This concept, introduced by Svante Arrhenius in the early 20th century, underlines the significance of energy barriers in determining reaction rates.
Activation energy is defined as the minimum amount of energy required by reacting particles to initiate (or start) a chemical reaction.
Please read on ionic theory and electrolysis here.
You can think of activation energy as a barrier which the reactants must overcome before a chemical reaction can proceed. In this regard, every reaction has got its own energy barrier (or activation energy); and those with lower activation energy will normally react quickly and spontaneously than those with higher activation energy.
Recall that bonds are present within reactant particles; and must be broken before a chemical reaction can proceed. In this light, activation energy also refers to the minimum energy required for breaking existing bonds (and creating new bonds) in reactants during a chemical reaction.
You can read on Dalton's atomic theory and its modifications here.
Note: A chemical reaction occurs only when the energy of the colliding reactant particles is 'equal to' or more than the activation energy. This is shown below:
In the image above, notice that the reactants' energy had equalled (or perhaps, just surpassed) the energy barrier (activation energy or Ea) for the reaction to commence. Meanwhile, it is noteworthy to state that the application of higher temperature (∆H) lowered the activation in the first reaction. In contrast, the little change in temperature (∆H) in the second reaction was not enough to sufficiently lower its activation energy.
You can read on the concept of heat and temperature in physics here.
As stated earlier, the activation energy can be influenced by a variety of factors, including temperature, the presence of catalysts, and the nature of the reactants. Generally, as temperature increases, the average kinetic energy of the molecules rises, leading to a higher likelihood of attaining the activation energy required for successful collisions. For this reason, most reactions proceed faster at elevated temperatures.
From the above paragraph, it can be stated that factors that affect activation energy will consequently affect the rate of a chemical reaction.
Please read detailed explanations on the factors that affect the rate of a chemical reaction here.
In conclusion, collision theory and activation energy are pivotal in comprehending how chemical reactions occur and how their rates can be manipulated.
By facilitating an understanding of the conditions necessary for reactants to collide effectively and the energy required to initiate a reaction, chemists can optimize reaction conditions for desired outcomes. This foundational knowledge is indispensable in various applications; from drug design in pharmaceuticals to the development of new materials in manufacturing.
Understanding these concepts not only propels academic inquiry but also translates into practical advancements across scientific disciplines.
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Amazing facts in Chemistry
Plastic and Glass can decompose, but not in our lifetimes. It takes an average time of 450 years for plastics to decompose. As for the decomposition of glasses, it takes about 4,000 years
The only letters that failed to appear on the periodic table are letters:
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
Below are the physical properties of metals:
They exist in solid state.
The have high densities.
They are good conductors of heat and electricity.
The have the ability to be polished, to glow, sparkle and reflect light.
They can be bent, flattened and made into sheets called foils.
They can be drawn into wires.
Iron undergoes magnetism while most metals are poorly magnetized.
They typical have high melting point.
They generally have high boiling point.
With the exception of lithium, sodium and potassium, most metals are generally hard.
They have the ability to make sound when in contact with other objects or metals.
Please read details on the physical properties of metals here
John Dalton is an English chemist who brought clarity into the composition of matter and the basis for their chemical reactions.
Below are Dalton's Atomic Theory:
All matter consists of tiny indivisible particles called atoms.
Atoms of the same element are identical to each other in every aspect because they have the same shape and mass, while atoms of different elements are different in all respect.
Atoms are indestructible and can neither be created nor destroyed.
Atoms of different elements can combine with each other in simple whole number ratios to form compounds.
Atoms of the same element share similar physical and chemical properties. They can also combine in more than one ratio to form two or more compounds.
Meanwhile, understand that the above theories of John Dalton had been modified.
Please read on Dalton's atomic theory and its modifications here
The periodic table, also called periodic table of elements or Mendeleev's table, is a table that shows an organized arrangement of the 118 chemical elements according to their atomic number.
Out of the 118 elements; elements 1 - 94 are present in nature while elements 95 - 118 are synthesized artificially.
The manner at which elements are arranged on this table reveals some similarities in their electronic configurations and chemical properties.
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)
Step 1: Identify the given parameter from the question.
Fe = 69.94%, O = 30.06%.
Empirical formula = Fe?O?
Step 2: Convert the percentages to gram. (just attribute grams to the %).
Step 3: To get the mole ratio of each element, convert the gram to moles using the formula (mole = mass/molarmass). Please merorize this formula because we always work with moles in emperical formula.
Mole of Fe: 69.94/55.85 = 1.252mol
Mole of O: 30.06/16 = 1.879mol
Step 4: Divide both sides by the smallest mole ratio.
Iron has the smallest mole ratio in our case, therefore: 1.252/1.252 = 1, 1.879/1.252 = 1.5
We now have the formula = Fe1O1.5
Step 5: Multiply each of the moles by the smallest whole number that will convert each into a whole number. (In our case, the number '2' is the smallest whole number that will make '1.5' and '1' whole numbers when multiplied by it.
For iron (Fe), we will have 1 x 2 = 2
For oxygen (O), we will have 1.5 x 2 = 3
Step 6: Write the empirical formula.
The empirical formula= Fe2O3
Iron(III)tetraoxosulphate(VI)
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:
Alkanes
Alkenes
Alkynes
They are shown in the image below:
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:
