Unit 6: Stoichiometry

Which of the following is a correct interpretation of this equation?    
2 Al(s)  +  3 CuSO₄(aq)  -->  Al₂(SO₄)₃(aq)  +  3 Cu(s)

• a)  2 grams Al and 3 grams CuSO₄ react to form 1 gram Al₂(SO₄)₃ and 3 grams Cu
• a)  2 atoms Al and 3 molecules CuSO₄ react to form 1 molecule of Al₂(SO₄)₃ and 3 atoms Cu
• a)  2 moles Al and 3 moles CuSO₄ react to form 1 mole of Al₂(SO₄)₃ and 3 moles Cu
• a)  both b and c are correct

Using the following equation:
Fe₂O₃(s) + 3H₂(g) → 2Fe(s) + 3H₂O(l)
How many moles of iron can be made from  6 moles H₂? 

• 4 moles Fe
• 6 moles Fe
• 9 moles Fe
• 2 moles Fe

N₂ +  3H₂ → 2NH₃ 
How many moles of hydrogen are needed to react with 2 moles of nitrogen?

• 6 mol H

• 2 mol H

• 3 mol H

• 1 mol H

B₂H₆ + 3O₂ -->2 HBO₂ + 2 H₂O
 What mass of O₂ will be needed to react with 36.1 g of B₂H₆?

• 13.8 g O₂
• 3.86 mol of O₂
• 124 g O₂

4 Al + 3 O₂ –> 2 Al₂O₃ 

How many moles of aluminum would be needed to completely react with 45 grams of O₂?

• 1.05 moles
• 3.75 moles
• 1.875 grams
• 1.875 moles

Mg(s) + 2 HCl(aq)  -->  MgCl₂(aq)   + H₂(g)
How many moles of HCl are consumed in the production of 7.5 moles of MgCl₂?

• 3.8 moles
• 15 moles
• 7.5 moles
• 23 moles

 CaC₂(s) + 2H₂O(l)   -->   C₂H₂(g)   + Ca(OH)₂(aq)
how many grams of Ca(OH)₂ would be formed with 3.20 moles of CaC₂?

• 119 g
• 21.2 g
• 114 g
• 237 g

Using the following equation:
4NH₃(g) + 5O₂(g) --> 4NO(g) + 6H₂O(l)
How many grams of oxygen gas are needed to react with 56.8 grams of NH₃?

• 45.08 g O₂
• 133.33 g O₂
• 260.77 g O₂
• 75.92 g O₂

Fe (s) + S (l) --> FeS (s)  

In the experiment above, 7.62 g of Fe are allowed to react with 8.67 g of S.
How many grams of FeS are formed?

• 14.8 g
• 12.2 g
• 13.7 g
• 19.9 g

When does a chemical reaction stop?

• When the lab is finished
• When the excess reactant is used up
• When the limiting reactant is used up
• Chemical reactions never stop