Stoichiometry Recap

Stoichiometry Recap

Stoichiometry is the process of making predictions/conversions using known numerical relationships.

Numeric relationships you know....

Mole Ratio:
Given the equation: 2 Al2O3 --> 4 Al + 3 O2 ,you can say...

 $\frac{2\ mol\ Al_2O_3}{4\ mol\ Al}\ \ OR\ \ \frac{4\ mol\ Al}{2\ mol\ Al_2O_3}$  

Molar Mass: find/calculate from the periodic table

18.015 g H2O = 1 mol H2O

Multiple Choice

In the equation 2 Al₂O₃ --> 4 Al + 3 O₂, what is the mole ratio of Al to O₂?

• 10 mol Al/ 6 mol O₂

• 3 mol Al/ 2 mol O₂

• 4 mol Al/ 3 mol O₂

• 2 mol Al / 3 mol O₂

Multiple Choice

In the reaction 2 H₂ + O₂ → 2 H₂O what is the mole ratio of O₂ to H₂O

• 1 mol O₂ / 2 mol H₂O

• 2 mol O₂/ 4 mol H₂O

• 3 mol O₂/ 4 mol H₂O

• 4 mol O₂/ 3 mol H₂O

Multiple Choice

The molar mass of table salt (NaCl) is 58.44 g/mol. This is the mass of _____ mol of the substance.

• 4 mol

• 3 mol

• 2 mol

• 1 mol

Multiple Choice

N2 + 3H2 → 2NH3

How many g of H2 are needed to react with 2 moles of N2?

 $2mol\ N_2\ \times\ \frac{\ \ \ \ \ mol\ H_2}{\ \ \ \ \ \ mol\ N_2\ \ }\ \times\frac{\ \ \ \ \ \ \ g\ H_2}{\ \ \ \ \ \ \ mol\ H_2\ }$ 
What should you put in the first fraction?

• mole ratio

• molar mass of H2

• molar mass of H2

Multiple Choice

N2 + 3H2 → 2NH3

How many g of H2 are needed to react with 2 moles of N2?

 $2mol\ N_2\ \times\ \frac{\ \ \ \ \ mol\ H_2}{\ \ \ \ \ \ mol\ N_2\ \ }\ \times\frac{\ \ \ \ \ \ \ g\ H_2}{\ \ \ \ \ \ \ mol\ H_2\ }$ 
What should you put in the second fraction?

• mole ratio

• molar mass of H2

• molar mass of N2

Multiple Choice

2NaClO3 (s) → 2NaCl (s) + 3O2 (g)

How many g of O2 are produced to with 6 moles of NaClO32

 $6mol\ NaClO_3\ \times\ \frac{\ \ \ \ \ mol\ O_2}{\ \ \ \ \ \ mol\ NaClO_3\ \ }\ \times\frac{\ \ \ \ \ \ \ g\ O_2}{\ \ \ \ \ \ \ mol\ O_2\ }$ 
What should you put in the first fraction?

• 3 mol O2/ 2 mol NaClO3

• 31.998g O2 = 1 mol O2

• 90.44 g NaClO3 = 1 mol NaClO3

Multiple Choice

2NaClO3 (s) → 2NaCl (s) + 3O2 (g)

How many g of O2 are produced to with 6 moles of NaClO32

 $6mol\ NaClO_3\ \times\ \frac{\ \ \ \ \ mol\ O_2}{\ \ \ \ \ \ mol\ NaClO_3\ \ }\ \times\frac{\ \ \ \ \ \ \ g\ O_2}{\ \ \ \ \ \ \ mol\ O_2\ }$ 
What should you put in the second fraction?

• 3 mol O2/ 2 mol NaClO3

• 31.998g O2 = 1 mol O2

• 90.44 g NaClO3 = 1 mol NaClO3

Multiple Choice

Cl2 + 2KBr → Br2 + 2KCl

How many mols of Br2 are produced to with 60 g of KBr?

 $60\ g\ KBr\ \times\ \frac{\ \ \ \ \ mol\ KBr}{\ \ \ \ \ \ g\ KBr\ \ }\ \times\frac{\ \ \ \ \ \ \ mol\ Br_2}{\ \ \ \ \ \ \ mol\ KBr}$ 
What should you put in the first fraction?

• 1 mol Br2/ 2 mol KBr

• 159.808 g Br2 = 1 mol Br2

• 119.00 g KBr = 1 mol KBr

Multiple Choice

Cl2 + 2KBr → Br2 + 2KCl

How many mols of Br2 are produced to with 60 g of KBr?

 $60\ g\ KBr\ \times\ \frac{\ \ \ \ \ mol\ KBr}{\ \ \ \ \ \ g\ KBr\ \ }\ \times\frac{\ \ \ \ \ \ \ mol\ Br_2}{\ \ \ \ \ \ \ mol\ KBr}$ 
What should you put in the second fraction?

• 1 mol Br2/ 2 mol KBr

• 159.808 g Br2 = 1 mol Br2

• 119.00 g KBr = 1 mol KBr