Limiting Reactants and Percent Yield

When the limiting reactant is used up, what happens?

• the reaction speeds up

• the reaction slows down

• the reaction moves to its 2nd stage

• the reaction stops

What are the correct steps for determining the limiting reactant?

• divide each reactant by its molar mass and look for the smallest number

• balance the chemical equation and look for the smallest coefficient

• divide the moles of each reactant by its coefficient and look for the smallest number

• divide each reactant by Avogadro's number and look for the smallest number

Tags

NGSS.HS-PS1-7

True or False?
A chemical reaction stops before the limiting reagent is used up.

• True

• False

Tags

NGSS.HS-PS1-7

When does a reaction stop?

• When it wants to

• When both the limiting and excess reactants are gone

• When all the excess reactant has been consumed

• When all the limiting reactant has been consumed

What is the limiting reactant if 10 moles of NH₃  react  with 30.0 moles of NO?
4NH₃+6NO --> 5N₂ + 6H₂O

• NH₃

• NO

• N₂

• water

Tags

NGSS.HS-PS1-7

What is the limiting reactant if 15 moles of NH₃  react  with 16 moles of NO?
4NH₃+6NO --> 5N₂ + 6H₂O

• NH₃

• NO

• N₂

• water

Tags

NGSS.HS-PS1-7

What is the limiting reactant if 15 GRAMS of NH₃ react with 16 GRAMS of NO?
4NH₃+6NO --> 5N₂ + 6H₂O
(Remember, convert grams to moles, then divide each substance by the number of moles given as the coefficient from the balanced chemical equation).

• NH₃ is the limiting because the reaction only requires 0.22 mol of NH₃

• NO is the limiting reactant because the reaction only requires 0.088 mol NO 

• NH₃ is the limiting because the reaction only requires 0.88 mol of NH₃

• NO is the limiting reactant because the reaction only requires 0.53 mol NO 

Tags

NGSS.HS-PS1-7

To determine the limiting reactant in a chemical reaction, one must know the

• amount of product formed

• available amount of one of the reactants

• available amount of each of each reactant

• speed of the reaction

A chemical reaction involving substances A and B stops when B is completely used.  B is the

• excess reactant

• primary reactant

• limiting reactant

• primary product

• A

• B

• C

• Cannot be determined