Topics in ChemistryLe 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
Which of the following isn't an element of the periodic table.
According to the periodic table, elements in the same group have got the same number of shells.
The periodic table of elements is also called the Mendeleev's table.
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)
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
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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A mixture can be generally categorized into 2 types. These are:
The prefix homo means sameness. A mixture is considered to be homogeneous when it has a uniform composition and appearance all through. For instance, the mixture of salt and water (saline) is a homogeneous mixture because the salt dissolves completely in water.
Note: The liquid forms of homogenous mixtures whose particles are completely dissolved are referred to as solutions. The solid to be dissolved in a solution is referred to as the solute while the liquid is termed the solvent. In short, the solvent dissolves the solute to form solution which is always a homogenous mixture.
The diagram below shows the homogenous mixture of a sugar solution:
In chemistry, a colloid is a homogeneous mixture with intermediate sized particles. It lies in the borderline between a solution and a suspension.
Although the solution of a homogeneous mixture appears to be physically pure, they are still impure because they are mixtures. Mixtures are not pure substances but elements are.
Other examples of homogenous mixtures include:
A mixture is said to be heterogeneous if it's composed of different substances that do not dissolve. The substances that make up a heterogeneous mixture are often visible to the eye.
A suspension is a heterogeneous mixture comprising of large sized particles. The particles can be seen to settle down or sediment below the liquid. An instance of suspension is a mixture of water and sand. This suspension (mixture) can be separated via a technique termed sedimentation and decantation. The image below illustrates this:
Examples of heterogeneous mixtures include:
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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:
Gold and copper are the only two non-silvery colored metals.
Copper is the only metal that is naturally antibacterial. This is why you would see some children utilize 'copper' water bottles in schools
Water actually 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
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.
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.
Calculate the Relative Molecular Mass of Methane (CH4). (Carbon=12.001 and H=1.00794)
Molecular Mass of Methane = 16.033 amu
Calculate the Relative Molecular Mass of Water (H2O). (Oxygen=15.9994 and Hydrogen=1.00794)
Molecular Mass of Water = 18.015 Da
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.
An acid is a substance that produces Hydrogen ions (H+) when dissolved in water (or when in the form of an aqueous solution).
Svante Arrhenius definition of Acid
An acid is a substance that donates a proton in a chemical reaction.
Brønsted Thomas Martin Lowry definition of Acid
An acid is a substance that accept an electron pair in a chemical reaction.
Gilbert Newton Lewis definition of Acid
Finally, Acids can also be also defined as substances that gives out hydronium ion (H3O+) when dissolved in water.
In summary, all acids will always contain the positive H+ (cation) and an anionic group in their formula. For instance, the acid HCl (Hydrogen Chloride) contains H+ as cation and Cl- as its anion.