Stoichiometry - Online Tutor, Practice Problems & Exam Prep

Alkaline batteries are used in most household items. The overall cell reaction is: 

Zn(s) + 2 MnO₂(s) ⇌ ZnO(s) + Mn₂O₃(s)

Calculate the mass of ZnO produced from 6.25×10^–2 g of MnO₂.

Bleaching of hair usually involves the reaction of hydrogen peroxide (H₂O₂) with the melanin (C₁₈H₁₀N₂O₄) in hair. As the bleaching solution is rubbed to hair, melanin is oxidized by hydrogen peroxide: C₁₈H₁₀N₂O₄ + 34 H₂O₂ → 2 NH₃ + 36 H₂O + 18 CO₂. A bleaching solution contains 9% H₂O₂ by mass. If 20 g of the bleaching solution is used, calculate the mass (in mg) of melanin that is oxidized.

In a laboratory, a student accidentally spills 300 g of glacial acetic acid (CH₃CO₂H) which is 99.5% acetic acid by mass. Calculate the mass (in g) of sodium bicarbonate required to neutralize the spill.

A vat containing 5 kg of acetic acid was accidentally spilled over a number of marble blocks. Acetic acid reacts with the calcite (CaCO₃) in marble: CaCO₃(s) + CH₃CO₂H(aq) → (CH₃CO₂)₂Ca(aq) + CO₂(g) + H₂O(l). If the marble blocks have a mass of 100 g, determine the number of blocks that was damaged. Assume the blocks are made of pure calcite and it is considered damaged if 5.0% of its mass reacted.

Decane (C₁₀H₂₂) is a component of diesel. Assuming diesel is 100% decane, the complete combustion of decane produces CO₂ and H₂O, and the density of decane is 0.73 g/mL, calculate the mass of CO₂ (in kg) produced if the yearly diesel consumption of the U.S. is 1.78 × 10¹¹ L.

Fireclay is a ceramic usually made by mixing Al(OH)₃, SiO₂, and Mg(OH)₂. The resulting mixture is then heated to 1100 ºC to form Al₂O₃ and MgO by removal of water. The fireclay product has a mass percent composition of 45% Al₂O₃, 50% SiO₂, and 5% MgO. Calculate the amount of each starting material required to create 200 g of fireclay.

Fermentation involves converting glucose (C₆H₁₂O₆) into ethanol (C₂H₅OH) and carbon dioxide. Calculate the mass (in g) and volume (in L) of ethanol produced by the fermentation of 105.3 g of glucose. Assume that at 25 ºC, 1 mole of ethanol has a volume of 58.39 mL.

Ba(OH)₂ or KOH reacts with acids in neutralization reactions. The unbalanced equations are

Ba(OH)₂(aq) + HCl(aq) → BaCl₂(s) + H₂O(l)

KOH(aq) + HCl(aq) → KCl(s) + H₂O(l)

How many kilograms of each item are required to neutralize 1.50 gallons of HCl (1.18 g/mL)?

Pure aluminum can be extracted from the reaction of alumina, Al₂O₃, with carbon: Al₂O₃ + C → Al + CO₂. Balance the chemical equation and calculate the mass of C needed to react with 500 g alumina.

7.00 g of pure Fe metal is produced by the reduction of a 5.18 g sample containing Fe₂O₃ and FeO. How many grams of Fe₂O₃ and FeO are in the original sample?

The structure of leucine, an amino acid, is shown below. A 0.02 mol sample of leucine undergoes combustion analysis. Calculate the moles of CO₂ and H₂O formed.

MX₃ is formed from the reaction between an unidentified metal M and an unidentified halogen X. The compound decomposes when heated and produces MX and X₂.

MX₃(s) → MX (s) + X₂(g)

When 1.18 g of MX₃ is heated, 1.07 g of M and 34.76 mL of X₂ gas are obtained. The volume of 1.00 mol of X₂ under the reaction condition is 22.41 L. Determine the identity of halogen X and its atomic weight.

A sample of vinegar containing acetic acid and water is burned. Vinegar burns and produces water, while the water in the sample just evaporates. The water produced by the combustion of vinegar, as well as the water that evaporates, is collected. The combustion reaction is

CH₃COOH (aq) + O₂ (g) → CO₂ (g) + H₂O (g)

When 5.00 g of the sample is burned, 3.64 g of water is collected. How many grams of acetic acid and water are there in the original sample?

