1. Chem 105 Chpt 4 Lsn 8 1 CHAPTER 4 Chemical Equations and Stoichiometry Test 1 return Know elements 1-86 (symbol and spelling) Formulas must be balanced neutral (i.e. charge of 0) Given table 3.1 (pg 107) Test 1 return Know elements 1-86 (symbol and spelling) Formulas must be balanced neutral (i.e. charge of 0) Given table 3.1 (pg 107)

2. Chem 105 Chpt 4 Lsn 8 2 Balanced equations (from neutral formulas) Conservation of matter (Lavoisier) Conservation of matter (Lavoisier) Stoichiometry (stoichiometric coefficients) Stoichiometry (stoichiometric coefficients) Relationship between quantities prod. & react Relationship between quantities prod. & react 5 step process (pg 146) 5 step process (pg 146) Always start with neutral formulas Always start with neutral formulas

3. Chem 105 Chpt 4 Lsn 8 3 Conservation of matter (Lavoisier) p.169b

4. Chem 105 Chpt 4 Lsn 8 4 Balancing equations Aluminum and bromine combine to produce aluminum bromide. This is reacted with sulfuric acid (H 2 SO 4 ). Hydrogen bromide (HBr) and aluminum sulfate are produced. Aluminum and bromine combine to produce aluminum bromide. This is reacted with sulfuric acid (H 2 SO 4 ). Hydrogen bromide (HBr) and aluminum sulfate are produced. 1.) Write the formulas for the reactants and products. 2.) Balance the entire reaction. 3.) Verify an equal number of atoms on reactant and product side.

5. Chem 105 Chpt 4 Lsn 8 5

6. 6 Balancing an ionic equation Number of atoms and charge must be balanced. Number of atoms and charge must be balanced. Aluminum oxide (Al 2 O 3 ) and monatomic hydrogen gas combine to form water and aluminum ion. Aluminum oxide (Al 2 O 3 ) and monatomic hydrogen gas combine to form water and aluminum ion. Write formulas for balanced reactants and products. Write formulas for balanced reactants and products. Balance the reaction. Balance the reaction. Double check. Double check. Al 2 O 3 + 6 H +  2 Al 3+ + 3 H 2 O Al 2 O 3 + 6 H +  2 Al 3+ + 3 H 2 O

7. Chem 105 Chpt 4 Lsn 8 7 Balancing with a polyatomic ion Remember to keep the ion together Remember to keep the ion together Phosphoric acid (H 3 PO 4 ) and barium hydroxide combine to form barium phosphate and water. Phosphoric acid (H 3 PO 4 ) and barium hydroxide combine to form barium phosphate and water. Balance the starting material formulas and then the equation Balance the starting material formulas and then the equation H 3 PO 4 + Ba(OH) 2  Ba 3 (PO 4 ) 2 + H 2 O H 3 PO 4 + Ba(OH) 2  Ba 3 (PO 4 ) 2 + H 2 O 2H 3 PO 4 +3 Ba(OH) 2  Ba 3 (PO 4 ) 2 +6 H 2 O 2H 3 PO 4 +3 Ba(OH) 2  Ba 3 (PO 4 ) 2 +6 H 2 O

8. Chem 105 Chpt 4 Lsn 8 8 Mass relationships (use stoichiometric relation)

9. Chem 105 Chpt 4 Lsn 8 9 Mass relationships Fig. 4.8, p.159 Na 2 SO 4 (aq)+ BaCl 2 (aq)  NaCl (aq) + BaSO 4 (s)

10. Chem 105 Chpt 4 Lsn 8 10 Mass relationships Na 2 SO 4 (aq)+ BaCl 2 (aq)  NaCl (aq) + BaSO 4 (s) Balance the equation Balance the equation How many moles of NaCl will be produced from 0.81 moles of Na 2 SO 4 ? How many moles of NaCl will be produced from 0.81 moles of Na 2 SO 4 ? How many grams of NaCl will be produced from 0.81 moles of Na 2 SO 4 ? How many grams of NaCl will be produced from 0.81 moles of Na 2 SO 4 ? How many grams of BaSO 4 will be produced from 3.76 grams of BaCl 2 ? How many grams of BaSO 4 will be produced from 3.76 grams of BaCl 2 ? p.149

11. Chem 105 Chpt 4 Lsn 8 11 Limiting reactant (reagent) Which reactant is limiting? Which reactant is limiting? How much of product can be formed? How much of product can be formed? Ammonia gas can be prepared by the reaction of a metal oxide such as calcium oxide with ammonium chloride. If 112g of CaO and 224g of NH 4 Cl are mixed, what mass of NH 3 can be produced? Ammonia gas can be prepared by the reaction of a metal oxide such as calcium oxide with ammonium chloride. If 112g of CaO and 224g of NH 4 Cl are mixed, what mass of NH 3 can be produced?

12. Chem 105 Chpt 4 Lsn 8 12 Limiting reactant (reagent) 24. Aluminum chloride, AlCl 3, is made by treating scrap aluminum with chlorine. 24. Aluminum chloride, AlCl 3, is made by treating scrap aluminum with chlorine. 2 Al (s) + 3 Cl 2 (g)  2 AlCl 3 (s) If you begin with 2.70 g of Al & 4.05 g of Cl 2 a) Which reactant is limiting? b) What mass of AlCl 3 can be produced? c) What mass of the excess reactant remains after the hexane has been burned?

13. Chem 105 Chpt 4 Lsn 8 13 Next Lesson Percent yield Percent yield Chemical equations and chemical analysis Chemical equations and chemical analysis

14. Chem 105 Chpt 4 Lsn 8 14 p.162b

15. Chem 105 Chpt 4 Lsn 8 15 Balancing Equations ____C 3 H 8 (g) + _____ O 2 (g) ----> _____CO 2 (g) + _____ H 2 O(g) ____B 4 H 10 (g) + _____ O 2 (g) ----> ___ B 2 O 3 (g) + _____ H 2 O(g)