1. Chemistry – Apr 13, 2018 P3 Challenge –
Determine the Empirical Formula for a compound that contains 36.61% chromium, 12.69% carbon and 50.7% oxygen.
Today’s Objective –
Moles and Chemical formulas
Agenda
Moles and Chemical formulas
Problem Solving
Assignment:
Chemical Formula Worksheet

2. Chemical formulas and Conversion factors
Because the chemical formula indicates the number and ratio of atoms in a compound, conversion factors can be written to convert between moles of atoms and moles of compounds.
Ex: 1 mole CO2 contains 1 mole of C and 2 mole of O
Ex: How many moles of O are present in 3.25 mol of H3PO4?

3. Gram – mole calculations using the chemical formula
Grams of X
Moles of Y
Grams of Y
Moles of X
Not Here!!
Molar mass
Chemical formula

4. Gram – mole –number of items problems
Grams of X
Moles of Y
Grams of Y
Moles of X
Not Here!!
Molar mass
Chemical formula
Number of X
Number of Y
6.022x1023
Atomic scale
Macroscopic scale
Liters of X
22.4

5. Gram – mole problems using the chemical formula
Grams of CO2
Ex: Determine the number of moles in a 15.0 g sample of CO2.
Ex: What mass does 1.25 moles of CO2 have?
Molar mass
44.01 g/mol
Moles of CO2

6. Gram – mole problems using the chemical formula
Moles of CO2
Moles of C
or O
Ex: Determine the number of moles of C in 8.30 mole of CO2.
Ex: Determine the number of moles of O in mole of CO2.

7. Gram – mole problems using the chemical formula
Grams of CO2
Ex: Determine the number of moles of C in 15.0 g of CO2.
Ex: Determine the number of moles of O in 15.0 g of CO2
Molar mass
44.01 g/mol
Moles of CO2
Chemical formula
Moles of C
or O

8. Gram – mole problems using the chemical formula
Grams of CO2
Grams of C, O
Molar mass
44.01 g/mol
Molar mass
12.01 g/mol, g/mol
Chemical formula
Moles of CO2
Moles of C, O
Ex: Determine the number of grams of a)carbon and b)oxygen in g of CO2.

9. Gram – mole – number problems using a chemical formula
Grams of X
How many copper atoms are present in a gram sample of copper (I) oxide, Cu2O?
Molar mass
g/mol
Moles of X
Chemical formula
Moles of Y
Macroscopic scale
Atomic scale
Number of Y

10. Gram – mole –number of items problems
Grams of X
Moles of Y
Grams of Y
Moles of X
Not Here!!
Molar mass
Chemical formula
Number of X
Number of Y
6.022x1023
Atomic scale
Macroscopic scale
Liters of X
22.4

11. Exit Slip - Homework
Exit Slip: How many grams of silver are present in 23.5 g of silver nitrate?
What’s Due? (Pending assignments to complete.)
Chemical Formula worksheet
What’s Next? (How to prepare for the next day)
Read p , p , 241 p