Chemical Calculations We now have 3 tools to complete chemical Calculations... Remember...Molar Mass and Avogadro's # are always compared to 1 mol of the substance 1. Molar Mass 2. Avogadro's # 3. Mole Ratio 1 mol X 6.02 x 1023 X Or (P.T.) g X 1 mol X Or # mol X # mol Y Or (P.T.) g X 1 mol X 1 mol X 6.02 x 1023 X # mol X # mol Y

Chemical Calulations 4 3 2 _ Fe + _ O2 _ Fe2O3 How many moles of Fe2O3 are produced when 6.0 moles O2 react? Follow the 3 Steps...1)what you know 2) what you want to know 3) how do you get there! 2 6.0 mol O2 mol Fe2O3 4.0 = mol Fe2O3 3 mol O2

Learning Check #2 2 3 4 _ Fe + _ O2 _ Fe2O3 How many moles of Fe are needed to react with 12.0 mol of O2 4 12.0 mol O2 mol Fe 16.0 = mol Fe 3 mol O2 A) 3.00 mol Fe B) 9.00 mol Fe C) 16.0 mol Fe

Converting moles of "X" into grams of "Y" Balance equation Use coefficients to write a mol-mol factor Mole Ratio # mol X # mol Y Convert moles of desired to grams Molar Mass (P.T.) g Y 1 mol Y

Learning Check #3 2 3 4 _ Fe + _ O2 _ Fe2O3 How many grams of O2 are needed to produce 0.400 mol of Fe2O3 (Remember…Get to Moles) mol O2 0.400 mol Fe2O3 3 = mol O2 .600 mol Fe2O3 2 mol O2 .600 g O2 31.98 g O2 = 19.2 1 mol O2

Converting grams of "X" into grams of "Y" Balance equation Convert grams of given (X) into moles of X Molar Mass (P.T.) g X 1 mol X Use coefficients to write a mol-mol factor Mole Ratio # mol X # mol Y Convert moles of desired to grams Molar Mass (P.T.) g Y 1 mol Y

Chemical Calculation The reaction between H2 and O2 produces 13.1 g of water. How many grams of O2 reacted? Write the equation _ H2(g) + _ O2(g) _ H2O(g) Balance the equation 2 1 2 _ H2(g) + _ O2(g) _ H2O(g)

Organize Your Data What you KNOW! What you WANT! How You get there! Mole Bridge g H2O mol H2O mol O2 g O2 Molar Mass Mole Ratio Molar Mass (P.T.) g H2O 1 mol H2O 2 mol H2O 1 mol O2 (P.T.) g O2 1 mol O2

Tool Box Once into moles … go where ever you want = = = The reaction between H2 and O2 produces 13.1 g of water. How many grams of O2 reacted? Once into moles … go where ever you want 13.1g H2O 1 mol H2O 18.01 g H2O = mol H2O .727 2 mol H2O 1 mol O2 .727 mol H2O = .364 mol O2 31.98 g O2 1 mol O2 .364 mol O2 = 11.63 g O2 Molar Mass Mole Ratio Molar Mass Tool Box (P.T.) g O2 1 mol O2 2 mol H2O 1 mol O2 (P.T.) g H2O 1 mol H2O

Set up your problem Convert Grams to moles! Cancel the units With More Practice Set up your problem Convert Grams to moles! Cancel the units Do the math 13.1g H2O 1 mol H2O 18.01 g H2O 2 mol H2O 1 mol O2 31.98 g O2 1 mol O2 = 11.63 g O2 (P.T.) g H2O 1 mol H2O 2 mol H2O 1 mol O2 (P.T.) g O2 1 mol O2

Points to Remember 1. Read an equation in moles 2. Convert given amount to moles 3. Use mole factor to give desired moles 4. Convert moles to grams grams (given grams (desired) moles (given) moles (desired)

= Learning Check # 4 4 2 Balance the Equation: Complete the set up: How many O2 molecules will react with 505 grams of Na to form Na2O? __Na + O2 __Na2O 4 2 Balance the Equation: Complete the set up: 1 mol O2 4 mol Na 6.02 x 1023 molelcules O2 1 mol O2 505 g Na 1 mol Na 22.99 g Na = 3.30 x 1024 molelcules 16

= 2 5 4 2 Learning Check #5 __C2H2 + __O2 __CO2 + __H2O 22.2 Acetylene gas C2H2 burns in the oxyactylene torch for welding. How many grams of C2H2 are burned if the reaction produces 75.0 g of CO2? __C2H2 + __O2 __CO2 + __H2O 2 5 4 2 = 75.0 g CO2 1 mol CO2 2 mol C2H2 26.0 g C2H2 22.2 g C2H2 44.0 g CO2 4 mol CO2 1 mol C2H2

Pathways for Problems Using Equations Given (A) Find (B) grams (A) grams (B) Molar Mass (A) Molar Mass (B) moles (A) moles (B) Mole Ratio Coefficients Avogadro's # Avogadro's # particles (A) particles (B) 20