AP 2/22 TEST TODAY  Please turn in the papers you were given by the sub on Friday (staple all together).  Have a seat next to someone you usually don’t sit by.  I AM NOT CHECKING LAB REPORTS TODAY, BE PREPARED TO TURN THEM IN TOMORROW  You will have all period to complete the test. Tomorrow we will start Thermochemistry and try to finish it up by next Friday. You will have a lab over Thermo possibly Tuesday.

2/22 Pre-AP  Today you will need the papers from the side table  WE will discuss test results and then you will work on a project that introduces stoichiometry using food.  Stoichiometry is the MOST important unit in pre-AP. Please make sure you don’t fall behind and get help is you are struggling.  Also, please check to make sure your name is on the airline project in the back. I am trying to get these graded and some have no name.

Warm-up~ mole-mole relationship notes  Answer A, B, and C from these notes. Show all work, box your answers, and use correct significant figures. You have 9 minutes to complete.

Stoichiometry Introduction to Stoichiometry Ideal Stoichiometric Calculations Limiting Reactants & Percent Yield

Introduction to Stoichiometry

Reaction Stoichiometry  Involves the mass relationships between reactants and products in a chemical reaction.  4 types of problems (given, unknown) Mole to mole Mole to mass Mass to mole Mass to mass

Conversion Factors  There are only 2 equalities that you will use to solve these problems!!  Always start with a balanced chemical equation.  From this, you can derive the mole ratio A conversion factor that relates the amounts in moles of any two substances involved in a chemical equation.

Mole Ratio 2Al 2 O 3(l)  4Al (s) + 3O 2(g)  We can write mole ratios that relate any two substances involved in the reaction.  For example:  Which substances you use and which in on top/bottom is determined by what you are converting to/from.

Answer the following as Practice:  1. oxygen and hydrogen react to produce dihydrogen monoxide. What is the mole ratio of oxygen to water? What is the mole ratio of hydrogen to oxygen?  2. hydrochloric acid reacts with sodium hydroxide to produce sodium chloride and water. What is the mole ratio of the acid to sodium chloride? What is the mole ratio of water to sodium hydroxide?

YOU TRY…  Answer the #2-4 from the “mole- mole relationship notes”

Molar Mass  The other conversion factor you may use is the molar mass.  Used to convert between moles and grams of the same substance.  Numbers are off of the periodic table and rounded off at the hundredths position before use.  Ex: Molar mass of Al 2 O 3 = 2(26.98 g/mol) + 3(16.00 g/mol)= g/mol

Ideal Stoichiometric Calculations

Pre-AP 2/23  Turn in the HW: mole to mole problems  Please pick up your poster from the side table and sit with your partner. You will be given 25 minutes of class time to finish the poster AND answer TWO questions from other classmates “recipe”  You will also need a calculator AND the “mass to mass” paper from the side table. We will continue learning how to calculate stoichiometry problems today. Thursday we will practice mass to mole and mole to mass. If you want to get ahead and practice, these notes are on my website. There is a quiz on Friday over ALL four types of calculations.

Quick Check: Calculate the following on a piece of paper. Make sure to include units and correct sig figs  1. The elements lithium and oxygen react explosively to form lithium oxide. How many moles of lithium oxide will form if 2 mole of lithium react with unlimited oxygen?  2. 2NaN 3(s)  2Na (s) + 3N 2(g) If mol of NaN 3 react, how many moles of N 2 would result?

4 types of problems  Mole to mole (Monday) Mole to mole  Mole to mass (Thursday) Mole to mass  Mass to mole (Thursday) Mass to mole  Mass to mass (Tuesday) Mass to mass  General pathway: Mass given  mole given  mole unknown  mass unknown

Mass to mass Mass given  mole given  mole unknown  mass unknown  Given quantity is a mass (g, kg, etc.)  Unknown quantity is a mass  Need 3 conversion factors to solve: Molar mass to convert from mass given to mole given Mole ratio to convert from mole given to mole unknown Molar mass to covert from mole unknown to mass unknown

Mass to mass example #1  What mass of aluminum is produced by the decomposition of 5.0 kg of Al 2 O 3 ?  Given: 5.0 kg Al 2 O 3  Unknown: ? g Al  Balanced eqn: 2Al 2 O 3  4Al + 3O 2  Answer: 2.6 kg

Mass to Mass example #2 4NH 3(g) + 5O 2(g)  4NO (g) + 6H 2 O (g) This reaction is run using 824 g NH 3 & excess O 2. How many grams of NO are formed? 2NaN 3(s)  2Na (s) + 3N 2(g) If mol of NaN 3 react, how many moles of N 2 would result ?

Mass to Mass example #3 2NaN 3(s)  2Na (s) + 3N 2(g) If mol of NaN 3 react, how many grams of N 2 would result ?

