Maharashtra State Board · Class 10 · Chemistry · Chapter 2

Introduction to Matter — Mole Concept and Chemical Calculations — Formula Sheet

Board Formulas

9 formulas

1.Mole from Mass★
$n = \frac{m}{M}$
$n$ : Number of moles (mol) · $m$ : Mass of substance (g) · $M$ : Molar mass (g/mol)
Number of moles = given mass ÷ molar mass. Cornerstone of every stoichiometry problem.
2.Number of Particles★
$N = n \times N_{A}$
$N_{A}$ : Avogadro's number = 6.022 × 10^23 per mol
Total particles = moles × Avogadro's number. Works for atoms, molecules, ions.
3.Avogadro's Number
$N_{A} = 6.022 \times 1 0^{23} mol^{- 1}$
Number of particles present in 1 mole of any substance.
4.Molar Volume at STP
$V_{m} = 22.4 L/mol at STP$
1 mole of any ideal gas occupies 22.4 L at STP (0 °C, 1 atm).
5.Mass Percentage★
$% w / w = \frac{m _{so l u t e}}{m _{so l u t i o n}} \times 100$
Solution mass = solute + solvent. Fraction of solute in total solution mass.
6.Volume Percentage
$% v / v = \frac{V _{so l u t e}}{V _{so l u t i o n}} \times 100$
Common for liquid-in-liquid solutions such as alcohol content.
7.Percentage Composition
$% element = \frac{n \times atomic mass}{M _{co m p o u n d}} \times 100$
n = number of atoms of that element in one molecule. All %s must sum to 100.
8.Empirical Formula Ratio
$ratio = \frac{% mass}{atomic mass}$
Divide each by smallest, then round or multiply to whole numbers.
9.Molecular Formula from Empirical
$Mol. = n \times Emp., n = \frac{M _{m o l}}{M _{e m p}}$
n must be a positive integer (usually 1, 2 or 3).