2 H2 + O2 → 2 H2O 2 mol H2 for every 1 mol O2 Mol to Mol Ratios In chemical calculations, mol ratios convert moles of one substance to moles of another substance. mol ratio: coefficients of a balanced equation 2 H2 + O2 → 2 H2O 2 mol H2 for every 1 mol O2

2 H2 + O2 → 2 H2O OR 2 mol H2 for every 2 mol H2O Mol to Mol Ratios In chemical calculations, mol ratios convert moles of one substance to moles of another substance. mol ratio: coefficients of a balanced equation 2 H2 + O2 → 2 H2O OR 2 mol H2 for every 2 mol H2O

2 H2 + O2 → 2 H2O OR 1 mol O2 for every 2 mol H2O Mol to Mol Ratios In chemical calculations, mol ratios convert moles of one substance to moles of another substance. mol ratio: coefficients of a balanced equation 2 H2 + O2 → 2 H2O OR 1 mol O2 for every 2 mol H2O

2 H2 + O2 → 2 H2O There are 6 mol to mol ratios that can be written from this balanced equation: 2 mol H2 1 mol O2 2 mol H2O 1 mol O2 2 mol H2 2 mol H2 2 mol H2O 2 mol H2O 1 mol O2 To determine the number of moles in a sample of a compound, first measure the mass of the sample. Then use the molar mass to calculate the number of moles in that mass. 4

We must use MOLES to calculate, but… We don’t measure moles in the lab, we measure mass (in grams), but… We can’t convert grams A to grams B, so… We convert grams to moles using… Molar Mass (g/mol) from… the Periodic Table To determine the number of moles in a sample of a compound, first measure the mass of the sample. Then use the molar mass to calculate the number of moles in that mass.

In a typical stoichiometric problem: 1) Convert grams to moles (if necessary) using the molar mass (from PT) 2) Convert moles (given) to moles (wanted) using the mol ratio (from coefficients) 3) Convert moles to grams (if necessary) 1 mol A . grams A _ mol B mol A grams B 1 mol B grams A x x x = 1) molar mass 2) mole ratio 3) molar mass

Mg + 2 HCl → MgCl2 + H2 4.0 mol Mg x Moles to Moles (Calculation #1) Handout: 4 Types of Stoichiometric Calculations Moles to Moles (Calculation #1) How many moles of hydrogen gas (H2) are produced from 4.0 mol Mg? Mg + 2 HCl → MgCl2 + H2 4.0 mol Mg x 7

2) moles (given) to moles (wanted) using the mol ratio 1) grams to moles using the molar mass 2) moles (given) to moles (wanted) using the mol ratio 3) moles to grams 1 mol A . grams A _ mol B mol A grams B 1 mol B grams A x x x = 1) molar mass 2) mole ratio 3) molar mass (coefficients)

Mg + 2 HCl → MgCl2 + H2 1 mol H2 1 mol Mg 4.0 mol Mg x = 4.0 mol H2 Handout: 4 Types of Stoichiometric Calculations Moles to Moles (Calculation #1) How many moles of hydrogen gas (H2) are produced from 4.0 mol Mg? Mg + 2 HCl → MgCl2 + H2 1 mol H2 1 mol Mg 4.0 mol Mg x = 4.0 mol H2 mol ratio 9

Mg + 2 HCl → MgCl2 + H2 4.0 mol HCl x Moles to Moles (Calculation #1) How many moles of hydrogen gas (H2) are produced from 4.0 mol HCl? Mg + 2 HCl → MgCl2 + H2 4.0 mol HCl x 10

2) moles (given) to moles (wanted) using the mol ratio 1) grams to moles using the molar mass 2) moles (given) to moles (wanted) using the mol ratio 3) moles to grams 1 mol A . grams A _ mol B mol A grams B 1 mol B grams A x x x = 1) molar mass 2) mole ratio 3) molar mass (coefficients)

