Week 25 Quiz: Limiting reactants and % 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

Tags

NGSS.HS-PS1-7

What is the theoretical yield?

• the maximum amount of product from a reaction
• the amount of product recovered from a lab experiment
• amount of product that causes the reaction to stop
• the amount of product needed to reverse the reaction

Tags

NGSS.HS-PS1-7

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

Tags

NGSS.HS-PS1-7

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

Tags

NGSS.HS-PS1-6

What is the arrow in a chemical equation...
H_{2 +} O --> H₂O

• Reactants
• Products 
• Yields/makes
• Chemical Equation 

When 12 moles of O₂ reacts with 1.1 mole of C₁₀H₈ what is the limiting reactant?  C₁₀H₈ + 12 O₂ --> 10 CO₂ + 4 H₂O

• Oxygen
• C₁₀H₈
• Water
• Carbon Dioxide

Tags

NGSS.HS-PS1-7

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

Fe + S --> FeS
Samuel and Liam are working on a chemistry project where they react 7.62g of Fe with 8.67g of S to make grams of FeS. Based on the amounts used, what is the limiting reactant?

(Molar masses: Fe= 55.845g/mol, S= 32.065g/mol, FeS= 87.91g/mol)

• Fe

• S

• FeS

• none 

Tags

NGSS.HS-PS1-7

SO₂ + PCl₅ --> SOCl₂ + POCl₃
How much SOCl₂ is produced when 16.2g SO₂ react with 13.7g PCl_5?  (Molar masses: SO₂= 64g/mol, SOCl₂= 119g/mol, PCl₅=208 g/mol)

Hint: the answer is the smaller calculation

Include Units!

(a)  

Tags

NGSS.HS-PS1-7