Alfred Ajibola
- 15th October, 2026 @ 06:30 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
Petrochemicals are chemical products derived from petroleum (crude oil) or natural gas as the primary raw material, typically through refining (fractional distillation), and further chemical processing (e.g. cracking, polymerization and reforming).
Petrochemicals form the backbone of the modern plastics, synthetic fiber, synthetic rubber, detergent, solvent, and fertilizer industries. These important uses of petroleum makes it far more economically valuable than simply as a fuel source.
Below are common petrochemicals and their derivatives:
Ethene (ethylene): It is made from cracking naphtha/gas oil; and used to manufacture polyethene (polythene), plastic, ethanol, antifreeze (ethylene glycol).
Propene (propylene): They are used to manufacture polypropene plastic and other chemicals.
Benzene, toluene, xylene (BTX): These are aromatic petrochemicals used to make dyes, detergents, synthetic fibers (e.g. polyester, nylon), and solvents.
Butadiene: It is used to manufacture synthetic rubber.
Methanol: It is used as a solvent, fuel additive, and raw material for other chemicals.
Please read the introduction to hydrocarbons, their sources, classification, test and uses here.
Biodegradable wastes are wastes that can be broken down naturally by microorganisms (bacteria, and fungi) into simpler, harmless substances over a relatively short time.
Examples of biodegradable wastes include food scraps/leftovers, paper, wood, vegetable and fruit peels, cotton and other natural fibers, animal waste and sewage.
Non-biodegradable wastes are wastes that cannot be easily broken down by natural biological processes, or that take an extremely long time (sometimes centuries) to decompose.
Examples of no biodegradable wastes include plastics, polythene bags, glass, metals (cans, scrap metal), rubber, certain synthetic fibers (e.g. nylon), electronic waste (e-waste), and batteries.
Non-biodegradable wastes accumulate in the environment, causing long-term pollution. They can cause clogging of drains and waterways, harm wildlife (e.g. animals ingesting plastics and nylons), and can persist in landfills for very long periods (causing land pollution).
Biodegradable wastes undergo decomposition over a relatively short period of time. However, if they are not properly managed, they can still cause problems such as releasing odor, disease-causing organisms, water pollution (from their decomposition); but regardless, they are generally less persistent and can often be composted or used to generate biogas.
Please read on waste management here.
Pollution is the introduction of harmful substances (called pollutants) into the environment, causing adverse effects on living organisms and ecosystems.
Pollutants are classified under the following headings:
1. Air Pollutants
They include the following:
Carbon monoxide (CO) from incomplete combustion (vehicle exhausts, industrial processes).
Sulfur dioxide (SO₂) and oxides of nitrogen (NOₓ) from burning fossil fuels (especially coal, containing sulfur impurities). They also cause acid rain and respiratory problems.
Carbon dioxide (CO₂) is a major greenhouse gas contributing to global warming, from combustion of fossil fuels.
Particulate matter/soot/smoke generated from incomplete combustion and industrial emissions; causes respiratory illness.
Chlorofluorocarbons (CFCs) from refrigerants and aerosols. They deplete the ozone layer.
Volatile organic compounds (VOCs) from solvents, paints and petrochemical processes contribute to smog formation.
Please read on the oxides of carbon here.
2. Water Pollutants
They include the following:
Industrial effluents containing heavy metals (like lead, mercury, cadmium), acids/alkalis and toxic organic chemicals which are discharged into rivers/water bodies.
Oil spills from petroleum extraction, oil transportation in tankers, and refining processes.
Detergents and nitrates/phosphates fertilizers which can cause eutrophication; that is, an excessive algal growth that depletes dissolved oxygen, killing aquatic life.
Sewage and organic waste which increases biological/chemical oxygen demand (BOD/COD) in water bodies.
Plastic waste which harms marine and freshwater life.
Please read on the physical and chemical properties of acids, preparation, test and uses here.
3. Land/Soil Pollutants
They include the following:
Solid industrial waste, plastics, and non-biodegradable materials dumped on land.
Pesticides and agrochemicals that accumulate in soil, and can enter the food chain in ecosystems.
Heavy metals from mining and industrial waste, contaminating soil and affecting crop growth.
Improperly disposed e-waste (that is, discarded electrical or electronic devices like phones, laptops, video game consoles, etc,) releasing toxic substances into soil.
Please read on carbon and its allotropes here.
Citizens/Individual should practice proper waste disposal by separating biodegradable from non-biodegradable waste, thus avoiding indiscriminate dumping/littering.
They should reduce, reuse, and recycle materials (especially plastics, glass, metals, paper) to minimize waste generation.
They should avoid open burning of waste, which releases toxic fumes. Waste should be burned in an incinerator.
They should conserve water and energy to reduce demand on resources and pollution from power generation.
Individuals should support and participate in community clean-up and tree-planting (afforestation) programs.
Citizens should report illegal dumping or pollution activities to relevant authorities.
They should choose eco-friendly products (e.g. biodegradable packaging) where possible.
Citizens should educate themselves about environmentally responsible practices.
You can read on salts in chemistry here.
Government should formulate and enforce environmental laws and regulations (e.g. emission standards, waste disposal regulations, environmental impact assessments) before establishing new industries.
They should establish and empower regulatory agencies to monitor industrial activities and pollution levels (e.g. environmental protection agencies).
Government should set and enforce penalties/sanctions for industries and individuals that pollute the environment illegally, violating environmental laws
They should promote public awareness and environmental education campaigns.
Government should encourage and incentivize cleaner production technologies and renewable energy adoption through subsidies or tax incentives.
Government should provide adequate waste management infrastructure, proper landfill sites, recycling facilities, and sewage treatment plants.
Government should set aside and protect conservation areas, forests, and wildlife reserves.
Government should participate in international environmental agreements/treaties, (e.g. on climate change, ozone layer protection) and ensure domestic compliance of these treaties.
Government should fund research into pollution control technologies and sustainable industrial practices.
You can read on relative acidity and alkalinity (pH scale) here.
The table below shows the merit and demerits of chemical industries:
| Merits (Advantages) | Demerits (Disadvantages) |
| Employment and economic growth | Environmental pollution (air, water, land) |
| Production of essential goods (medicine, fertilizer, plastics) | Health hazards to workers and residents |
| Technological advancement | Risk of industrial accidents/explosions |
| Support for other industries | Depletion of natural resources |
| Infrastructural development | Contribution to global warming/ozone depletion |
You can read on bases and alkalis, their preparation, test and uses here.
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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:
