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
Chemistry plays a crucial role in numerous areas, including medicine, agriculture, manufacturing, and environmental science. However, it can also have adverse effects on our daily life activities.
Below are some potential negative consequences associated with chemical processes and substances:
Corrosion or rusting of iron occurs when iron is exposed to water and air (oxygen).
Corrosion can be regarded as the slow deterioration of iron to iron (III) oxide. This is shown via the chemical equation below:
Fe(s) -> Fe(aq) + 2e-
02(g) + 2H2O(l) + 4e- -> 40H(aq)
Fe(s) + 20H(aq) + 4e- -> Fe(OH)2(s)
Please read on the introduction to chemistry here.
Rusting can be prevented through the following methods:
Application of protective coating
Application of sacrificial metal
Cathodic protection
Alloying
Galvanising
Oiling and greasing
One of the main adverse effects of chemical industries is the pollution of our environment. Chemicals released into air, water, and soil can lead to pollution that adversely affect ecosystems and human health.
Pollution of our environment may result from:
Chemical wastes from factories and oil refineries
Radioactive wastes from nuclear plants
Oil spillage
Exhaust from motor vehicles
Also, it is noteworthy to state that pesticides, fertilisers and acid rain have made our environments unclean, while also posing threats to plant and animal life. In this regard, human health is also threatened by environmental pollution.
With regards to bioaccumulation, certain substances, like heavy metals or persistent organic pollutants, accumulate in organisms, entering food chains and may potentially harm wildlife and humans.
The process of eutrophication implies that excessive use of fertilizers can result in nutrient runoff, leading to algal blooms that degrade water quality and consequently harm aquatic life.
You can read on homogeneous and heterogenous mixtures here.
Drug abuse and drug addiction is a major problem in our society, especially among the youths. Drugs that are abused include heroin, cocaine and morphine. These drugs can becomed additive, and are thus sold by criminals in an attempt to make massive profit.
However, various countries have imposed strict laws to control pollution and drug abuse. Meanwhile, understand that the most effective control measure is via education.
Please read on the causes of drug abuse in adolescents.
Exposure to harmful chemicals (e.g., heavy metals, solvents, pesticides) can lead to toxicity and acute or chronic health issues, including respiratory problems, skin irritations, and cancers. Also, certain chemicals can provoke allergic reactions or sensitivities in some individuals.
Although medications, while beneficial, can also have adverse effects ranging from mild reactions to severe complications. Simply put, all drugs have got side effects.
With regards to food safety concerns, the use of synthetic additives, preservatives, and pesticides can lead to harmful residues in food products. Also, the improper use of chemicals in food production can result in contamination and foodborne diseases.
Please read on microorganisms causing food, water and air borne diseases.
This may result from chemical spills at workplace or exposure to harmful substances.
With regards to chemical spills, accidents in manufacturing or transportation can result in hazardous spills, threatening both human health and the environment.
Also, industrial workers may be exposed to harmful chemicals at their workplace, leading to occupational hazards and long-term health issues.
You can read on dynamic equilibrium in chemistry here.
Certain chemicals are used in warfare and can cause widespread harm, suffering, and death. A devastating example occured in world war II.
The atomic bomb dropped on Hiroshima on August 6, 1945, caused immense destruction, killing approximately 70,000 people instantly and more from injuries and radiation sickness by the end of the year. The blast, fire, and radiation created a "hellish" scene of widespread destruction. The bombing also caused long-term health issues for survivors, such as increased rates of cancer.
Please read on nuclear chemistry here.
Certain chemical processes, particularly in fossil fuel extraction and industrial production, contribute to greenhouse gas emissions, resulting into climate change.
The use of chemicals such as pesticides may bring about devastating effects on non-target species, leading to declines in biodiversity and disrupting ecosystems.
Also, the use of certain chemicals may enable the spread of invasive species that dominate organisms living in their natural habitat, causing ecological imbalance.
You can read on ecological succession here.
Contaminations that may have resulted from adverse effects of chemistry may require significant economic costs associated with its cleanup, for instance; oil spillage, eutrophication, and pollution.
Also, certain chemical industries may face heavy regulations due to the potential adverse effects of chemicals, impacting their operations and profitability.
Please read on the uses of chemistry here.
In conclusion, while chemistry has the potential to create solutions for various global challenges, careful consideration of its adverse effects is essential. In this light, responsible management, regulation, and ongoing research are crucial to mitigate these negative impacts while harnessing the benefits of chemical science.
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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:
