Stoichiometry Steps

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

• True

• False

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

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

In a balanced equation, the ratio between the coeffients of any two substances is called the _______.

• mole ratio

• stoichiometry

• limiting reactant

• excess reactant

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

The coefficients in a chemical equation represent the

• number of atoms in each compound in a reaction

• relative numbers of moles of reactants and products

• masses, in grams, of all reactants and products

• number of valence electrons involved in the reaction

Tags

NGSS.HS-PS1-7

Mole ratios are obtained from the ________________.

• balanced chemical equation

• molar masses

• periodic table

• subscripts

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

• find the excess reactant

• find the limiting reactant

• find the empirical formula

• write a balanced chemical equation

How do you determine the limiting reactant?

• Find the amount of product produced by each amount of reactant. The reactant that makes the most is the limiting reactant.

• Find the amount of product produced by each amount of reactant. The reactant that makes the least is the limiting reactant.

• The reactant with the least amount of mass (grams) present is the limiting reactant.

• Cannot be determined.

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