2. STOICHIOMETRY – DAY 1 STOICHIOMETRY – DAY 1 (Converting from one substance to a DIFFERENT substance) Moles → Moles & Grams → Grams 1

3. What is Stoichiometry??? Convert from one substance to a DIFFERENT substance!!! Definition Definition: to predict the amount of reactant and/or product that will be used or produced in a chemical reaction. When doing stoichiometry, the chemical equation MUST BE BALANCED!!! 2

4. 3 The 1-2-3 Method for Solving STOICHIMETRY Problems 1.What are you trying to do? Identify the GOAL!!! 2.Determine what is GIVEN. ALWAYS start with what is given!! 3.Use conversion factors (RATIOS) Use balanced chemical equation for mole ratios

5. 4 General Mole Problem Sample Determine how many moles are there in 5.17 liters of Fe(C 5 H 5 ) 2. Goal = moles Fe(C 5 H 5 ) 2 Given 5.17 L Fe(C 5 H 5 ) 2 1 mole = 22.4 L 0.2 units match 1 mol Fe(C 5 H 5 ) 2 22.4 L Fe(C 5 H 5 ) 2 For STOICHIOMETRY, converting from one substance to a completely DIFFERENT substance! ADD MOLE RATIO STEP!!!

6. 5 Mole Ratios The coefficients in the balanced chemical equation provide the whole number mole ratios. ____ HCl + ____ Ba(OH) 2  ____ H 2 O + ____ BaCl 2 2 moles of HCl react with 1 mole of Ba(OH) 2 to form 2 moles of H 2 O and 1 mole of BaCl 2 Coefficients give MOLE RATIOS ExampleMole Ratio For 2 moles of HCl, 1 mole of Ba(OH) 2 is required to react

7. LEARNING CHECK Mole Ratios ____ N 2 + ____ H 2 → ____ NH 3 6 ExampleMole Ratio For each 1 mole of N 2, _______ moles of H 2 are required to react. For _________ moles of H 2, 2 moles of NH 3 will be produced.

8. 7 When N 2 O 5 is heated, it decomposes: 2 N 2 O 5 (g)  4 NO 2 (g) + 1 O 2 (g) a. How many moles of NO 2 can be produced from 4.3 moles of N 2 O 5 ? = moles NO 2 4.3 mol N2O5N2O5 8.6 b. How many moles of O 2 can be produced from 4.3 moles of N 2 O 5 ? = mole O 2 4.3 mol N2O5N2O5 2.2 2 N 2 O 5 (g)  4 NO 2 (g) + 1 O 2 (g) 4.3 mol? mol 2 N 2 O 5 (g)  4 NO 2 (g) + 1 O 2 (g) 4.3 mol ? mol Moles → Moles Conversions Units match Converting to a different substance, USE MOLE RATIO!!!

9. LEARNING CHECK Mole → Mole 2 PbO 2 → 2 PbO + 1 O 2 Using the balanced equation above, how many moles of PbO 2 where used if 2.3 moles of PbO was produced. 8 Converting to a different substance, USE MOLE RATIO!!!

10. 9 Converting Grams → Moles Goooooal!!!!! = moles C 2 H 4 Given 5.17 g CO 2 Use the MOLAR MASS to convert grams to moles. 0.1 MOLE RATIO Use the MOLE RATIO to convert from CO 2 to C 2 H 4 44 g CO 2 1 mole CO 2 2 mole CO 2 1 C 2 H 4 + 3 O 2  2 CO 2 + 2 H 2 O Determine how many moles of C 2 H 4 are required to produce 5.17 grams CO 2. 1 mole C 2 H 4

11. LEARNING CHECK Grams → Moles 10 Converting to a different substance, USE MOLE RATIO!!!

12. How many grams of AlCl 3 can be produced when 3.45 grams of Al are reacted with an excess of hydrochloric acid? 2 Al(s) + 6 HCl(aq)  2 AlCl 3 (aq) + 3 H 2 (g) Write the given amount of grams ABOVE the substances. 3.45 g? grams Gram → Gram Conversions

13. How many grams of AlCl 3 can be produced when 3.45 grams of Al are reacted with an excess of hydrochloric acid? 3.45 g ? grams Let’s work the problem. = g AlCl 3 3.45 g Al We must always convert to moles.Now use the molar ratio.Now use the molar mass to convert to grams. 17.0 Units Match

14. 2 N 2 O 5 (g)  4 NO 2 (g) + 1 O 2 (g) How many grams of N 2 O 5 are needed to produce 75.0 grams of O 2 ? = grams N 2 O 5 75.0 g O2O2 506 Converting Grams → Grams 75.0 g? grams

15. LEARNING CHECK Gram → Gram 2 KClO 3 → 2 KCl + 3 O 2 How many grams of KCl are produced if 15 grams of KClO 3 is used? Converting to a different substance, USE MOLE RATIO!!!