![Page 1: SToichiometry. Law of Conservation of Mass Antoine Lavoisier Studied combustion Showed it involved oxygen & life is supported by oxygen in a process similar](https://reader035.vdocuments.us/reader035/viewer/2022062804/5697bfa11a28abf838c9577c/html5/thumbnails/1.jpg)
SToichiometrySToichiometry
![Page 2: SToichiometry. Law of Conservation of Mass Antoine Lavoisier Studied combustion Showed it involved oxygen & life is supported by oxygen in a process similar](https://reader035.vdocuments.us/reader035/viewer/2022062804/5697bfa11a28abf838c9577c/html5/thumbnails/2.jpg)
Law of Conservation of
Mass
Antoine LavoisierStudied combustion
Showed it involved oxygen&life is supported by oxygen
in a process similar to combustion
Carefully weighted reactants & products
In an (ordinary) chemical reaction, mass is neither created nor destroyed.
Wrote first modern chemistry book
Worked as a tax collector during French RevolutionConsidered enemy of the peopleSent to guillotine
![Page 3: SToichiometry. Law of Conservation of Mass Antoine Lavoisier Studied combustion Showed it involved oxygen & life is supported by oxygen in a process similar](https://reader035.vdocuments.us/reader035/viewer/2022062804/5697bfa11a28abf838c9577c/html5/thumbnails/3.jpg)
Law of Conservation of MassAll atoms you start with you end up with
Need to show conservation of mass with balanced equation
Reactant + Reactant --> Product
Combustion:Burning in the presence of oxygen
Heat is evolvedCombustion of hydrocarbonProduces CO2 & Water
Combustion:It is usually easiest to balancecarbon first
hydrogen secondcount how many oxygen needed in products
C5H12 + O2 --> H2O + CO256Need 16 oxygen for products
8
![Page 4: SToichiometry. Law of Conservation of Mass Antoine Lavoisier Studied combustion Showed it involved oxygen & life is supported by oxygen in a process similar](https://reader035.vdocuments.us/reader035/viewer/2022062804/5697bfa11a28abf838c9577c/html5/thumbnails/4.jpg)
Mass-Mass & Mole-Mole Relations in ReactionsSuggested method:
1. write balancedequation
CO + 2 H2 --> CH3OH2. Make Chart
Grams
Molar Mass
Moles have
Given 100.0 g of each reactant,a. which is limiting reactant
b. how much of reactant in excess is leftc. How much product, in grams
100.0 g 100.0 g
28.0 g/mol 2.00 g/mol
______ ______/
//
/
3.57 mol 50.0 mol
3. Pick onetake moles have
& divide by balanced coefficient
This gives you a ratioto multiply other
coefficients by
3.57/1 = 3.57
Moles use 3.57 mol4. Take answer from step 3 multiply other
coefficient by it
3.57 x 2 = 7.14
7.14 mol
Moles left
- -
0 42.9 mol
Grams left 0 85.8 g
3.57 x 1 = 3.57
3.57 mol
32.0 g/mol
114. g
CO85.8 g
114. g
Theoretical yieldPercent yield = (actual yield/ theoretical yield) 100Let’s say you got 100.0 g for this reaction
Percent yield = (100.0 g / 114. g) 100 = 87.7 %
![Page 5: SToichiometry. Law of Conservation of Mass Antoine Lavoisier Studied combustion Showed it involved oxygen & life is supported by oxygen in a process similar](https://reader035.vdocuments.us/reader035/viewer/2022062804/5697bfa11a28abf838c9577c/html5/thumbnails/5.jpg)
You might have your own method for You might have your own method for stoichiometry--that’s fine too.stoichiometry--that’s fine too.