Mole Mastery Explainer
Mole Mastery
Chemistry Reference Guide
Stoichiometry • Topic 1.1
1. The Mole Concept
Atoms are too small to count individually. Scientists use the mole (mol) as a counting unit, similar to a "dozen."
1 Dozen = 12 items
1 Mole = \(6.022 \times 10^{23}\) items
Avogadro's Number
This number represents the particles in exactly one mole of a substance.
\(6.022 \times 10^{23}\)
2. Molar Mass (MM)
Molar mass is the mass (in grams) of one mole of a substance. Use the Average Atomic Mass from the periodic table.
Calculation Steps:
STEP 1
List all elements.
STEP 2
Find atomic masses.
STEP 3
Sum for total mass.
Example: \(H_2O\)
\(H: 2 \times 1.01 = 2.02\)
\(O: 1 \times 16.00 = 16.00\)
Total Molar Mass
18.02 g/mol
3. Conversion Roadmap
Divide
Mass \(\rightarrow\) Moles
"Starting with Grams"
\(\frac{\text{mass (g)}}{\text{MM (g/mol)}}\)
Multiply
Moles \(\rightarrow\) Mass
"Starting with Moles"
\(\text{mol} \times \text{MM}\)
Key Unit Equality
1 mole = Molar Mass (grams)
Stoichiometry Starter Practice Set
Stoichiometry Starter
Practice Set • The Mole & Molar Mass
Name:
Date:
Part 1: Counting Particles
1. Atoms in 2.5 moles of Gold (Au)?
2. Moles in \(1.204 \times 10^{24}\) molecules of \(H_2O\)?
Part 2: Molar Mass Calculations
| Formula | Work Area | Result |
|---|
| NaCl | | g/mol |
| Li2S | | g/mol |
| Ca(NO3)2 | | g/mol |
Part 3: Mass-Mole Conversions
-
Moles in 45.0g of NaCl? (MM = 58.44 g/mol)
-
Grams in 0.75 moles of Li2S? (MM = 45.94 g/mol)
-
Moles in 164.1g of Ca(NO3)2? (MM = 164.10 g/mol)
