# AP Inter 1st Year Chemistry Notes Chapter 5 Stoichiometry

Students can go through AP Inter 1st Year Chemistry Notes 5th Lesson Stoichiometry will help students in revising the entire concepts quickly.

## AP Inter 1st Year Chemistry Notes 5th Lesson Stoichiometry

→ Law of conservation of mass :
Matter can neither be created nor destroyed during a chemical change.

→ Law of definite proportions :
A given chemical substance (compound) always contains the same elements combined in a fixed proportion by weight.

→ Law of multiple proportions :
If two elements chemically combine to give two or more compounds, then the weights of one element which combine with the fixed weight of the other element in those compounds bear a simple multiple ratio to one another.

→ Gay-Lussac’s law of combining volumes :
When gases under similar conditions of temperature and pressure chemically combine they bear a simple ratio in their volumes.

Equal volumes of different gases, under similar condi-tions of temperature and pressure, contain equal number of molecules.

→ Molecular mass (molecular weight):
It is the sum of the atomic weights or atomic masses of all atoms present in the molecule.

→ Molar volume:
One gram molecular weight of any gaseous substance at STP occupies 22.414 litres volume.

→ Mole concept:
One mole is defined as the amount of substance that contains as many particles as there are atoms in exactly 12 g of the C12 isotope.

→ Molar Mass:
Mass of one mole of any substance in grams is called its molar mass.
E.g.: Molar mass of H2SO4 = 98 g

→ Gram atom & Gram molecule :
One gram atomic weight of a substance is termed as gram atom.
One gram molecular weight of a substance is termed as one gram molecule.
E.g.: One gram atom of oxygen = 16 g of oxygen.
One gram molecule of oxygen = 32 g of oxygen.

→ Equivalent weight of an element:
“A number which denotes the number of parts by weight of the element required to combine with or displace 8 parts by weight of oxygen (or) 1.008 parts by weight of hydrogen (or) 35.46 parts by weight of chlorine”.

→ Empirical formula:
Empirical formula of a compound is the simplest formula showing the relative number of atoms of different elements present in one molecule of the compound.

→ Molecular formula:
It represents the actual number of atoms of different elements present in one molecule of the compound.

→ Stoichiometry:
“The quantitative relationship existing between the quantities of the reactants and the products in a chemical reaction is known as stoichiometry.

→ Redox reaction :
The reaction that involves loss of electrons is called an oxidation reaction and that involving gain of electrons is called a reduction reaction. The overall reaction is called as redox reaction.

→ Types of redox reactions :
Chemical combination reactions, Decomposition reactions, Displacement reactions, Dispropor¬tionation reactions and comproportionation reactions.

→ Disproportionation: Reactions which involves the same element in the given form to undergo both oxidation and reduction simultaneously.
E.G. : 3Cl2 + 6OHΘ → ClO3 + 5Cl + 3H2O

→ Comproportionation reactions :
Reverse of disproportionation is comproportionation. In these reactions, two species with the same element in two different oxidation states form a single product. .
E.g.: Ag2+ + Ag → Ag+

→ Oxidation Number of a given species in the arbitrary charge the species appears to bear the given state.

→ Redox reactions are balanced either by ion electron method or by oxidation number method.

→ In the redox titration reactions, the completion of the titration is detected by end point.

→ Redox reaction takes place in Daniell cell is
Zn + Cu2+ → Zn2+ + Cu

→ Salt bridge in Galvanic cells provides an electric contact between the two solutions.

→ Molarity: No. of moles of solute present in 1 lit. of solutions.

→ Normality : No. of gram equivalent weights of solute present in 1 lit. of solution.

→ The meaningful digits which are known with certainty are called significant figures.
The uncertainty in the experimental (or) calculated values is indicated by mentioning the number of significant figures.