CBSE Class 11 Chemistry Revision Notes Set 02

REMEDIAL ACTION PLAN

L‐1 Some Basic Concepts of Chemistry

Chemistry deals with the composition, structure and properties of matter.

Anything that has mass and occupies space is called matter.

Matter mainly exists in three forms ‐ solid, liquid and gaseous forms. These forms are inter convertible

by changing the temperature and pressure.

SOLID <‐‐‐‐> LIQUID <‐‐‐‐> GAS

Solids have a definite volume and definite shape. The particles are closely attached and there is not much freedom of movement.

Liquids does not have a definite shape but have a definite volume. The particles are not so close and there is a freedom of movement.

Gases neither have definite shape nor have a definite volume. The particles are situated as far as they can and are able to move freely.

BASIC CLASSIFICATION OF MATTER

Mixtures ‐ are the combination of two or more atoms which are combined in a ratio If the ratio is uniform throughout the mixture, then it is a homogeneous mixture If the ratio is not uniform throughout the mixture, then it is a heterogeneous mixture

Pure Substances ‐ consist of either one type of atoms or the combination of them in a fixed ratio. If only one type of atom is present in it, then it is called an element If more than one type is present, it is called a compound Molecules are are the combination of two or more atoms Physical Properties can be measured or identified without changing the composition of the substance. Chemical Properties occur due to a chemical change on the constituents.

Mass: It is the amount of matter present in a substance. It is independent of location. Weight: It is the amount of force excerted on an object by gravity. It changes according to the change in gravitational force.

Volume: It is the amount of space occupied by an object.

LAWS OF CHEMICAL COMBINATION

Law of Conservation of Mass (Antonie Lavoisier) ‐ Mass can neither be created nor be destroyed.

Law of Definite Proportions (Joseph Proust) ‐ A given compound always contains the same elements in the same proportion by mass.

Law of Multiple Proportions (John Dalton) ‐ When two or more elements combine to form more thanone compound, a fixed mass of one compound to a different mass of other always brings simple whole number ratios.

Gay Lussac's Law ‐ When gases combine or are produced in a chemical reaction, they do so in a simple ratio provided all gases are in the same temperature and pressure.

Avogadro's Law ‐ Equal Volumes of gases at the same temperature and pressure should contain equal number of molecules.

Scientific NotationIn which any number can be represented in the form N × 10n(Where n is an exponenthaving positive or negative values and N can vary between 1 to 10).e.g. We can write 232.508 as 2.32508 x102in scientific notation. Similarly, 0.00016can be written as 1.6 x 10–4

Precision refers to the closeness of various measurements for the same quantity.Accuracy is the agreement of a particular value to the true value of the result

Significant FiguresThe reliability of a measurement is indicated by the number of digits used torepresent it. To express it more accuratelywe express it with digits that are knownwith certainty. These are called as Significant figures. They contain all thecertaindigits plus one doubtful digit in a number. 

Convert the given amount to grams

Calculate the number of moles for each element

Divide the rest of the moles with the smallest one among them

Write the ratio with respect to elements

 

Molecular Formula ‐ It gives the exact number of various atoms in a given compound. It is calculated by:

Divide "Molar Mass" with "Empirical Formula"

Multiply the value with each element

Limiting Reagent ‐ It is the reactant which gets consumed and thus influence the amount of product formed.

Mass percentage‐

Mole Fraction of A = number of moles of A/(number of moles of A + number of moles of B)

Mole Fraction of B = number of moles of B/(number of moles of A + number of moles of B)

 

Molarity:

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