The following equation shows what happens when a compound with the formula XCl₂ meets aqueous AgC₂H₃O₂: 

XCl₂ (aq) + 2 AgC₂H₃O₂ (aq) → X(C₂H₃O₂)₂ (aq) + 2 AgCl (s)

When 1.20 g of XCl₂ in a solution was mixed with too much aqueous AgC₂H₃O₂ in water, 2.53 g of solid AgCl was made. What is the name of the atom X?

CO₂ gas is produced by heating H₂CO₃ at 127 °C. The volume of 1.00 mol of CO₂ is 32.85 L under the same conditions. How much gas in liters is produced when 24.7 g of H₂CO₃ is heated?

The diagram below represents the reaction between ammonia and oxygen to produce nitric oxide and water. Use this diagram to calculate the number of moles of nitric oxide that could be produced from 12 moles of ammonia.

Nitrogen gas (N₂) reacts with magnesium to form magnesium nitride (Mg₃N₂) at 800 °C. The source of nitrogen in this reaction is the atmospheric nitrogen from the air. Air contains about 78% nitrogen, 21% oxygen, and 1% other gases. Since the reaction is exothermic, the released heat can result in the reaction between nitrogen and oxygen to form nitric oxide (NO). If 95% of the nitrogen in the air reacts with magnesium to form magnesium nitride and the remainder reacts with oxygen to form nitric oxide, how many grams of nitric oxide would be produced when 45.0 g of magnesium reacts with excess air?

In the reaction between sodium bicarbonate (NaHCO₃) and acetic acid (CH₃COOH), carbon dioxide gas is evolved:

NaHCO₃(s) + CH₃COOH(aq) → CH₃COONa(aq) + CO₂(g) + H₂O(l)

Calculate the mass of NaHCO₃(s) required to produce 697 in³ of carbon dioxide gas to fill an average-sized balloon. The density of carbon dioxide is 1.78 g/L.

The laboratory preparation of oxygen gas is done by thermal decomposition of potassium chlorate (KClO₃):
2 KClO₃(s) → 2 KCl(s) + 3 O₂(g)
What mass of KClO3 is required to produce 45.00 L of oxygen gas at room temperature? The density of oxygen gas is 1.110 g/L.

A metal from group 2A forms a bromide with the formula MBr₂ and chloride with the formula MCl₂. The bromide can be converted into chloride when reacted with chlorine gas.
MBr₂ + Cl₂ → MCl₂ + Br₂
When a 0.2554 g sample of MBr₂ is reacted with excess Cl₂, 0.1321 g of MCl₂ is produced. What is the atomic weight of the metal M?

Decomposition of nitromethane (CH₃NO₂) takes place according to the following reaction:
2 CH₃NO₂(l) → 2 CO(g) + H₂(g) + N₂(g) + 2 H₂O(g)
How many moles of gases are produced when a 3.125 mL sample of nitromethane is completely decomposed? The density of nitromethane is 1.1371 g/mL.

A reaction that takes place during the extraction of copper metal is the formation of copper metal and CO from Cu₂O and solid carbon. Calculate the mass of Cu₂O required to form 596 kg of copper and the amount of CO produced in the same scenario.

Lighters commonly use butane gas (C₄H₁₀) for fuel. Calculate the mass of carbon dioxide (in g) produced upon the complete combustion of 56.0 mL of butane fluid (approximate contents of a refill bottle). Assume that the density of the fluid is 0.573 g/mL.

The reaction of Fe₂O₃ and CO  produces Fe₃O₄ and CO₂. The Fe₃O₄  can be converted to FeO with its reaction with CO, forming CO₂  as a byproduct. FeO can then react with CO to form Fe and CO₂. If there are 63.5 g of Fe₂O₃ initially, calculate the amount of Fe produced following the series of reactions.

The compound zirconium silicate, ZrSiO₄(s), can be prepared by reacting ZrO₂(s) and SiO₂(s) at high temperatures. Calculate the moles and mass of ZrO₂ needed to produce 3.500 g of ZrSiO₄(s). Assume that the reaction goes to completion.

