1.5.2 Empirical and Molecular Formulas

• What does the empirical formula of a compound represent?

  Simplest whole number ratio
• The molecular formula provides complete composition details of a molecule


  True
• What is the key difference between empirical and molecular formulas?

  Simplest ratio vs. actual count
• The molecular formula of glucose is C₆H₁₂O₆, while its empirical formula is CH₂O.


  True
• Steps to calculate the empirical formula from percent composition

  1️⃣ Convert percentages to grams

  2️⃣ Calculate the moles of each element

  3️⃣ Determine the simplest mole ratio

  4️⃣ Multiply mole ratios to get whole numbers

  5️⃣ Write the empirical formula
• A compound containing 12 g of carbon and 4 g of hydrogen has an empirical formula of CH₄.


  True
• What does the molecular formula of a compound represent?

  Actual number and type of atoms
• The molecular formula shows the actual number of atoms in a molecule.


  True
• The empirical formula shows the basic composition
• A compound contains 40% carbon, 6.7% hydrogen, and 53.3% oxygen. What is its empirical formula?

  CH₂O
• The mole ratio for carbon in the empirical formula CH₄ is 1.


  True
• The empirical formula is always the same as the molecular formula

  False
• The molecular formula tells you exactly how many atoms of each element are present in a molecule.
• What does the empirical formula of a compound represent?

  Simplest whole number ratio
• Match the feature with the correct type of formula:

  Simplest ratio ↔️ Empirical Formula

  Actual atom count ↔️ Molecular Formula
• A compound containing 40% carbon, 6.7% hydrogen, and 53.3% oxygen has an empirical formula of CH₂O.


  True
• What does the empirical formula show about a compound?

  Simplest whole number ratio
• The molecular formula shows the actual number of atoms, while the empirical formula shows the simplest ratio
• The empirical formula represents the simplest ratio
• The molecular formula provides the complete details about the number of atoms in a molecule.


  True
• The mole ratio for hydrogen in the empirical formula CH₂O is 2.


  True
• Steps to calculate the molecular formula using the empirical formula and molar mass

  1️⃣ Determine the molar mass of the empirical formula

  2️⃣ Divide the compound's molar mass by the empirical formula's molar mass

  3️⃣ Multiply the subscripts in the empirical formula by the scaling factor

  4️⃣ Write the molecular formula
• What does the molecular formula of a compound represent?

  Actual number of atoms
• Match the feature with the correct formula type:

  Representation ↔️ Actual atom count

  Example for glucose ↔️ C₆H₁₂O₆
• The empirical formula shows the exact number of atoms in a molecule.

  False
• To determine the simplest mole ratio, divide each mole value by the smallest
• The simplest mole ratio is found by dividing each mole value by the smallest mole value.
• Match the feature with the correct type of formula:

  Actual number of atoms ↔️ Molecular Formula

  Simplest ratio ↔️ Empirical Formula
• The empirical formula represents the simplest whole number ratio of atoms in a molecule
• What is the empirical formula for glucose?

  CH₂O
• To calculate moles from mass, you divide by the molar mass
• A compound contains 12 g of carbon and 4 g of hydrogen. What is its empirical formula?

  CH₄
• The scaling factor for converting CH₂O to C₆H₁₂O₆ is 6.

  True
• The empirical formula represents the simplest whole number ratio of atoms
• Match the feature with the correct formula type:

  Representation ↔️ Simplest ratio

  Example for glucose ↔️ CH₂O
• The molecular formula of a compound represents the actual number and type of atoms
• What is the first step in calculating the empirical formula from percent composition?

  Convert percentages to grams
• What is the first step in calculating the empirical formula from mass data?

  Convert mass to moles
• The empirical formula for glucose is CH₂O, which is less complex than its molecular formula C₆H₁₂O₆.


  True
• What is the key difference between the empirical and molecular formulas of a compound?

  Simplest ratio vs. actual count