Presentation on theme: "Stoichiometry Chemical Reactions and Quantities"— Presentation transcript:
1Stoichiometry Chemical Reactions and Quantities Mole Relationships in Chemical EquationsMole-MoleMole-GramsGrams-GramsTheoretical Yield% YieldLimiting Reactants
2Mole-Mole Factors Write and balance the equation Show the mole-to-mole ratio between two of the substances in a balanced equationUse the coefficients of two substances in the balanced equation
3Writing Mole Factors 4 Fe + 3 O2 2 Fe2O3 Fe and O mole Fe and 3 mole O23 mole O mole FeFe and Fe2O3 4 mole Fe and 2 mole Fe2O32 mole Fe2O3 4 mole FeO2 and Fe2O3 3 mole O2 and 2 mole Fe2O32 mole Fe2O3 3 mole O2
4Mole Factor 3 H2(g) + N2(g) 2 NH3(g) A. A mole factor for H2 and N2 is 1) 3 mole N ) 1 mole N ) 1 mole N21 mole H mole H mole H2B. A mole factor for NH3 and H2 is1) 1 mole H ) 2 mole NH ) 3 mole N22 mole NH mole H mole NH3
5Solution 3 H2(g) + N2(g) 2 NH3(g) A. A mole factor for H2 and N2 is 2) 1 mole N23 mole H2B. A mole factor for NH3 and H2 is2) 2 mole NH3
6Chemical Calculations 4 Fe O Fe2O3How many moles of Fe2O3 are produced when 6.0 moles O2 react?
7Chemical Calculations 4 Fe O Fe2O3How many moles of Fe2O3 are produced when 6.0 moles O2 react?6.0 mole O2 x 2 mole Fe2O3 = 4.0 mole Fe2O33 mole O2
8Mole Ratio Calculations 4 Fe O Fe2O3How many moles of Fe are needed to react with 12.0 mole of O2?1) mole Fe2) mole Fe3) mole Fe
9Solution 4 Fe + 3 O2 2 Fe2O3 12.0 mole O2 x 4 mole Fe = 16.0 mole Fe
10Mole Ratio/Grams Calculations 4 Fe O Fe2O3How many grams of O2 are needed to produce mole of Fe2O3?1) g O22) g O23) g O2
12Solution Combined2) g O20.400 mole Fe2O3 x 3 mole O2 x g O22 mole Fe2O3 1 mole O2= g O2
13Mass of A ReactionThe reaction between H2 and O2 produces 13.1 g of water. How many grams of O2 reacted?Write the equationH2 (g) O2 (g) H2O (g)
14Mass of A ReactionThe reaction between H2 and O2 produces 13.1 g of water. How many grams of O2 reacted?Write the equationH2 (g) O2 (g) H2O (g)Balance the equation
15Mass of A ReactionThe reaction between H2 and O2 produces 13.1 g of water. How many grams of O2 reacted?Write the equationH2 (g) O2 (g) H2O (g)Balance the equation2 H2 (g) O2 (g) 2 H2O (g)
16Organize datamole bridge2 H2 (g) O2 (g) 2 H2O (g)? g gPlan g H2O mole H2O mole O O2Setup
17Organize data mole bridge 2 H2 (g) + O2 (g) 2 H2O (g) ? g 13.1 g Plan g H2O mole H2O mole O O2Setup13.1 g H2O x 1 mole H2O x 1 mole O2 x g O g H2O 2 mole H2O 1 mole O2= g O2
18Points to Remember 1. Read an equation in moles 2. Convert given amount to molesUse mole factor to give desiredmoles4. Convert moles to gramsgrams (given) grams (desired)moles (given) moles (desired)
19Stoichiometric Calculations How many grams of O2 are need to react grams of Na in the reaction4 Na O Na2OComplete the set up:50.0 g Na x 1 mole Na x ________ x _______23.0 g Na
20Solution4 Na O Na2O50.0 g Na x 1 mole Na x 1 mole O2 x g23.0 g Na mole Na mole O2= g O2
21Stoichiometric Calculations 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 + O CO2 + H2O
22Solution 2 C2H2 + 5 O2 4 CO2 + 2 H2O = 22.2 g C2H2 75.0 g CO2 x 1 mole CO2 x 2 mole C2H2 x 26.0 g C2H244.0 g CO mole CO mole C2H2= g C2H2
23Calculations with Equations Stoichiometry Part 2Calculations with EquationsLimiting ReactionsPercent Yield
24StoichiometryHow many O2 molecules will react with 505 grams of Na to form Na2O?4 Na O Na2OComplete the set up:505 g Na x 1 mol Na x ________ x _______23.0 g Na
25Solution 4 Na + O2 2 Na2O 505 g Na x 1 mol Na x 1 mol O2 x 6.02 x 1023 23.0 g Na mol Na 1 mol O2= x 1024 molelcules
26Limiting ReactantsIf the amounts of two reactants are given, the reactant used up first determines the amount of product formed.
27So, you want to work for a sandwich shop? Suppose you are preparing cheese sandwiches. Each sandwich requires 2 pieces of bread and 1 slice of cheese. If you have 4 slices of cheese and 10 pieces of bread, how many cheese sandwiches can you make?
29Sandwich Stoichiometry How many sandwiches can you make?____ slices of bread+ ____ slices of cheese= ____ sandwichesWhat is left over? ________________What is the limiting reactant?
30Solution How many sandwiches can you make? __10__ slices of bread + __4__ slices of cheese= __4__ sandwichesWhat is left over? _2 slices of breadWhat is the limiting reactant? cheese
31Hints for Limiting Reactant Problems 1. For each reactant amount given, calculate themoles (or grams) of a product it could produce.2.The reactant that produces the smaller amount of product is the limiting reactant.3. The number of moles of product produced by the limiting reactant is ALL the product possible. There is no more limiting reactant left.
32Percent YieldYou prepared cookie dough to make 5 dozen cookies. The phone rings while a sheet of 12 cookies is baking. You talk too long and the cookies burn. You throw them out (or give them to your dog.) The rest of the cookies are okay.How many cookies could you have made (theoretical yield)?How many cookies did you actually make to eat? (Actual yield)
33Key PhrasesActual yield is the amount of product actually recovered from an experimentTheoretical (possible) yield is the maximumamount of product that could be produced fromthe reactant.Percent Yield is the actual yield compared to the maximum (theoretical yield) possible.
34Calculating Percent Yield What is the percent yield of cookies?Percent Yield = Actual Yield (g) recovered X Possible Yield (g)% cookie yield = cookies x 100 = 80% yield60 cookies