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.
→ Avogadro’s law:
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.