Mole to mole Mass given  mole given  mole unknown  mass unknown  Given quantity is in moles  Unknown quantity is in moles  Need 1 conversion factor to solve Mole ratio to convert between mole given & mole unknown

Mole to mole example  CO 2(g) + 2LiOH (s)  Li 2 CO 3(s) + H 2 O (l) How many moles of lithium hydroxide are required to react with 20. mol of CO 2 ?  Given: 20. mol CO 2  Unknown: ? mol LiOH

Mole to mole example  The elements lithium and oxygen react explosively to form lithium oxide. How many moles of lithium oxide will form if 2 mole of lithium react with unlimited oxygen?  Balanced eqn: 4Li + O 2  2Li 2 O  Answer: 1 mol Li 2 O

Mole to mass Mass given  mole given  mole unknown  mass unknown  Given quantity is in moles  Unknown quantity is mass (g, kg, etc.)  Need 2 conversion factors to solve: Mole ratio to convert from mole given to mole unknown Molar mass to convert from mole unknown to mass unknown

Mole to mass example  6CO 2(g) + 6H 2 O (l)  C 6 H 12 O 6(s) + 6O 2(g) What mass, in grams, of glucose is produced when 3.00 mol of water react with carbon dioxide?  Given: 3.00 mol water  Unknown: ? grams glucose

Mole to mass example  2NaN 3(s)  2Na (s) + 3N 2(g) If mol of NaN 3 react, what mass in grams of N 2 would result?  Given: mol NaN 3  Unknown: ? grams N 2  Answer: 21.0 g N 2

Mass to mole Mass given  mole given  mole unknown  mass unknown  Given quantity is a mass (g, kg, etc.)  Unknown quantity is in moles  Need 2 conversion factors to solve: Molar mass to convert from mass given to mole given Mole ratio to convert from mole given to mole unknown

Mass to mole example  4NH 3(g) + 5O 2(g)  4NO (g) + 6H 2 O (g) This reaction is run using 824 g NH 3 & excess O 2. How many moles of NO are formed?  Given: 824 g NH 3  Unknown: ? mol NO

Mass to mole example  4NH 3(g) + 5O 2(g)  4NO (g) + 6H 2 O (g) This reaction is run using 824 g NH 3 & excess O 2. How many moles of H 2 O are formed?  Given: 824 g NH 3  Unknown: ? mol H 2 O  Answer: 72.6 mol H 2 O

AP CHEM….  Take out a clean piece of paper  Answer the following WITHOUT looking at Kinetics notes 1. Define Kinetics. 2. What needs to happen to reactant molecules in order for successful collisions to occur to increase the rate of a reaction? 3. List and EXPLAIN three factors that affect the rate of a reaction. 4. How much of a temperature increase will double the reaction rate? 5. Describe how a catalyst such as manganese oxide speeds up a reaction.

AP  Pick up the graded papers from the side table  Leave your IMF test and Ch8/Ch9 Quiz out  Turn in the Practice AP Test

3/17 WELCOME BACK!  Pick up your graded papers or wait until someone passes them out.  On the back of the stoichiometry quiz, answer the following: 1. 4NH 3(g) + 5O 2(g)  4NO (g) + 6H 2 O (g) This reaction is run using 824 g NH 3 & excess O 2. How many grams of NO are formed? 2. 2NaN 3(s)  2Na (s) + 3N 2(g) If mol of NaN 3 react, how many moles of N 2 would result?

4NH 3(g) + 5O 2(g)  4NO (g) + 6H 2 O (g) This reaction is run using 824 g NH 3 & excess O 2. How many grams of NO are formed? 2NaN 3(s)  2Na (s) + 3N 2(g) If mol of NaN 3 react, how many moles of N 2 would result ?

Today you will need…  A calculator, a periodic table, the mass to mass worksheet you picked up Friday  Take out the mole ratio WS and TURN IN IF COMPLETED  If you didn’t finish, you have ten minutes  Answer the following on a piece of paper: The elements lithium and oxygen react explosively to form lithium oxide. How many moles of lithium oxide will form if 2 mole of lithium react with unlimited oxygen?

