To understand how to convert between moles, mass, and particles in chemistry, it’s important to know two key ideas: Avogadro's number and molar mass.

Key Ideas

1. What is a Mole?

   • A mole is a special way to count things in chemistry.
   • One mole holds about 6.022 x 10²³ particles.
   • These particles can be atoms, molecules, or ions.
   • This big number is called Avogadro's number.

2. What is Molar Mass?

   • Molar mass tells us how much one mole of a substance weighs.
   • It’s measured in grams per mole.
   • Molar mass matches the weight of an atom or molecule.
   • For example, water (H₂O) has a molar mass of about 18 grams per mole.

How to Convert

1. From Moles to Mass:

   • To find the mass of a substance when you know the moles, use this formula:
   • Mass (g) = Moles × Molar Mass (g/mol)
   • For example, if you have 2 moles of water, it would weigh:
     • 2 mol × 18 g/mol = 36 g

2. From Mass to Moles:

   • To find how many moles are in a certain mass, use this formula:
   • Moles = Mass (g) ÷ Molar Mass (g/mol)
   • For example, for 36 grams of water:
     • Moles = 36 g ÷ 18 g/mol = 2 mol

3. From Moles to Particles:

   • To change moles to particles, use this formula:
   • Particles = Moles × 6.022 × 10²³ particles/mol
   • For example, for 2 moles of a substance:
     • 2 mol × 6.022 × 10²³ particles/mol ≈ 1.2044 × 10²⁴ particles

4. From Particles to Moles:

   • To find moles from a number of particles, use this formula:
   • Moles = Particles ÷ 6.022 × 10²³ particles/mol
   • So, if you have about 1.2044 × 10²⁴ particles:
     • Moles = 1.2044 × 10²⁴ ÷ 6.022 × 10²³ ≈ 2 mol

Summary

By learning these simple formulas and ideas, students can easily switch between moles, mass, and particles in chemistry problems. Understanding these connections helps build a strong base for more advanced studies in science.