Lauryl sulfate is an anion found in cleaners and detergents. Its structure is shown below:

Assuming lauryl sulfate decomposes according to the following reaction:

C₁₂H₂₅SO₄^–(aq) + 18 O₂(aq) → 12 CO₂(aq) + 12 H₂O(l) + H⁺(aq) + SO₄^2–(aq)

Calculate the mass of O₂ required to decompose 15.0 g of lauryl sulfate.

An alkaline battery has the following overall reaction:

2 MnO₂(s) + Zn(s) + 2 H₂O(l) → 2 MnO(OH)(s) + Zn(OH)₂(s)

In a certain period of discharge, 131 g of Zn from the anode was converted into Zn(OH)₂(s). Calculate the amount (g) of MnO₂(s) that is reduced at the cathode at the same time.

Calculate the mass of CO₂ (in kg) formed when 2.65 kg of n-hexane is combusted.

H₂ reacts with Cl₂ to produce HCl. Determine the mass of H₂ required to react with 18.9 g of Cl₂ and the mass of HCl produced from it.

A 5.37 g of an alloy containing nickel and copper is placed in HCl liquid. If 6.72 g of CuCl is acquired, determine the mass of nickel and copper in the alloy. Assume all HCl reacts with copper.

For the following unbalanced reaction,

SrS + Co₂(SO₄)₃ → SrSO₄ + Co₂S₃

Determine the mass of Co₂(SO₄)₃ required to completely react with 78.6 g of SrS.

The reaction between zinc and iodine produces zinc iodide. For a mixture of zinc and iodine, 1.2 mol Zn, 3.4 mol I₂ and 2.4 mol ZnI₂ were measured before the reactants were used up. Calculate the initial amount of the reactants.

Magnesium displaces aluminum in aluminum oxide to produce magnesium oxide. 

3 Mg²⁺ + Al₂O₃ → 3 MgO + 2 Al³⁺

If magnesium is added to a solution of 0.50 L aluminum oxide in the form of magnesium nitrate, calculate the mass of magnesium nitrate needed to displace 0.45 M Al³⁺ ions

Determine the mass of HBr that can react with 2.67 g of Sr(OH)₂. 

Sr(OH)₂ + 2 HBr → SrBr₂ + 2 H₂O

Determine the mass of Br₂ produced from the reaction of 7.00 mol of HBr with excess K₂SO₄. 

K₂SO₄ + 2 HBr → K₂SO₃ + Br₂ + H₂O

A 150.0 g mixture of MgCO₃, Mg(ClO₃)₂, and Mg(HCO₃)₂ produces 65.11 g of CO₂, 18.68 g of O₂, and 9.64 g of H₂O.

MgCO₃ (s) → MgO (s) + CO₂ (g)

Mg(ClO₃)₂ (s) → MgCl₂ (s) + 3 O₂ (g)

Mg(HCO₃)₂ (s) → MgO (s) + 2 CO₂ (g) + H₂O (g)

Determine the composition of the mixture.

Methane, ethane, and propane are burnt in excess oxygen in three separate reaction vessels. The mass burnt for each fuel was 3.45 g. Determine which fuel will generate the largest amount of CO₂?

If 5.7 moles of N₂O₅ react, how many moles of NO₂ form?

N₂O₅( g) → NO₂( g) + O₂(g)

You want to dissolve an aluminum rod weighing 1.5 kg. What is the minimum mass of H₂SO₄ (in g) required to react with aluminum? How much (in g) H₂ gas is produced if the aluminum rod reacts completely?

Al(s) + H₂SO₄(aq) → Al₂(SO₄)₃(aq) + H₂(g)

A petroleum sample is composed of 23.29% heptane (C₇H₁₆), 52.18% hexane (C₆H₁₄), and the rest octane (C₈H₁₈). If 38 kg of this sample is combusted completely, calculate the maximum mass of carbon dioxide formed.

According to the following chemical equation, how many grams of HBr are needed to completely dissolve 1.3 kg pure iron?

Fe(s) + HBr(aq) → FeBr₂(aq) + H₂(g).

Calculate grams of product that form when 23.59 g of O₂ completely reacts. Assume other reactant is in excess.

