Chemistry: The Mole Concept and Conversions

What is the mass of one mole of oxygen?

Avogadro's number is 6 x 10^23 particles of a substance.

What does the symbol 'L' represent in chemistry?

One mole of aluminium weighs _____ grams.

Match the following elements with their relative atomic masses:

How many grams are in three moles of aluminium?

The relative molecular mass is obtained by adding the masses of all atoms in a molecule.

What is the formula to convert moles to grams for an element?

What is the relative molecular mass of water (H2O)?

One mole of water weighs 18 grams.

What is the relative molecular mass of sulfuric acid (H2SO4)?

The relative molecular mass of hydrated copper(II) sulfate, CuSO4.5H2O, is ______.

Match the following substances with their number of moles for given masses:

How many moles of water are in 117 g of water?

One mole of a substance always contains 6 x 10^23 particles.

How many moles are there in 0.25 moles of sodium?

The Mole Concept

Avogadro developed a method to count atoms and molecules.
If elements are weighed in the same proportions as their relative atomic masses, the same number of atoms will result.
The constant number of atoms in the elements listed is 6 x 10²³, called Avogadro's number (or constant), denoted by L.
One mole of a substance contains 6 x 10²³ particles of that substance.
The mass of one mole of an element is equal to its relative atomic mass in grams.
Example: One mole of sodium is 23 grams; one mole of oxygen is 16 grams.

Converting Moles to Grams

The mass of one mole of a compound is equal to its relative molecular mass in grams.
Example: The relative molecular mass of water (H₂O) is 18, so one mole of water is 18 grams.

Converting Grams to Moles

The number of moles of an element is calculated by dividing the mass of the element by its relative atomic mass.
Example: To find the number of moles in 36 grams of carbon, divide 36 by 12 (carbon's relative atomic mass), resulting in 3 moles.

Calculations Involving Avogadro's Number

One mole of a substance contains 6 x 10²³ particles.
To find the number of atoms or molecules in a given number of moles, multiply the number of moles by Avogadro's number.
Example: 0.25 moles of sodium contain 1.5 x 10²³ atoms.

Converting Numbers of Atoms or Molecules to Moles

To convert a number of atoms or molecules to moles, divide the given number by Avogadro's number (6 x 10²³).
Example: 9 x 10²² atoms of aluminum are equal to 0.15 moles.

Converting Numbers of Atoms or Molecules to Grams

To determine the mass of a given number of atoms or molecules, first calculate the number of moles, then multiply by the relative atomic or molecular mass.
Example: 3 x 10²³ atoms of zinc have a mass of 0.0325 grams.

This quiz covers essential concepts related to the mole, including Avogadro's number and how to convert between moles and grams. You'll explore definitions and calculations for both elements and compounds, providing a solid foundation in chemical measurement. Perfect for students looking to strengthen their understanding of chemistry principles.