Question of the Day Rules You must work alone You may not use your textbook today You have 6 minutes to complete the QOD Good luck!!

Balance the Equations a)P 4 + O 2  P 4 O 10 b)Li + H 2 O  H 2 + LiOH c)Bi(NO 3 ) 3 + K 2 S  Bi 2 S 3 + KNO 3

What are we doing Today? Stoichiometry Ch. 4 (EST) QOD Endo/Exo Lab Dec. 2 Don’t forget your test, Dec. 3 Tutorial Chapter 4 (ST) after school Stoichiometry Practice Problems

Stoichiometry p.112 & 113

Stoichiometry Consider the chemical equation: 4NH 3 + 5O 2  6H 2 O + 4NO There are several numbers involved. What do they all mean? “stochio” = Greek for element “metry” = measurement Stoichiometry is about measuring the amounts of elements and compounds involved in a reaction.

Stoichiometry Recall that Chemical formulas represent numbers of atoms 4NH 3 + 5O 2  6H 2 O + 4NO NH 3 1 nitrogen and 3 hydrogen atoms O2O2 2 oxygen atoms H2OH2O 2 hydrogen atoms and 1 oxygen atom NO 1 nitrogen atom and 1 oxygen atom

Stoichiometry Chemical formulas have molar masses: 4NH 3 + 5O 2  6H 2 O + 4NO NH 3 17 g/mol O2O2 32 g/mol H2OH2O18 g/mol NO30 g/mol ***To find the molar mass of a chemical formula – add the atomic masses of the elements forming the compound. Use the periodic table to determine the atomic mass of individual elements.***

Stoichiometry Recall that Chemical formulas are balanced with coefficients 4NH 3 + 5O 2  6H 2 O + 4NO 4 X NH 3 = 4 nitrogen + 12 hydrogen 5 X O 2 = 10 oxygen 6 X H 2 O= 12 hydrogen + 6 oxygen 4 X NO= 4 nitrogen + 4 oxygen

Stoichiometry With Stoichiometry we find out that 4 : 5 : 6 : 4 do more than just multiply atoms. 4NH 3 + 5O 2  6H 2 O + 4NO 4 : 5 : 6 : 4 Are what we call a mole ratio.

Stoichiometry 4NH 3 + 5O 2  6H 2 O + 4NO 4 : 5 : 6 : 4 Can mean either: 4 molecules of NH 3 react with 5 molecules of O 2 to produce 6 molecules of H 2 O and 4 molecules of NO OR 4 moles of NH 3 react with 5 moles of O 2 to produce 6 moles of H 2 O and 4 moles of NO

Stoichiometry Question (1) 4NH 3 + 5O 2  6H 2 O + 4NO How many moles of H 2 O are produced if 2.00 moles of O 2 are used? 2.00 mol O mol H 2 O = Notice that a correctly balanced equation is essential to get the right answer 6 mol H 2 O 5 mol O 2

4 mol NO 6 mol H 2 O Stoichiometry Question (2) 4 NH O 2  6 H 2 O + 4 NO How many moles of NO are produced in the reaction if 15 mol of H 2 O are also produced? 15 mol H 2 O 10. mol NO =

18.02 g H 2 O 1 mol H 2 O 6 mol H 2 O 4 mol NH 3 Stoichiometry Question (3) 4 NH O 2  6 H 2 O + 4 NO How many grams of H 2 O are produced if 2.2 mol of NH 3 are combined with excess oxygen? 2.2 mol NH 3 59 g H 2 O =

5 mol O 2 6 mol H 2 O 32 g O 2 1 mol O 2 Stoichiometry Question (4) 4 NH O 2  6 H 2 O + 4 NO How many grams of O 2 are required to produce 0.3 mol of H 2 O? 0.3 mol H 2 O 8 g O 2 =

Stoichiometry Question (5) 4 NH O 2  6 H 2 O + 4 NO How many grams of NO is produced if 12 g of O 2 is combined with excess ammonia? 4 mol NO 5 mol O 2 x 12 g O g NO = g NO 1 mol NO x 1 mol O 2 32 g O 2 x

Have we learned it yet? Try these on your own - 4 NH O 2  6 H 2 O + 4 NO a) How many moles of H 2 O can be made using 1.6 mol NH 3 ? b) what mass of NH 3 is needed to make 0.75 mol NO? c) how many grams of NO can be made from 47 g of NH 3 ?

Answers 4 NH O 2  6 H 2 O + 4 NO a) b) c) 6 mol H 2 O 4 mol NH 3 x 1.6 mol NH mol H 2 O = 4 mol NH 3 4 mol NO x 0.75 mol NO 13 g NH 3 = g NH 3 1 mol NH 3 x 4 mol NO 4 mol NH 3 x 47 g NH 3 83 g NO = g NO 1 mol NO x 1 mol NH g NH 3 x

Class Work 1)In your textbook p.133 Questions: 7, 8, 9 In your textbook p.135 Questions: B, C, D 2) Complete the PreLab 31 (Endothermic & Exothermic for Tuesday) and read the lab 18