Topics in ChemistryLe Chatelier's Principle: Changes in Concentration and Pressure explained 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 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
Which of he following is not a fact concerning gold?
A. 24 karat gold is the purest gold element
B. It is the 50th rarest metal amongst all elements found beneath the earth crust
C. It is the most malleable and ductile pure metal ever known
D. It is the only metal with a golden color
E. Gold is non toxic and can be eaten with food
F. It's present inside the earth crust in all seven continents
Which of the following is not an example of a chemical change?
Which of the following is not a fraction of crude oil?
The Separating Funnel is a technique used in the separation of mixtures. Another name for Separating Funnel is the _____ Funnel.
2NH4+(aq) + Ag+(aq) -> 2H4AgN
The equation above represents _____ acid.
A. Svante Arrhenius'
C. Gilbert Lewis'
E. Sir Isaac Newton's
F. Albert Einstein's
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Recall that a mixture is made up of two or more substances physically combined.
In this article we will continue from where we previously stopped. In case you wish to read the Part one of this topic; it's present here.
Centrifugation involves the use of a device called centrifuge to separate the lighter portions of a mixture from the denser portions through the spinning action of the centrifuge.
Note: Blood is a mixture and its components can be separated via centrifugation.
Blood is considered a mixture because it is composed of liquid plasma and solid cells.
Below is an image of separated blood components via the process of centrifugation.
Using the above diagram as a reference, the test tubes containing the blood are inserted into the centrifuge.
The centrifuge begins to spin/rotate when it's switched on; and this is allowed to continue for about 5 to 10 minutes.
On bringing out the test tubes from the centrifuge, two different layers will be observed. These are:
Next, the plasma can then be carefully decanted from the test tube. (Please see sedimentation and decantation in the part 1 of this article).
Types of Centrifugation
Below are some of the types of centrifugation:
Matter exists in 4 states. These are:
On heating a solid, it changes to liquid. If we continue heating, the liquid will eventually change to gas. This is the usual sequence.
However, in sublimation, the heated solid does not pass through the liquid phase; instead, it changes to gas directly.
Sublimation can be defined as a process whereby a heated solid changes directly to gas without passing through the liquid phase.
A sublimate is a substance that changes directly from solid to gas or from gas to solid.
Such solids are said to sublime.
The diagram below shows sublimation via a solid that sublimes. (Ammonium Chloride or NH4Cl):
Examples of solids that sublime are:
Sublimation is used to separate two salts (or solids) in which one sublimes and the other does not.
An an instance, a mixture of common salt (NaCl) and iodine crystals (I) can be separated via sublimation.
On heating, NaCl remains in the heated dish or container while the iodine crystals sublimes; (that is; it changes into a gas and may be collected afterwards as the sublimate).
Distillation is a technique used to separate two or more miscible liquid that have different boiling points.
Note: The boiling points of the different liquids are not usually at a close range.
Think of miscible liquids as two or more liquids that can dissolve in each other (or one another).
The mixture of water and ethanol is a typical example of a mixture that can be separated via distillation. This is so because they are both miscible and have different boiling points.
The mixture of water and acetone are also miscible and can be separated via distillation.
The image below shows the separation of water and ethanol via distillation:
Steps involved in Distillation
Think of a distillate as a liquid collected from the process of distillation after it has been passed through a condenser.
When we have two liquids of different boiling points; the liquid with a lesser boiling point is said to be more volatile while that with a higher boiling point is said to be less volatile
Distillation can also be used to:
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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.