Moles, Stoichiometry and Limiting and Excess Reagent

The limiting reactant . . .

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

Use the equation 2 Al + 3 Cl₂ ---> 2 AlCl₃.  If 2 moles of aluminum and 2 moles of chlorine are reacted, identify the limiting reactant.

• AlCl₃
• Cl₂
• Al
• None

1. What is a limiting reagent?

• any reactant used up first in a reaction.
• any reactant left over at the end of a reaction.
• the maximum amount of product formed from a given amount of reactant.
• the purity of the reactant.

1 Cheese + 2 Bread --> 1 Grilled cheese
How many grilled cheeses can you make with 26 slices of bread and 14 pieces of cheese?

• 14
• 13
• 26
• 7

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

• spectator reagent

• limiting reagent

• excess reagent

• catalyst

When 12 moles of O₂ reacts with 6 moles of C₁₀H₈, what is the limiting reactant?  
1 C₁₀H₈ + 12 O₂ --> 10 CO₂ + 4 H₂O

• Oxygen
• C₁₀H₈
• Water
• Carbon Dioxide

Identify the limiting reagent when 6.00 moles HCl combines with 5.00 moles Mg to form MgCl₂.
 
1 Mg +  2 HCl --> 1 MgCl₂  +  1 H₂   
 

• Mg
• H₂
• MgCl₂
• HCl

Which reactant is the limiting reagent and why?

2H₂(g) + O₂(g) → 2H₂O(l)

• Hydrogen is the limiting reagent because two moles of hydrogen is required for every one mole of oxygen to produce two water.

• Oxygen is the limiting reagent because two moles of hydrogen is required for every one mole of oxygen to produce two water.

4NH₃ + 5O₂ --> 4NO + 6H₂O

How many Liters of NO are formed if 6.30g of ammonia react with 1.80g of oxygen?

• 1.5 L

• 2.02 L

• 1.01 L

• 8.30 L

The limiting reactant

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

Answer explanation

the limiting is used up first and stops/limits the reaction from continuing.