NEET Chemistry Some Basic Concepts in Chemistry
Some Basic Concepts in Chemistry PDF Notes, Important Questions and Synopsis
SYNOPSIS
Basic Concepts of Chemistry
Classification of Matter:
Properties of Matter:
Physical properties: Colour, odour, melting point, boiling point, density
Chemical properties: Acidity, basicity, combustibility
The International System of Units (SI):
|
Physical quantity |
Symbol for quantity |
Name of SI unit |
Symbol for SI unit |
|
Length |
l |
metre |
m |
|
Mass |
m |
kilogram |
kg |
|
Time |
t |
second |
s |
|
Electric current |
I |
ampere |
A |
|
Thermodynamic temperature |
T |
kelvin |
K |
|
Amount of substance |
n |
mole |
mol |
|
Luminous intensity |
Io |
candela |
Cd |
Mass and weight:
- Mass of a substance is the amount of matter present in it, while weight is the force exerted by gravity on an object.
Temperature:
- Thermometer with the Celsius scale is calibrated from 0 to 100.
- The Fahrenheit scale is represented between 32 and 212.
- Negative values of temperature are not possible on the Kelvin scale.
Significant figures:
- Significant figures are meaningful digits which are known with certainty.
Laws of Chemical Combination
- Law of conservation of mass: Matter can neither be created nor be destroyed.
- Law of definite proportions: given compound always contains the same proportion of elements by weight.
- Law of multiple proportions: If two elements can combine to form more than one compound, the masses of one element which
combine with a fixed mass of the other element are in the ratio of small whole numbers. - Gay-Lusaac’s law of gaseous volumes: When gases combine or are produced in a chemical reaction, they do so in a simple ratio by volume provided all gases are at the same temperature and pressure.
- Avogadro’s law: Equal volumes of gases at the same temperature and pressure should contain equal number of molecules.
Atomic mass
- One atomic mass is defined as mass exactly equal to 1/12th the mass of one carbon-12 atom.
Molecular mass
- Molecular mass is the sum of atomic masses of the element present in the molecule.
Formula mass
- The formula mass of a molecule is the sum of the atomic weights of the atoms in the empirical formula of a compound.
Mole
- One mole is the amount of substance which contains as many particles or entities as there are atoms in exactly 12 g of the C-12 isotope.
Molar mass
- The mass of one mole of a substance in grams.
Empirical formula and molecular formula
- An empirical formula represents the simplest whole number ratio of various atoms present in a compound.
- A molecular formula shows the exact number of different types of atoms present in a molecule of a compound.
Stoichiometry
- Stoichiometry deals with the relationship between reactants and products involved in a chemical reaction to determine desired quantitative data.
Limiting reagent
- A limiting reagent in a chemical reaction is a substance which is totally consumed when the reaction is completed.
Concentration terms
- Molarity (M): Number of moles of a solute present in per unit volume of solution.
- Molality (m): Number of moles of a solute present in one kilogram of a solvent.
- Normality (N): Number of gram equivalents of a solute present in per unit volume of solution.
- Mole fraction: Ratio of the number of moles of a particular component to the total number of moles of the solution.
- Mass per cent or weight per cent (w/w%): Gram of solute present in 100 gram of solution.
- Volume by volume per cent (v/v%): mL of solute present in 100 mL of solution.
- Weight by volume per cent (w/v%): Gram of solute present in 100 mL of solution.
Videos
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A) 28g of CO contains 12g of carbon and 16g oxygen
B)one mole of CO reacts completely with half mole of O2
C)N2 and CO have same molar mass
D) all of these
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