2 Sr(s) + O₂(g) → 2 SrO(s)

Determine the mass (in grams) of Ca(OH)₂ required to completely neutralize 3.41 g of HC₂H₃O₂.

HC₂H₃O₂(aq) + Ca(OH)₂(aq) → H₂O(l) + Ca(C₂H₃O₂)₂(aq)

Note: make sure to balance the equation.

Calculate the mass of oxygen consumed in the combustion of 2.21 g of C₃H₈

Write the balanced reaction for the reaction of aluminum sulfide with water producing aluminum hydroxide and hydrogen sulfide.

If 10.5 g of aluminum sulfide was allowed to react calculate the mass of aluminum hydroxide produced. 

Potassium superoxide, KO₂, is used to convert carbon dioxide and water into oxygen

4 KO₂ (s) + 4 CO₂ (g) + 2 H₂O (g) → 4 KHCO₃ (s) + 3 O₂ (g)

Calculate the number of molecules of O₂ (g) produced from the 0.0692 g CO₂ (g)

Barium chloride and water are produced by the reaction of hydrochloric acid and barium hydroxide:

2HCl (aq) + Ba(OH)₂ (aq) → BaCl₂ (aq) +2H₂O (l) 

Consider 6 moles of barium hydroxide that reacted. 

Calculate the amount of the products made and the amount of the other reactant consumed

____ moles of hydrochloric acid is consumed.

____ moles of barium chloride and ____ moles of water are produced.

The balanced reactions below shows the combustion of propane:

C₃H₈ (g) + 5 O₂ (g) → 3 CO₂ (g) + 4 H₂O (g) 

If 132.1 g of C₃H₈(g) is completely combusted, calculate the mass in grams of oxygen needed for this process.

The combustion of octane is represented by the balanced reaction below: 

2 C₈H₁₈ + 2 5O₂ → 16 CO₂ + 18 H₂O 

If 39.27 g of C₈H₁₈ is combusted, calculate the moles of CO₂ produced

Assume that you are performing a stoichiometric calculation wherein you want to calculate the mass of the product from a given mass of reactant. After writing the balanced chemical equation and determining the mole ratio, what is the next step in the mass calculation for the reaction?

True or False: The balanced chemical equation Na₃PO₄(aq) + CaCl₂(aq) → Ca₃(PO₄)₂(s) + NaCl(aq) can be used to determine the stoichiometry of the reaction, and the mole ratio of Na₃PO₄ to NaCl is 1:1.

Which of the following must be done in order to use the mole ratio in stoichiometry problems?

Which of the following is required in each of all types of reaction stoichiometry calculations?

What is the typical initial procedure for determining the stoichiometry of a reaction?

What is the fundamental principle that stoichiometry is based on?

Give the general procedure for determining the required quantity of reactant A to produce a certain mass of product B in a hypothetical chemical reaction.

Solid potassium chlorate (KClO₃) decomposes into solid potassium chloride (KCl) and oxygen gas (O₂). Assuming that you start with 5.00 g of KClO₃, how do you calculate the grams of KCl produced? Show the step-by-step calculation.

Which of these statements provides the best explanation for the importance of mole ratios in stoichiometric calculations?

Choose the statement that best defines stoichiometry.

Which of the following refers to the relationship between the amounts of substances involved in a balanced chemical reaction?

Which of the following can be used to determine the amount of the reactants and products in a reaction?

Olive oil (C₈₈H₁₆₄O₁₀) is an oil extracted from the olive plant. What is the mass of H₂O produced in the metabolism of 1.00 kg of olive oil? Assume that C₈₈H₁₆₄O₁₀ only reacts with O₂ to produce CO₂ and H₂O. 

A hypothetical method uses the following equation to determine the amount of SO₂ in the gas by passing a sample through a sodium carbonate-containing vessel which removes the SO₂. 

Na₂CO₃(aq) + H₂O(l) + 2 SO₂(g) → 2 NaHSO₃(aq) + CO₂(g)

How much Na₂CO₃ in moles is required for the removal of 6.29×10⁻⁶ mol of SO₂?

