These MP Board Class 11th Chemistry Notes for Chapter 1 Some Basic Concepts of Chemistry help students to get a brief overview of all the concepts.
MP Board Class 11th Chemistry Notes Chapter 1 Some Basic Concepts of Chemistry
→ Laws of chemical combinations :
- Law of conservation of matter : In a chemical change, total mass of reactants and total mass of products are the same.
- Law of constant proportion : Ratio by weight of constituent elements in a chemical compound remains always the same.
- Law of multiple proportion : When an element of definite weight combines with an other element of definite weight, two or more than two compounds are formed in a simple ratio.
- Law of equivalence proportion : When two elements combine with a definite mass of an other element separately, the weight of both elements will be in the ratio in which they combine with each other or is simple multiple of that.
- Gay Lussac’s law : When gases react, their volumes are in simple ratio and volume of products ifgaseous are also in simple ratio of reacting gases.
→ Atomic mass : Atomic mass of an element is the number which shows that one atom of element is how many times heavier than that of 1/12th part of C12.
→ Molecular mass: Molecular mass of an element is the number which shows that one molecule of a compound is how many times heavier than 1/12 th part of C12 atom.
Molecular mass = 2 × Vapour density.
→ Mole : It shows collection of particles of a substance. In one mole of substance (molecule, atom or ion), number of particles are 6023 × 1023. It is also called as Avogadro’s number.
→ Volume of 1 mole of.a gas at N.T.R is 224 litre.
→ Percentage : Number of grams of solute present in 100 gm of a solution.
→ Molarity : No. of moles of solute in a litre of solution.
→ Percentage composition : Number of parts of each element present in 100 parts according to mass in a compound.
→ Chemical formula: Representation of molecule of a compound in terms of symbol of elements.
It is of three types :
- Empirical formula: Formula which gives simple whole number ratio of different elements.
- Molecular formula : Formula which gives exact number of different atoms present in a molecule.
- Structural formula : Represents the arrangement of various atoms present in molecule of compound.
→ Chemical Equation : The short representation of a chemical reaction in terms of symbols and formula of reactants and products.
→ Element: Substance made up of only one kind of atoms.
→ Compound : Compound is formed by the combination of two or more elements in a definite ratio.
→ Mixture : Mixture is formed by mixing two or more substances in any ratio.
→ There are seven basic units of measurement. All other units are derived from these.
→ Limiting reactants are those which are present in less amount in chemical reaction.
→ Total number of digits in a number are called significant figures.
→ Some useful conversion fractions :
1 pm = 10-12m, 1Å = 10-10m, 1 nm= 10-9 m
1L = 10-3 m3 = 1 dm3, 760 torr = 101325 Pa = Nm-2.
1 atm = 1.01325 bar
1 bar =105 Nm-2 = 105 Pa, 1 atm = 760mm Hg = 760 torr 1 calorie =4184 joule, 1 Electron volt = 1-6022 x 10-19 joule
Avogadro Number (N0) = 6 022 x 1023 (Atom, Molecule, ion or electron)
1 Atomic mass unit (amu or u) = \(\frac{\text { Atomic mass }}{\text { Avogadro Number }}=\frac{A}{N_{0}}\)
→ Normality (N) : Number of gram equivalent of solute per litre of solution.
→ Molality (m) : Number of moles of solute present in 1 kg solvent of the solution.
→ Mole Fraction : Ratio of number of moles of a component to the total number of moles of all the components of the solution.
In a mixture of solution number of moles of components 1 and 2 are n1and n2.
Mole fraction of component 1 will be
X1 = X1 + X2 = 1
Thus X1 = 1 – X2
→ Average mole mass of an element (\(\bar{M}\))
= \(\frac{\text { Sum of mole mass of Isotopes } \times \% \text { amount (abundance) }}{100}\)
Sum of mole mass of Isotopes X % amount (abundance)
or \(\bar{M}\) = Σfi × Ai
Where fi = Fraction of amount of Isotope
Ai = Sum of masses of Isotopes.