Coefficient = the number of moles
Ex) 2 HgO => 2Hg + O2 means 2 mol HgO, 2 mol Hg, and 1 mol O2
Mole Ratio: ratio based on coefficients from any 2 substances in a balanced equation
Ex) 2 HgO => 2Hg + O2 means 2 mol HgO
1 mol O2
Slide 3
Type 1: Mole to Mole
Multiply the number of moles in the problem by the mole ratio, keeping like units diagonal from each other.
Example problem: Find the number of moles Al2(SO4)3 produced from 15 mol Al
2Al + 3H2SO4 => Al2(SO4)3 + 3H2
Slide 4
Type 4: Gram to Gram
Steps:
1: Use the mass of one mole of the element to find the # of moles
2: Use mole ratio to find # of moles of second element
3: Use the mass of one mole of the element to find mass of that piece
2Al2O3 => 4Al + 3O2
Ex) How many grams Al2O3 are needed to produce 79.5 grams O2?
Slide 5
Limiting Reactant
Using stoichiometry to find how much product each reactant makes, and the one that makes less product is the limiting reactant
USE MOLE RATIO TO FIND HOW MUCH PRODUCT IS BEING MADE.
Example problem:
If 2.8 mol of Calcium Hydroxide are used to neutralize 6.3 mol of Hydrochloric Acid, which one will be the limiting reactant?
Ca(OH)2 + 2HCl => CaCl2 + 2HOH
Slide 6
Percent Yield
Stoichiometry is the ideal world yield, but we don't live in an ideal world.
Given product/amount = actual yield
Stoich answer = theoretical yield
If stoich answer isn't given, FIND IT.
Formula: actual/theoretical x 100 = % yield
2As2O3 + 3C => 3CO2 + 4As
Example: 4.6 moles of CO2 was supposed to be made, but only 3.9 moles of CO2 was recovered.