Alfred Ajibola
- Tue, 12th February, 2019 @ 11:12: AM
Topics in Chemistry
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 Mixtures and Separation of Mixtures Mixtures and Separation of Mixtures - part 2 Mixtures and Separation of Mixtures - part 3Academic Questions in Chemistry
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'
B. Brønsted–Lowry's
C. Gilbert Lewis'
D. Avogadro's
E. Sir Isaac Newton's
F. Albert Einstein's
According to Brønsted Thomas Martin Lowry, an acid is defined as _____.
A. Any substance that produces hydrogen ion (H+) when dissolved in water
B. A substance that accepts electron pair in a chemical reaction
C. A substance that gives out hydronium ion (H3O+) when dissolved in water
D. A substance that donates a proton in a chemical reaction
E. A substance that reacts with a base to form salt and water
F. A substance whose hydrogen ions (H+) are displaced after a reaction with metals higher in the activity, reactivity or electrochemical series
Which of the following is NOT a characteristic of chemical change?
Which of the following statement is FALSE concerning a physical change _____.
The following substances will sublime EXCEPT _____.
Which of the following is a state of matter?
The ideal way of separating a mixture of blood is through _____.
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The amount or quantity of a compound (or molecule) in chemistry can be measured in a variety of ways. The measured quantities will include:
Please read on Molar Mass, Worked Examples and it's Differences with Molecular Mass here.
In this article, we will explore the concepts of molecular mass.
Firstly, the term molecule refers to the composition and arrangement of atoms expressed in ratios.
Note: The atoms forming a molecule can be similar or different. For instance:
Recall that all elements have got their respective atomic masses; for instance Hydrogen (H) has an atomic mass of 1.00794 while that of carbon (C) is 12.011. The atomic mass of all the 108 elements can be seen on the periodic table.
Please read on the Periodic Table here.
The molecular mass of a substance or molecule is usually defined in relation to 12C (Carbon-12).
This is why it’s preferably called Relative Molecular Mass (RMM).
The Relative Molecular Mass value is obtained from the sum of the atomic masses of the constituent atoms or elements that make up the molecule.
Its unit is the Atomic Mass Unit (amu) or Dalton (Da).
Please read on Elements and their Characteristics here.
Note: To calculate the Relative Molecular Mass, we will have to take into consideration the atomic masses of each atom present in the molecule.
Calculate the Relative Molecular Mass of Methane (CH4). (Carbon=12.001 and H=1.00794)
Molecular Mass of Methane = 16.033 amu
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Calculate the Relative Molecular Mass of Water (H2O). (Oxygen=15.9994 and Hydrogen=1.00794)
Molecular Mass of Water = 18.015 Da
Calculate the Relative Molecular Mass of Ethanol (C2H5OH). (Carbon=12.001, Oxygen = 15.9994 and Hydrogen = 1.00794)
Molecular Mass of Ethanol = 45.036 amu
Please read on Graham's Law of Diffusion with some worked Examples here.
Note: We used 3 significant digits in all our answers.
This is so because the relative molecular mass is always defined and expressed in terms of 12C (Carbon-12) whose atomic mass has 3 significant digits.
The atomic mass of 12C is 12.011
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.
Note: Relative Molecular Mass prove to be useful only when we calculate substances with small and definite molecular sizes. This have been proven through the Modifications of Dalton's Atomic Theory.
Please read on Dalton's Atomic Theory and its Modifications here.
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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
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