Unit 7 Stoichiometry

Fill in the Blanks

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

Multiple Choice

How many moles of KClO3 must decompose in order to produce 9 moles of O2?

• 3 moles

• 6 moles

• 9 moles

• 12 moles

Multiple Choice

How many moles of CO2 is required to produce 5 moles of O2?

• 2 moles

• 5 moles

• 6 moles

• 10 moles

Multiple Choice

2 NaClO₃ (s) --> 2NaCl (s) +3 O₂ (g)

12.00 moles of NaClO₃ will produce how many grams of O₂?

• 256 g of O₂

• 576 g of O₂

• 288 g O₂

Multiple Choice

How many grams of silver will be formed from 12.0 grams of copper?

• 20.4 g

• 30.5 g

• 40.8 g

• 50.0 g

Multiple Choice

The diagram below represents H₂ and Cl₂ molecules that will potentially react to form HCl. Which of the following best describes this reaction?

• The limiting reactant is chlorine.

• The limiting reactant is hydrogen.

• Hydrogen and chlorine are nonreactive.

• All molecules shown will react to form the product. 

Multiple Choice

What kind of ratio is represented when having one hot dog in one bun?

• 1:1

• 2:1

• 3:1

• 1:2

Multiple Choice

Identify the limiting and excess reactants in the reaction shown.

• N₂ is limiting and H₂ is excess. 

• H₂ is limiting and N₂ is excess. 

• NH₃ is both limiting and excess.

• There is no limiting reactant. 

Multiple Choice

Hydrogen and oxygen molecules combine to form water molecules as shown in the reaction below. Given the molecules provided, which of the following is true about the products of this reaction? 

• 2 H₂O molecules are produced, O₂ is the limiting reactant

• 4 H₂O molecules are produced, H₂ is the limiting reactant

• 4 H₂O molecules are produced, O₂ is the limiting reactant

• 6 H₂O molecules are produced, H₂ is the limiting reactant

Multiple Choice

A reaction $$2A + 4B \rightarrow 3C$$ is set up with 8 moles of A and 8 moles of B. Calculate the amount of C produced and identify the excess reactant.

• 12 moles of C, A is in excess

• 12 moles of C, B is in excess

• 6 moles of C, A is in excess

• 6 moles of C, B is in excess

Multiple Choice

4Si₂H₃ + 11O₂ <=> 8SiO₂ + 6H₂O

Millie reacts 30g of Disilicon Trihydride (Si₂H₃) with an excess of Oxygen gas and produces 70g of Silicon Dioxide (SiO₂). This doesn't match her calculations however. What is Millie's percent yield?

• 100%

• 87%

• 49%

• 115%

Multiple Choice

What is the formula for calculating percent yield?

• Percent yield = Actual yield x 100%

• Percent yield = Theoretical yield x 100%

• Percent yield = Actual yield / Theoretical yield x 100%

• Percent yield = Theoretical yield / Actual yield x 100%

Multiple Choice

If 23 g KCl are obtained,

what is the percent yield for the reaction?

• 44%

• 102%

• 98%

• 43%

Multiple Choice

When reacting Na with Cl₂, we calculated that the theoretical yield should be 13 grams. Our actual yield was 12.5 grams. What is the percent yield?

• 90.4%

• 104%

• 96.15%

• 1.04%

Fill in the Blanks

The theoretical yield of a reaction is 237 grams, but the reaction actually yields 26 less grams than expected. What is the percent yield?

Fill in the Blanks

P₄ + 6Cl₂ --> 4PCl₃  The reaction of 75.0g P₄ with excess chlorine gas produces 110g PCl₃ in lab. Find the theoretical yield and calculate percent yield for the reaction.  Round to nearest whole number. DO NOT TYPE IN PERCENT SIGN!

Molar mass P₄ = 123. 9 g/mol

Molar Mass PCl₃ = 137.3 m/mol

Poll

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