basic chemistry notes and chemistry topics
basic chemistry notes and chemistry topics cover chemistry chapter — ACIDS, BASES AND SALTS, METALLURGY, CARBON AND ITS COMPOUNDS.
ACIDS, BASES AND SALTS (basic chemistry notes)
An acid is any compound that can react with a base to form a salt, the hydrogen of the acid being replaced by positive metallic ion. According to modern theory, an acid is a compound which yields hydrogen ions (protons) to a base in a chemical reaction. In a water solution, an acid tastes sour, turns blue litmus red and produces free hydrogen ions.
|Citric Acid||Lemons or Oranges (Citrus Fruits)|
|Lactic Acid||Sour milk|
|Formic Acid||Red ants|
- Such compound which gives salt and water acid known as bases. Bitter in taste turns red litmus paper into blue, contains the replaceable hydroxyl group.
- Some important bases are sodium hydroxide, potassium hydroxide, sodium carbonate and ammonium hydroxide.
- All alkalies are bases but all bases are not alkalies because all bases are not soluble in water.
- Salts are ionic compounds containing a positive ion (cation) and a negative ion (anion).
- When an acid reacts with a base, a salt and water are formed. This reaction is called neutralization since the acid and base neutralize each other’s effect.
- The process of decomposition of an electrolyte by the passage of an electric current through its molten state or its aqueous solution is called electrolysis.
- A device through which electric current is passed known as electrodes.
METALLURGY (basic chemistry notes)
- Metals occur in nature, in the native (in a free state) as well as in the combined state.
- Naturally occurring materials containing metals are called minerals.
- A mineral from which a given metal is obtained economically is called an ore.
- The process of extraction of a metal in a pure state on a large scale from its ore by physical and chemical means is called metallurgy.
- The rocky and siliceous matter that associated with the ore is known as gangue.
- A substance that is added to ore to remove the gangue is known as flux.
- The process of removal of gangue from the ore is known as concentration.
- Calcination is the heating of the ore in the absence of air. This method is employed for obtaining the metal oxides from carbonates and hydroxides.
- Roasting is the heating of the ore in the presence of air. In roasting, part of the ore is oxidized to form an oxide. This oxide is then reduced to the metal.
- The industrial reduction process for obtaining metal from the treated ore is called smelting.
CARBON AND ITS COMPOUNDS (basic chemistry notes)
- Such substances which have the same chemical properties, but differ in physical properties known as allotropes and this property is called allotropy.
- Diamond is the purest form of carbon.
- It is non-conductor of heat and electricity.
- It is the hardest natural substance.
- It burns in air at 900oC and gives out Co2.
GRAPHITE (BLACK LEAD)
- It is a good conductor of heat and electricity.
- Graphite is used in making lead pencils.
- Graphite is also used as electrodes, lubricant, moderators, electrotyping and carbon arc.
AMORPHOUS FORMS OF CARBON
- Wood Charcoal – Obtained from wood
- Sugar Charcoal – Obtained from cane sugar
- Bone or Animal Charcoal – Obtained from animal bones
- Coke Charcoal – Obtained from coal
CARBON MONOXIDE (CO)
- Carbon monoxide is an active poison and is very dangerous as it is a colourless and odourless gas and cannot, therefore, be easily detected.
- The extremely poisonous nature of carbon monoxide is a result of its combining with the haemoglobin of the blood too from carboxyhaemoglobin, which is not decompressed by any of the processes in the body.
- Compounds of carbon and hydrogen are called hydrocarbon.
- A natural source of hydrocarbon is petroleum obtained from sedimentary rocks.
- Compounds having the same molecular formula but differ in properties due to different structural formula is known as isomers and this property is called isomerism.
Saturated hydrocarbons (Alkanes)
- Containing single covalent bonds only.
- Such compounds are, in general, called alkanes for instance, Methane, Ethane, Propane, Butane.
- Containing multiple bonds.
- Compounds with double bonds are called alkenes, e.g. ethylene, propylene etc and triple bond-containing compounds are called alkynes, e.g. acetylene, propylene etc.
- Benzene is an unsaturated cyclic hydrocarbon with the structure.
- Compounds derived from benzene are called aromatic compounds.
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