Chemistry as level what does di substituted mean

These definitions are the preferred ones to be used in Organic Chemistry. Note that some terms (such as configuration) have more than one interpretation.

acid: an agent able to produce positively charged hydrogen ions (H+). [Since the hydrogen ion is a bare proton, it usually exists in a solvated form (such as H3O+).]

achiral: not chiral. A compound (or object) that is superimposible on its mirror image. For example CH4.

activation energy: the miminmum energy which reacting species must possess in order to be able to form an 'activated complex', or 'transition state', before proceeding to the products. [The activation energy (Ea) may be derived from the temperature dependence of the reaction rate using the Arrhenius equation.]

addition reactions: reactions in which an unsaturated system is saturated or part saturated by the addition of a molecule across the multiple bond.[E.g. the addition of bromine to ethene to form 1,2-dibromoethane]

alkaloid: organic substances occurring naturally, which are basic, forming salts with acids. The basic group is usually an amino function.

allyl group: a group containing 3 carbon atoms and a double bond [C1=C2-C3, where C3 is called the allyliuc position or allylic carbon atom].

allylic rearrangement: the migration of a double bond in a 3-carbon system from carbon atoms one and two to carbon atoms two and three,

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.