Mole Concept And Molar Masses chapter 1 can study by students of class 11. These definitiona and formulas of Class 11 Chemistry Chapter 1: Some Basic Concepts of Chemistry is developed and witten by our expert teachers. Chemistry formulas. Mole Concept And Molar Masses is prepapred and collected from varius resources to help the students.
MOLE CONCEPT AND MOLAR MASSES
One mole is the amount of a substance that contains as many particles or entities as there are atoms in exactly 12 g (or 0.012 kg) of the 12C isotope.
The mass of one mole of a substance in grams is called its molar mass.
Empirical Formula for Molecular Formula
An empirical formula represents the simplest whole number ratio of various atoms present in a compound whereas the molecular formula shows the exact number of different types of atoms present in a molecule of a
compound.
Example
Molecular formula of glucose is C6H12O6 and there empirical formula will CH2O
STOICHIOMETRY AND STOICHIOMETRIC CALCULATIONS
Stoichiometry, deals with the calculation of masses (sometimes volumes also) of the reactants and the products involved in a chemical reaction. Before understanding how to calculate the amounts of reactants required or those produced in a chemical reaction,
Example
Let us consider the combustion of methane.
A balanced equation for this reaction is as given below :
CH4 (g) + 2O2 (g) → CO2 (g) + 2 H2O (g)
Thus, according to the above chemical reaction, we get
· Phase of reactant and product
· The coefficients 2 for O2 and H2O are called stoichiometric coefficients.
· One mole of CH4(g) reacts with two moles of O2(g) to give one mole of CO2(g) and two moles of H2O(g)
· One molecule of CH4(g) reacts with 2 molecules of O2(g) to give one molecule of CO2(g) and 2 molecules of H2O(g)
· 22.4 L of CH4(g) reacts with 44.8 L of O2 (g) to give 22.4 L of CO2 (g) and 44.8 L of H2O(g)
· 16 g of CH4 (g) reacts with 2×32 g of O2 (g) to give 44 g of CO2 (g) and 2×18 g of H2O (g).
Limiting Reagent
The reactant which is present in the lesser amount gets consumed after sometime and after that no further
reaction takes place whatever be the amount of the other reactant present is called limiting reagent. Or the reactant which gets consumed, limits the amount of product formed and is called the limiting reagent.
Mass per cent or weight per cent (w/w %) :
Mass % of an element = molar mass of that element x 100 / molar mass of compound
Mass % of a component = mass of component x 100 / total mass of the solution
Mole Fraction
It is the ratio of number of moles of a particular component to the total number of moles of the solution.
Mathematically
Mole fraction of component A = number of moles of component A / total number of moles
Molarity
Molarity is denoted by M. It is defined as the number of moles of the solute present in 1 litre of the solution.
Mathematically
Molarity (M) = No. of moles of solute / volume of solution in liter
Molality
Molality is denoted by m. It is defined as the number of moles of solute present in 1 kg of solvent.
Mathematically
Molality (m) = No. of mole of solute /Mass of solvent in Kg
