Unit 7 Review - Moles & Stoichiometry

Stoichiometry is -

• a balanced reaction with the same number of elements on both sides of the reaction

• Calculating moles

• using the balanced reaction and moles to calculate amounts needed and used

• percentage yield

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

What is the first thing you must do to solve a stoichiometry problem?

• Write a Balanced Equation
• Panic
• Write an Unbalanced Equation
• Ask for help

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

You need 2 pieces of bread, 1 tablespoon of peanut butter and 2 tablespoons of jelly to make a sandwich.  If you have 10 pieces of bread, 4 tablespoons of peanut butter and 20 tablespoons of jelly, what is the limiting reactant?

• bread
• jelly
• peanut butter
• sandwich

In the lab, a scientist calculated that he should produce 12.3 grams of product in his experiment. When he is finished collecting the product it weighs 10.1 grams. What is his percent yield?

• 82%

• 0.82%

• 10.1 %

• 100%

The type of stoichiometry problem that involves the most steps is a 

• mass-to-mole conversion
• mole-to-mass conversion
• mass-to-mass conversion
• mole-to-mole conversion

If the percentage yield for a chemical reaction is 80.0%, the 

• actual yield is 80.0g for every theoretical yield of 100g.
• actual yield is 80 times as much as the theoretical yield.
• theoretical yield is 80 times as much as the actual yield. 
• theoretical yield is 80.0 g for every actual yield of 100g.

Which of the following is NOT true about limiting and excess reagents?

• The amount of product obtained is determined by the limiting reagent.
• Some of the excess reagent is left over after the reaction is complete. 
• A balanced equation is necessary to determine which reactant is the limiting reagent.
• The reactant that has the smallest given mass is the limiting reagent. 

When you are converting units, how do you set up your conversion factor?

• The units you have on the top and the units you want on the bottom
• The units you want on the top and the units you have on the bottom