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Pg:- 116,117,118,119 from textbook

1. Using Mass and Molar Mass

This method is one of the most commonly used and is straightforward when you know the mass of the substance and its molar mass.

• Mass of the substance (in grams): The mass of the sample you have, measured in grams.

• Molar mass (g/mol): The mass of one mole of a given substance, usually found on the periodic table for elements or calculated for compounds.

2. Using Volume (for Gases) and Molar Volume

For gases at standard temperature and pressure (STP: 0°C, 1 atm), the volume of one mole of an ideal gas is 22.4 liters.

• This formula is useful for gaseous substances when given volume data.

3. Using the Number of Particles and Avogadro's Number

If you know the number of particles (atoms, molecules, ions, etc.) of a substance, you can use Avogadro's number, which is 6.022×10^23 particles per mole.

• This is particularly useful in chemical reactions where the number of atoms or molecules is given.

4. Using Concentration and Volume (for Solutions)

For solutions, the concentration of the solute in moles per liter (molarity, M) and the volume of the solution in liters can be used to calculate moles.

• This method is especially used in titrations and preparing chemical solutions.

5. Using Density and Molar Mass (for Liquids and Solutions)

Sometimes, you know the density of a liquid and need to find the number of moles. This approach involves calculating the mass from the density and then using the molar mass to find moles.

• This method is particularly useful when dealing with pure liquids or concentrated solutions.