Mass to mass Mass given  mole given  mole unknown  mass unknown  Given quantity is a mass (g, kg, etc.)  Unknown quantity is a mass  Need 3 conversion factors to solve: Molar mass to convert from mass given to mole given Mole ratio to convert from mole given to mole unknown Molar mass to covert from mole unknown to mass unknown

Mass to mass example  NH 4 NO 3(s)  N 2 O (g) + 2H 2 O (l) How many grams of NH 4 NO 3 are required to produce 33.0 g N 2 O?  Given: 33.0 g N 2 O  Unknown: ? g NH 4 NO 3

AP  Take out Kinetics notes

Mass to mass example  What mass of aluminum is produced by the decomposition of 5.0 kg of Al 2 O 3 ?  Given: 5.0 kg Al 2 O 3  Unknown: ? g Al  Balanced eqn: 2Al 2 O 3  4Al + 3O 2  Answer: 2.6 kg

Today you will need…  The lab paper from the side table  Pick up YOUR graded papers  A calculator, a periodic table, something to write with  Take out the mass to mass homework  We will practice mole to mole and mass to mass problems today  We will also prepare for the lab you have Wednesday/Thursday

Add the following questions to your mass to mass HW from last night. These will count as 8, 9, 10 In a very violent reaction called a thermite reaction, aluminum metals reacts with iron(III) oxide to form iron metal and aluminum oxide according to the following equation: Fe 2 O 3 + Al  Fe + Al 2 O What is the mole ratio of Al to Fe? Of aluminum oxide to iron (III) oxide? 9. What mass of Fe will be produced from 130. g of Fe 2 O 3 ? 10. How many moles of Al will react with 2.58 moles of Fe 2 O 3 ?

Ideal conditions  These problems tell us the amount of reactants or products under ideal conditions. All reactants are completely converted into products. Give the maximum yield we could expect, but this is rarely attained in the field because we don’t have ideal conditions.

4 th /6 th  Need: Paper from table, calculator, something to write with On a clean piece of paper:  Explain limiting reactant  Explain excess reactant (this will be turned in)

Limiting Reactants & Percent Yield

Limiting & excess reactants  Once one of the reactants is completely used up in a rxn, it doesn’t matter how much of the other reactant(s) you have. The reaction cannot continue.  Limiting reactant: The reactant that limits the amounts of the other reactants that can combine and the amount of product that can form in a chemical reaction.

Limiting & excess reactants  Excess reactant(s) Substance(s) that are not completely used up an a rxn and do not limit the amount of product that can be formed. These are the reactants that are “left over” at the end of a rxn.

Which is limiting? Excess?  To decide which reactant is limiting in a rxn, use one of your givens to solve for the other.  Then compare how much you have (given) to how much you need under ideal conditions (solved for). If you have more than you need, the 1 st substance is limiting. If you have less than you need, the 2 nd substance is limiting.

Limiting reactant example  CO (g) + 2H 2(g)  CH 3 OH If 500. mol of CO and 750. mol of H 2 are present, which is the limiting reactant? Solve to determine how much H 2 would be needed to completely react 500. mol CO. Do you have 1000 mol H 2 ? No, you only have 750. mol. H 2 is the limiting reactant.

Limiting reactant example 3ZnCO 3(s) + 2C 6 H 8 O 7(aq)  Zn 3 (C 6 H 5 O 7 ) 2(aq) + 3H 2 O (l) + 3CO 2(g)  If there is 1 mol of ZnCO 3 & 1 mol of C 6 H 8 O 7, which is the limiting reactant?  Answer: 1 mol ZnCO 3 could react with 0.67 mol C 6 H 8 O 7, which is less than is available. ZnCO 3 is limiting.

Limiting reactant example  Aspirin, C 9 H 8 O 4, is synthesized by the rxn of salicylic acid, C 7 H 6 O 3, with acetic anhydride, C 4 H 6 O 3. 2C 7 H 6 O 3 + C 4 H 6 O 3  2C 9 H 8 O 4 + H 2 O When 20.0g of C 7 H 6 O 3 and 20.0g of C 4 H 6 O 3 react, which is the limiting reactant? How many moles of the excess reactant are used when the rxn is complete? What mass in grams of aspirin is formed?  C 7 H 6 O 3, mol, 26.1 g

Percent Yield  Theoretical yield-maximum amount of product that can be produces from a given amount of reactant. This is what we calculate using ideal stoichiometric calculations.  Actual yield-the measured amount of a product obtained from a rxn.

Percent Yield  Ratio of the actual yield to the theoretical yield, multiplied by 100.

Percent Yield example  C 6 H 6(l) + Cl 2(g)  C 6 H 5 Cl (s) + HCl (g) When 36.8g C 6 H 6 react with an excess of Cl 2, the actual yield of C 6 H 5 Cl is 38.8g. What is the percent yield?  Given: 36.8g C 6 H 6, excess Cl 2, actual yield=38.8g C 6 H 5 Cl  Unknown: ? g C 6 H 5 Cl, percent yield

Percent Yield example  Methanol can be produced through the rxn of CO and H 2 in the presence of a catalyst.  If 75.0 g of CO reacts to produce 68.4 g CH 3 OH, what is the percent yield?  Answer: 79.7%

Percent Yield example  2ZnS (s) + 3O 2(g)  2ZnO (s) + 2SO 2(g) If the typical yield is 86.78%, how much SO 2 should be expected if 4897 g of ZnS are used?