Stoichiometry, Limiting Reagents, and percent yield

When you use a balanced chemical equation to calculate the amount of a product on paper it is referred to as the 

• experimental value
• theoretical value
• true amount
• percent yield

P₄ + 3O₂ --> P₄O₆ 
What is the limiting reactant is 12 moles of P₄ react with 15 moles of O₂?

• P₄
• O₂
• P₄O₆ 
• none of the above

Theoretical yield = 73g
Actual yield = 62g
Calculate the percent yield.

• 1.16%
• 116%
• 85%
• 76%

What is the measured amount of a product obtained from a chemical reaction?

• mole ratio
• theoretical yield
• percentage yield
• actual yield

The limiting reactant

• slows the reaction down
• is used up first
• is the reactant that is left over
• controls the speed of the reaction

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

Identify the limiting reagent when 6.00 g HCl combines with 5.00 g Mg to form MgCl₂.
a.  Mg +  2HCl --> MgCl₂  +  H₂   
b.  a.  Mg +  2HCl --> MgCl₂  +  H₂   

• Mg
• H₂
• MgCl₂
• HCl

Silver nitrate and sodium phosphate are reacted in equal masses of 200 g each. Determine the mass of silver phosphate produced.

3 AgNO₃(aq) + Na₃PO₄(aq) → Ag₃PO₄(s) + 3 NaNO₃(aq)

• 164 g

• 64.0 g

• 146 g

• 54.7 g

3. The reactant that is not completely used up in a chemical reaction is called the __________ .

• spectator reagent
• limiting reagent
• excess reagent
• catalyst

Why is it important to identify the limiting reagent?

• The limiting reagent speeds up the reaction.

• The limiting reagent controls the amount of product formed.

• If there is no limiting reagent, the reaction will not occur.

• No stoichiometry calculations can be done without a limiting reagent.