Propane (C₃H₈) is a component of liquefied petroleum gas (LPG). It burns completely as follows: C₃H₈(g) + 5 O₂(g) → 3 CO₂(g) + 4 H₂O(g)
How many grams of O₂ are needed to be able to burn 13.5 gal of C₃H₈ if the density of propane at 25.0 °C is 0.493 g/mL?

Soda lime (Ca(OH)₂) and nitrogen dioxide (NO₂) can react according to the following reaction:
4 NO₂(g) + 2 Ca(OH)₂(s) → Ca(NO₃)₂(aq) + 2 H₂O(l) + Ca(NO₂)₂(aq)
This demonstrates how Ca(OH)₂ can be used to absorb NO₂ gas. How many moles of NO₂ can be absorbed when 0.367 mol Ca(OH)₂ reacts in this manner?

Soda lime (Ca(OH)₂) and nitrogen dioxide (NO₂) can react according to the following reaction: 

4 NO₂(g) + 2 Ca(OH)₂(s) → Ca(NO₃)₂(aq) + 2 H₂O(l) + Ca(NO₂)₂(aq)

This demonstrates how Ca(OH)₂ can be used to absorb NO₂ gas. How many grams of Ca(OH)₂ are required to absorb 5.29 g of NO₂?

Propane (C₃H₈) is a component of liquefied petroleum gas (LPG). It burns completely as follows: C₃H₈(g) + 5 O₂(g) → 3 CO₂(g) + 4 H₂O(g)

How many moles of O₂ must be burned to produce 6.67 moles of C₃H₈?

Calculate the moles of PCl₃ formed when 87.2 g of P₄ reacts with excess Cl₂. Reaction: P₄(s) + 6 Cl₂(g) → 4 PCl₃(l)

The process of CAD welding involves copper (II) oxide and aluminum reacting: 3 CuO(s) + 2 Al(s) → 3 Cu(s) + Al₂O₃. Calculate the mass of Al needed to react with 6.4 g of CuO and the mass of Cu formed, assuming the reaction goes to completion.

For the reaction 2 A + B → 3 C + 2 D, fill the table below with the missing values. If a value for a reactant is given, provide the correct values for both products and the other reactant. If a value for a product is given, provide the correct values for both reactants and the other product.

For this reaction, calculate the mass (in grams) of the product that forms when 15.39 g of the underlined reactant completely reacts. Assume that there is more than enough of the other reactant.

2 Sr(s) + O₂(g) → 2 SrO(s)

An important reaction that takes place in a blast furnace during the production of iron is the formation of iron metal and CO₂ from Fe₂O₃ and CO. Determine the mass of Fe₂O₃ required to form 910 kg of iron. Determine the amount of CO₂ that forms in this process.

The complete combustion of octane, C₈H₁₈, a component of gasoline, proceeds as follows: 2 C₈H₁₈(l) + 25 O₂(g) → 16 CO₂(g) + 18 H₂O(g) (c) Octane has a density of 0.692 g/mL at 20°C. How many grams of O₂ are required to burn 22.0 gal of C₈H₁₈?

The combustion of gasoline produces carbon dioxide and water. Assume gasoline to be pure pentane (C₅H₁₂) and calculate the mass (in kg) of carbon dioxide that is added to the atmosphere per 1.0 kg of pentane burned. (Hint: Begin by writing a balanced equation for the combustion reaction.)

A liquid fuel mixture contains 31.25% pentane (C₅H₁₂), 17.43% hexane (C₆H₁₄), and the rest nonane (C₉H₂₀). What is the maximum mass of carbon dioxide produced by the complete combustion of 10.0 kg of this fuel mixture?

Hydrofluoric acid, HF(aq), cannot be stored in glass bottles because compounds called silicates in the glass are attacked by the HF(aq). Sodium silicate Na₂SiO₃, for example, reacts as follows: Na₂SiO₃(s) + 8 HF(aq) → H₂SiF₆(aq) + 2 NaF(aq) + 3 H₂O(l)

How many grams of NaF form when 0.630 mol of HF reacts with excess Na₂SiO₃?

Magnesium sulfide reacts with water to form magnesium hydroxide and hydrogen sulfide.

(a) Write the balanced chemical equation for this reaction.

(b) How many grams of magnesium hydroxide are obtained from 11.5 g of magnesium sulfide?