Mg + 2 HCl → MgCl2 + H2 1 mol H2 2 mol HCl 4.0 mol HCl x = 2.0 mol H2 Moles to Moles (Calculation #1) How many moles of hydrogen gas (H2) are produced from 4.0 mol HCl? Mg + 2 HCl → MgCl2 + H2 1 mol H2 2 mol HCl 4.0 mol HCl x = 2.0 mol H2 mol ratio 12

Mg + 2 HCl → MgCl2 + H2 Moles to Grams (Calculation #2) How many grams of H2 are produced from 4.00 mol HCl? Mg + 2 HCl → MgCl2 + H2 4.00 mol HCl x 13

(coefficients) (from PT) 1) grams to moles using the molar mass 2) moles (given) to moles (wanted) using the mol ratio 3) moles to grams 1 mol A . grams A _ mol B mol A grams B 1 mol B grams A x x x = 1) molar mass 2) mole ratio 3) molar mass (coefficients) (from PT)

Mg + 2 HCl → MgCl2 + H2 mol ratio molar mass Moles to Grams (Calculation #2) How many grams of H2 are produced from 4.00 mol HCl? Mg + 2 HCl → MgCl2 + H2 1 mol H2 2 mol HCl 2.02 g H2 1 mol H2 4.00 mol HCl x x = 4.04 g H2 mol ratio molar mass 15

Mg + 2 HCl → MgCl2 + H2 Grams to Moles (Calculation #3) How many mol of H2 are produced from 48 g Mg? Mg + 2 HCl → MgCl2 + H2 48 g Mg x 16

(from PT) (coefficients) 1) grams to moles using the molar mass 2) moles (given) to moles (wanted) using the mol ratio 3) moles to grams 1 mol A . grams A _ mol B mol A grams B 1 mol B grams A x x x = 1) molar mass 2) mole ratio 3) molar mass (from PT) (coefficients)

Mg + 2 HCl → MgCl2 + H2 molar mass mol ratio Grams to Moles (Calculation #3) How many mol of H2 are produced from 48 g Mg? Mg + 2 HCl → MgCl2 + H2 1 mol Mg 24.31 g Mg 1 mol H2 1 mol Mg 48 g Mg x x = 2.0 mol H2 molar mass mol ratio 18

Mg + 2 HCl → MgCl2 + H2 Grams to Grams (Calculation #4) How many grams of H2 are produced from 18 g HCl? Mg + 2 HCl → MgCl2 + H2 18 g HCl x 19

(from PT) (coefficients) (from PT) 1) grams to moles using the molar mass 2) moles (given) to moles (wanted) using the mol ratio 3) moles to grams 1 mol A . grams A _ mol B mol A grams B 1 mol B grams A x x x = 1) molar mass 2) mole ratio 3) molar mass (from PT) (coefficients) (from PT)

Mg + 2 HCl → MgCl2 + H2 mol ratio molar mass molar mass Grams to Grams (Calculation #4) How many grams of H2 are produced from 18 g HCl? Mg + 2 HCl → MgCl2 + H2 1 mol HCl 36.46 g HCl 1 mol H2 2 mol HCl 2.02 g H2 1 mol H2 18 g HCl x x x = 0.50 g H2 mol ratio molar mass molar mass 21

C2H5OH(l) + 3 O2(g)  2 CO2(g) + 3 H2O(g) Quick Quiz! 1. How many moles of water are produced from burning 4.00 mol C2H5OH (ethanol)? C2H5OH(l) + 3 O2(g)  2 CO2(g) + 3 H2O(g) 3.00 mol H2O 4.00 mol H2O 12.0 mol H2O 1.33 mol H2O mol ratio 3 mol H2O 1 mol C2H5OH 4.0 mol C2H5OH x =

C2H5OH(l) + 3 O2(g)  2 CO2(g) + 3 H2O(g) Quick Quiz. 2. How many grams of oxygen gas (O2) are needed to react with 2.00 mol of C2H5OH ? C2H5OH(l) + 3 O2(g)  2 CO2(g) + 3 H2O(g) 6.00 g O2 21.1 g O2 96.0 g O2 192 g O2 molar mass mol ratio 3 mol O2 . 1 mol C2H5OH 2.0 mol C2H5OH x 32.00 g O2 1 mol O2 x =