Stoichiometry terms

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

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

3 Mg + 1 Fe₂O₃ → 3 MgO + 2 Fe
What is the Ratio of moles of Mg to moles Fe?

• 3mol Mg / 2 mol Fe
• 2 mol Mg/ 3 mol Fe
• 1 mol Fe/ 2 mol Fe
• 3 mol MgO / 2 mol Fe

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

Which of the following is true of the law of conservation of mass?

• The same number and type of each atom will always be present before and after a chemical reaction takes place.
• Some of the atoms present before the reaction will always be lost during a chemical reaction.
• Some of the atoms will always be changed into a different type of atom by a chemical reaction.
• During a chemical reaction, atoms will always be combined into much larger molecules.

Tags

NGSS.HS-PS1-7

The excess reactant is not completely used up during the reaction.

• True

• False

Tags

NGSS.HS-PS1-7

The ______________ yield is the maximum amount of product possible in a reaction. This determines the amount of product that should be produced in a perfect setting

• Percent
• actual
• stoichiometry
• theoretical

What does percent yield indicate?

• The amount of product we should get
• The efficiency of the lab
• The amount of product we actually got
• nothing