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
Charles's law states that the volume of a given mass of a gas is directly proportional to its kelvin temperature, provided the pressure remains constant. This law was formulated by French Physicist, Jacques Charles in 1780.
Please read a detailed explanation on Charles's law here.
Various instances of Charles's law are seen around us. They include the following:
Children who had dented their table tennis (or ping-pong) balls will be familiar with Charles's law through an attempt of fixing it.
One way they go about this process is by placing the dented surface of the table tennis ball on warm water for some time. As the ball floats, the increased temperature within that surface on the table tennis ball causes an increase in the volume of gas present inside the ball. This is what Charles's law entails; and it causes the table tennis ball to expand in this instance, until its dented surface is restored to normalcy.
Please read on molar mass and its calculations here.
Charles's law is applicable whenever yeast is utilized for baking purposes. Recall that yeasts serve the purpose of making our bakery products swell and fluffy. It is able to do this because it releases carbon (IV) oxide (CO2) when heated at high temperature.
As the temperature increases, the volume occupied by the gas bubbles of carbon (IV) oxide also increases through its spreading around the baked product, making it swell in the process.
Please read interesting facts for students here.
The baking of bread is a typical example of this process, and it works in accordance with Charles's law.
The pop-up turkey timer is a type of thermometer whose mechanism of action is based on Charles's law. Within this timer is a gas that expands based on the available quantity of heat (temperature).
Recall that with Charles's law, when temperature increases, volume also increases.
Please read the concept of heat and temperature here.
Before the heating or roasting process, the thermometer (timer) is inserted inside the turkey. As it gets heated up, the turkey's temperature increases, bringing about an expansion (increase in volume) of the gas within the thermometer. A volume will eventually be reached, and it results into a pop sound by the thermometer. This pop-up by the thermometer indicates that the turkey had been cooked.
Have you ever wondered why a balloon could burst without been touched? Well, the simple answer is Charles's law which states that an increase in temperature results into an increased volume at constant pressure.
When a balloon is filled with air (or helium gas), then tied and exposed to a sunny condition (high temperature), the volume occupied by the gas within the balloon increases due to the high environmental temperature. This causes the balloon to expand and eventually burst due to the lightness of its material, its elastic nature, the increased volume of its gas and an increased temperature.
However, the volume of gas occupied within the balloon decreases on cold days (due to low temperature). As a result, helium balloons tend to shrink on cold days.
Please read examples of Boyle's law in real life here.
Jaques Charles himself utilized his law when he had a hydrogen balloon flight. In fact he was said to be a lover of hot air balloon.
At a basic level, hot air balloon comprises of a burner, an envelop that stores hot air and a gondola (or basket) that carry passengers. In order to fly, the hot air inside the envelop is first heated immediately after the fuel source had been ignited.
This increased temperature causes the air to expand, thus increasing its occupied volume, while also making it lighter (since it has less mass per unit volume), in contrast to the denser cooler air present outside the envelop (that is, the atmosphere). The hot air balloon goes higher up the sky through this process.
Please read the concept of gravity on the solar system here.
When filled with air, a pool float enables one to float on water. However, it is quite common for a pool float to become under-inflated when placed on a pool. This happens as a result of Charles's law.
The cause of an under-inflated pool foalt is a result of the pool's low temperature. As a result, the volume of air within it is reduced, resulting into its slightly shrinked size.
Please read on heat transfer by convection here.
If the pool float were to be placed on warm water, its occupied gas volume will increase, making it inflated again.
It is a common observation that an inflated basketball shrinks in size when left under a cold environment. This is true because a decrease in temperature results into a corresponding decrease in volume according to Charles's law. Therefore, the volume of air inside the basketball shrinks on cold day.
As you may have guessed, the volume of the basketball will be regained when placed in an environment with higher temperature since the volume occupied by the air within it increases.
Please read on the game of basketball here.
Aerosols refers to products like insecticides, perfumes, deodorants, spray paints and so on. They usually have two compartments within their container. These are the primary liquid product, for instance, the perfume, paint or an insecticide chemical, and a highly pressurized sealed gas which had become solution.
If an aerosol is exposed to a very high temperature, it may explode. This is true because when heated, the pressurized gas expands and increases in volume. Since the gas cannot escape from its locked nozzle, it eventually explodes. In fact, this is the reason behind the warning signs on its container, indicating that it should be stored in a cool environment, and kept away from the sunlight and high temperature.
Please read the summary of kinetic molecular theory of gases here.
With regards to the human body system, the air capacity of the human lungs decreases during cold conditions. Simply put, the volume of air received in the lungs is somewhat reduced due to its decreased environmental temperature. This implies less energy for daily activities, and may impact adversely on the performance of athletes, especially sprinters.
On the contrary, the air capacity of the lungs increases on a sunny day (higher temperature), allowing more air into it. This mechanism is explained through an internal bodily regulation called homeostasis.
Please read more on homeostasis here.
Other examples of Charles's law in real life are observed in the following instances:
Opening a soda drink from a can or bottle
Inflating and deflating tyres
Storage of gas
Car engines
Boiling of water in a covered pot
Kindly share this article via the links below:
Please click here to contact Alfred if you require any of the following services:
If you need a standard website at an affordable price.
Online training on the academic subjects: biology, chemistry and basic science.
If you require an advanced smart school management system (web application) for your school.
Click here to read on Len Academy Smart School Software.
Please click here to follow Len Academy on Google News.
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:
