THE MOLE CONCEPT
Page 1
Page 2: Basic Cake Recipe
Flour: 2 cups
Sugar: 1 cup
Butter: 1/2 cup
Eggs: 3 large
Baking Powder: 1 teaspoon
Milk: 1 cup
Vanilla Extract: 1 teaspoon
Page 3: Understanding Molecular Mass and Mole Concept
Presenter: Mr. Ken Mitchell T. Morales
Page 4: Session Objectives
Lesson Objective 1: Define the mole and its significance in chemistry.
Lesson Objective 2: Understand Avogadro's number and its applications.
Lesson Objective 3: Apply the mole concept to solve problems related to molar mass and percent composition.
Page 5: Molecular Mass
Understanding the Mass Behind Chemical Reactions
Page 6: MOLECULAR MASS
The sum of all the masses of atoms present in the molecule of the substance.
Page 7: Steps in Solving Molecular Mass
Step 1: Determine the number of atoms of the elements present in the molecule.
Page 8: Steps to Determine the Number of Atoms
Identify the Molecular Formula:
The molecular formula shows types and numbers of atoms (e.g., H2O for water).
Analyze the Formula:
Look at the subscript numbers, which indicate atoms present. If no subscript, it means one atom.
Page 9: Count the Atoms
For each element in the molecular formula, write down the number of atoms based on the subscripts.
Example: For H2O:
Hydrogen (H): 2 atoms
Oxygen (O): 1 atom
Summarize the Counts:
Total number of atoms for each element (H – 2, O - 1).
Page 10: Review of Atom Counting Process
Reiterate counting atoms based on the molecular formula.
Example: H2O has 2 H atoms and 1 O atom.
Page 11: Summary of Counts
Final counts based on analysis of molecular formula:
Hydrogen (H): 2
Oxygen (O): 1
Page 12: Steps in Solving Molecular Mass
Step 2: Find the atomic mass of each atom using the periodic table, e.g.,
H – 1.00784 or 1.08 g/mol
O – 15.999 or 16.00 g/mol
Page 13: Multiplying Atomic Mass by Number of Atoms
Step 3: Multiply the atomic mass by the number of atoms present:
H: 2 x 1.008 g/mol = 2.016 g/mol
O: 1 x 16.00 g/mol = 16.00 g/mol
Page 14: Total Molecular Mass Calculation
Step 4: Get the sum of all products:
2.016 g/mol + 16.00 g/mol = 18.016 g/mol
Page 15: Example: Methane – CH4
Atom Counts and Masses:
Carbon (C):
Atoms: 1
Atomic Mass: 12.01 g/mol
Mass: 12.01 g/mol
Hydrogen (H):
Atoms: 4
Atomic Mass: 1.008 g/mol
Mass: 4.032 g/mol
Total Mass: 16.04 g/mol
Page 16: General Steps in Solving Molecular Mass
Identify elements in the molecular formula.
Count number of atoms for each element.
Multiply number of elements present by atomic number.
Sum all the products.
Page 17: Molecular Mass Calculation Worksheet
CHEM 103 Lecture
Duration: 25:00
Page 18: Understanding Formula Mass
The Significance of Mass in Chemical Formulas
Page 19: What is Formula Mass?
A general concept applicable to any chemical formula, including ionic compounds.
Based on empirical or molecular formula, represents mass of the entire formula unit (e.g., sodium chloride NaCl).
Page 20: Steps in Solving Formula Mass
Step 1: Write the Chemical Formula (e.g., NaCl).
Page 21: Identify Elements in the Formula
Step 2: List all elements in the formula.
For NaCl:
Sodium (Na)
Chlorine (Cl)
Page 22: Count Atoms in the Formula
Step 3: Determine how many atoms of each element:
Na: 1 atom
Cl: 1 atom
Page 23: Find Atomic Masses
Step 4: Look up atomic masses on the periodic table:
Na: 22.99 amu
Cl: 35.45 amu
Page 24: Multiply Atomic Mass by Number of Atoms
Step 5: Calculate total mass of each element:
Na = 1 x 22.99 amu = 22.99 amu
Cl = 1 x 35.45 amu = 35.45 amu
Page 25: Total Formula Mass Calculation
Step 6: Add the total masses to find the formula mass:
Total Formula Mass = 22.99 amu + 35.45 amu = 58.44 amu
Page 26: Example: Calcium Carbonate (CaCO3)
Atom Counts and Masses:
Calcium (Ca):
Atoms: 1
Atomic Mass: 40.08 amu
Mass: 40.08 amu
Carbon (C):
Atoms: 1
Atomic Mass: 12.01 amu
Mass: 12.01 amu
Oxygen (O):
Atoms: 3
Atomic Mass: 16.00 amu
Mass: 48.00 amu
Total Mass: 100.09 amu
Page 27: Formula Mass and Molecular Mass Comparison
Formula Mass vs. Molecular Mass:
Formula Mass: Uses amu, often for ionic compounds.
Molecular Mass: Uses g/mol, related to the mass of molecules.
Formula mass calculated through empirical formulas; molecular mass is through molecular formula.
Page 28: Formula Mass Calculation Worksheet
CHEM 103 Lecture
Duration: 25:00
Page 29: Think Tank Challenge
Activity to prompt discussion by providing questions and items related to each category.
Page 30: Think Tank Challenge Example 1
Items typically bought by the piece: List examples.
Page 31: Think Tank Challenge Example 2
Fruits sold by kilo or by the bunch: List examples.
Page 32: Think Tank Challenge Example 3
Items bought in pairs: List examples of shoes and socks.
Page 33: Think Tank Challenge Example 4
Foods often bought by the dozen: List examples besides eggs.
Page 34: Think Tank Challenge Example 5
Kitchen items typically bought by the set: Provide examples.
Page 35: Concept
Those counting units refer to tangible and visible materials.
Page 36: Question
How do we count invisible materials like atoms and molecules?
Page 37: The Mole
Connecting the Atomic World to the Macroscopic Scale
Page 38: Understanding the Mole
The mole is a unit relating to quantities, akin to dozen or pair.
Specifically measures number of atoms or molecules in matter.
Page 39: Connecting the Macroscopic to the Atomic
The mole links easily measured macroscopic properties (bulk mass) to fundamental properties (number of atoms/molecules).
Page 40: Avogadro's Number
One mole contains 6.02214076×10^23 discrete entities (atoms/molecules).
Known as Avogadro’s number or Avogadro constant (6.022×10^23/mol).
Page 41: Molar Masses of Compounds
The molar masses are necessary for calculating the number of moles of substances.
Page 42: Summation of Atomic Masses for Compounds
Molar masses = sum of atomic masses of all atoms present in the compounds.
Page 43: Unit of Measurement for Molar Mass
Commonly described in gram/mole (g/mol).
Page 44: Calculating Molar Masses
Molar mass computation is similar to molecular and formula mass calculations.
Page 45: Try This! Activity Introduction
Calculate molar masses of provided compounds:
Sulfuric acid (H2SO4)
Aluminum hydroxide (Al(OH)3)
Ammonium carbonate ((NH4)2CO3)
Page 46: Continue Try This! Activity
Further compounds provided for molar mass calculation:
Potassium sulfide
Oxygen fluoride
Sodium nitrate
Page 48: Credits
Presentation created by Slidesgo, with icons by Flaticon, images by Freepik.
Closing remark comparing mole concept to psychology in its ability to connect unseen and visible phenomena.