Stoichiometry-Level 2 Problems (Limiting Reactant & Percent Yield)

The reactant that controls the amount of product formed in a chemical reaction is called the what?

Limiting reactant

In a chemical reaction the reactant renaming after all of the limiting reactant is used is known as the what?

Excess reactant

How do you determine which reactant is limiting?

1) The chemical that makes the least amount of product is the limiting reactant.

2) You can also compare the mole ratios of the reactants in the balanced equation to mole ratios given in the reaction itself.

2) You can recognize limiting reactant problems because they will give you 2 amounts of chemical.

In a chemical reaction the limiting reactant...

Would be completely used first

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

Available amounts of both reactants

In the reaction A+B > C+D if there is an insufficient quantity of B to completely react with all of A then...

B is the limiting reactant

What is Yield?

Yield is the amount of product made in a chemical reaction.

How many types of Yield?

There are three types of Yield:

1)Actual yield- what you actually get in the lab when the chemicals are mixed.

2)Theoretical yield- what the balanced equation tells should be made.

3)Percent Yield:(Actual/Theoretical)x100

theoretical yield

the maximum product that is able to be produced from a reactant in the chemical reaction taking place

actual Yield

The actual amount of product produced after a chemical reaction

percent yield

experimental value/theory (x100)

The maximum amount of a product that can be produced from a given amount of reactant is called...

Theoretical yield

In most chemical reactions the amount of product obtained is...

Less than the theoretical yield

A chemist interested in the efficiency of a chemical reaction would need to calculate the...

Percent yield

In percent yield, what it tells us about the reaction?

In percent yield, it tells us how efficient a reaction is.

Should percent yield be bigger than 100%?

No percent yield should not be bigger than 100%.

Theoretical yield should ______ be larger than actual yield.

Always

What is the maximum number of grams of PH₃ that can be formed when 6.2 g of phosphorus reacts with 4.0 g of hydrogen to form PH₃?

6.8 g

Methane and hydrogen sulfide form when hydrogen reacts with carbon disulfide. Identify the excess reagent and calculate how much remains after 36 L of H₂ reacts with 12 L of CS₂.

3.0 L CS₂

Lead nitrate can be decomposed by heating. What is the percent yield of the decomposition reaction 2 if 9.9 g Pb(NO₃)₂ are heated to give 5.5 of PbO?

82%

Hydrogen gas is produced when zinc reacts with hydrochloric acid. If actual yield of this reaction is 85%, how many grams of zinc are needed to produce 113 g H₂?

380 g

a) Write the balanced equation for the reaction between magnesium and nitric acid that produces magnesium nitrate and hydrogen gas.

b) Type of reaction: __________________________

c) If I start this reaction with 40 grams of magnesium and an excess of nitric acid, how many grams of hydrogen gas will I produce?

d) If 1.7 grams of hydrogen is actually produced, what was my percent yield of hydrogen?

a) Mg + 2HNO₃ → Mg(NO₃)₂ + H₂

b) Type of reaction: single displacement

c) 3.3 grams (when Mg atomic mass = 24.3 grams)

d) 52%

a) Write the balanced equation for the decomposition of sodium bicarbonate into sodium hydroxide and carbon dioxide.

b) Type of reaction: __________________________

c) If 25 grams of carbon dioxide gas is produced in this reaction, how many grams of sodium hydroxide should be produced?

d) If 50 grams of sodium hydroxide are actually produced, what was my percent yield?

1 NaHCO₃ → 1 NaOH + 1 CO₂

Type of reaction: decomposition

22.7 grams NaOH

50/22.7 x 100% = 220%

3 NH₄NO₃ + Na₃PO₄ → (NH₄)₃PO₄ + 3 NaNO₃

Assuming we started with 30 grams of ammonium nitrate and 50 grams of sodium phosphate, which is the limiting reagent? How many grams of sodium nitrate are produced?

ammonium nitrate

31.9 grams of sodium nitrate

When copper (II) chloride reacts with sodium nitrate, copper (II) nitrate and sodium chloride are formed.

If 15 grams of copper (II) chloride react with 20 grams of sodium nitrate, how much sodium chloride can be formed?

CuCl₂ + 2 NaNO₃ → Cu(NO₃)₂ + 2 NaCl

13.0 grams NaCl

Complete and balance the partial equation

CaO(s)+CO₂(g) →

and calculate the total mass of CaO(s) that reacts completely with 88 grams of CO₂ to produce 200 grams of CaCO₃(s).

112 g

Given the balanced equation representing a reaction

2NaCl(l)→ 2Na(l)+Cl₂(g)

A 1,170. g sample of NaCl(l) completely reacts, producing 460. grams of Na(l). What is the total mass of Cl₂(g) produced?

710. g

How many grams of aluminum sulfate are produced if 23.33 g Al reacts with 74.44 g CuSO₄?

2Al (s) + 3CuSO₄ (aq) --> Al₂(SO₄)₃ (aq) + 3Cu (s)

CuSO₄ is the limiting reagent

53.23 g Al₂(SO₄)₃ produced

Consider the following reaction:

NH₄NO₃ + Na₃PO₄ → (NH₄)₃PO₄ + NaNO₃

a) Which reactant is limiting, assuming we started with 30.0 grams of ammonium nitrate and 50.0 grams of sodium phosphate.

b) How many grams of ammonium phosphate are produced?

a) Sodium Phosphate

b) 45.5 g of ammonium phosphate (0.305 mol)

Write the balanced equation for the reaction given below:

CuCl₂ + NaNO₃ → Cu(NO₃)₂ +NaCl

a) If 15. grams of copper (II) chloride react with 20. grams of sodium nitrate, how many grams of sodium chloride can be formed?

b) What is the limiting reactant?

c) How much of the excess reactant is left over in this reaction?

CuCl₂ + 2NaNO₃ → Cu(NO₃)₂ +2NaCl

a) 13 g of NaCl

b) Copper(II) chloride

c) 1.0 g is left