1. Determining Chemical Formulas
7.4

2. Empirical Formula
Empirical Formula – the ________ for the elements combined in a compound, with _________ showing the smallest whole-number mole ratio of the ____________ atoms in the compound.

3. Calculation
Calculate the empirical formula of a substance that is 78.1% B and 21.9 % H.
Assume you have _____ grams total.
Use molar mass to convert to moles of each.
Divide by the smallest # of moles.
Round to the nearest whole number.

4. Calculations
In a new alkaline battery, one substance is composed of 63.0% manganese and 37.0% oxygen by mass. Determine the empirical formula of the compound in the battery.
To make sure your answer is correct, calculate the % composition of all elements from your answer and compare.

5. Calculation
Determine the empirical formula of a compound that is composed of 60.0% carbon, 13.4% hydrogen, and 26.6% oxygen.

6. Calculations
Find the empirical formula of a compound found to contain 26.56% potassium, 35.41% chromium, and the remainder oxygen.

7. Molecular Formulas Molecular formula – the actual formula
x(empirical. form) = molecular form
x is a _________ number
Need the _________ ________ and the _________________ mass to determine molecular formula

8. Calculation
Diborane has a mass of and an empirical formula of BH3. Determine the molecular formula of diborane.
The empirical formula of a compound is found to be P2O5. The molar mass of the compound is 284 g/mol. Determine the molecular formula of the compound.

9. Calculations
Determine the molecular formula of a compounds that has an empirical formula of CH and a molar mass of g/mol.
Determine the molecular formula of a substance that has an empirical formula of CH2O and a molar mass of g/mol.

10. Calculations
Determine the empirical formula of a substance that is % Iron and % Chlorine.
Determine the empirical formula of a substance that is % Re and % O.