3. Chemical Reactions

Balancing Chemical Equations

How To Balance Chemical Equations

When 10.0 g of a mixture of Ca1ClO322 and 
Ca1ClO22 is heated to 700 °C in a 10.0-L vessel, both compounds 
decompose, forming O21g2 and CaCl21s2. The final 
pressure inside the vessel is 1.00 atm. 
(a) Write balanced equations for the decomposition reactions.

Chemical explosions are characterized by the instantaneous 
release of large quantities of hot gases, which set up a shock 
wave of enormous pressure (up to 700,000 atm) and velocity 
(up to 20,000 mi/h). For example, explosion of nitroglycerin 
1C3H5N3O92 releases four gases, A, B, C, and D: 
n C3H5N3O91l2¡a A1g2 + b B1g2 + c C1g2 + d D1g2 
Assume that the explosion of 1 mol (227 g) of nitroglycerin 
releases gases with a temperature of 1950 °C and a 
volume of 1323 L at 1.00 atm pressure. 
(e) Write a balanced equation for the explosion of 
nitroglycerin.

Write balanced chemical equations to correspond to each
of the following descriptions:
(b) Boron sulfide, B2S31s2, reacts violently with water to
form dissolved boric acid, H3BO3, and hydrogen sulfide
gas.

A 1.50-g sample of quinone 1C6H4O22 is burned in a bomb
calorimeter whose total heat capacity is 8.500 kJ>°C. The temperature
of the calorimeter increases from 25.00 to 29.49°C.
(a) Write a balanced chemical equation for the bomb calorimeter
reaction.

Acid spills are often neutralized with sodium carbonate or sodium hydrogen carbonate. For neutralization of acetic acid, the unbalanced equations are
112 CH3CO2H1l2 + Na2CO31s2 S
CH3CO2Na1aq2 + CO21g2 + H2O1l2 122 CH3CO2H1l2 + NaHCO31s2
CH3CO2Na1aq2 + CO21g2 + H2O1l2
(a) Balance both equations.

The following diagram shows the combination reaction
between hydrogen, H2, and carbon monoxide, CO, to
produce methanol, CH3OH (white spheres are H, black spheres
are C, red spheres are O). The correct number of CO molecules
involved in this reaction is not shown.
(b) Write a balanced chemical equation for the reaction.

Balance the following equations. 
(c) S + O2 --> SO3

Write the balanced chemical equation for the reaction of
aqueous potassium hydroxide with aqueous iron(III) chloride
to form solid iron(III) hydroxide and aqueous potassium
chloride.

Write the balanced chemical equation for each reaction.
a. Solid copper reacts with solid sulfur to form solid copper(I)
sulfide.

Balance each chemical equation.
b. Co(NO3)3(aq) + (NH4)2S(aq)¡Co2S3(s) + NH4NO3(aq)

The following pictures represent equilibrium mixtures at 325 K and 350 K for a reaction involving A atoms (red), B atoms (blue), and AB molecules.  (a) Write a balanced equation for the reaction that occurs on raising the temperature.

Balance the following equations. 
(a) C6H5NO2 + O2 --> CO2 + H2O + NO2

Complete and balance each hydrocarbon combustion reaction.
c. CH‚CCH2CH3 + O2 ¡

Balance the following equations: 
(c) Ba3N21s2 + H2O1aq2¡Ba(OH)21aq2 + NH31g2

Calcium hydride reacts with water to form calcium hydroxide
and hydrogen gas. (a) Write a balanced chemical
equation for the reaction.

Write the balanced chemical equation for each reaction.
b. Solid iron(III) oxide reacts with hydrogen gas to form solid
iron and liquid water.

Complete and balance each hydrocarbon combustion reaction. 
b.CH3CH2CH“CH2 +O2 ¡

How to Balance a Chemical Equation EASY

The ionic substance strontium oxide, SrO, forms from the
reaction of strontium metal with molecular oxygen. The arrangement
of the ions in solid SrO is analogous to that in solid
NaCl:

(a) Write a balanced equation for the formation of SrO(s)
from its elements.

Balance the following equations. 
(d) UO2 + HF --> UF4 + H2O

When iron rusts, solid iron reacts with gaseous oxygen to form
solid iron(III) oxide. Write the balanced chemical equation for
this reaction.

Balance the following equations:
(c) MnO21s2 + HCl1aq2 ¡MnCl21s2 + H2O1l2 + Cl2(g)

Consider the mixture of propane, C3H8, and O2 shown here.
(a) Write a balanced equation for the combustion reaction that
occurs between propane and oxygen.

Balance the following equations. 
(a) SiCl4 + H2O --> SiO2 + HCl

The fluoride ion reacts with water to produce HF. (a) Write out the chemical equation for this reaction.

Write the balanced chemical equation for each reaction.
d. Gaseous ammonia (NH3) reacts with gaseous oxygen to form
gaseous nitrogen monoxide and gaseous water.

A key step in balancing chemical equations is correctly identifying
the formulas of the reactants and products. For example,
consider the reaction between calcium oxide, CaO(s),
and H2O1l2 to form aqueous calcium hydroxide.
(b) Is it possible to balance the equation if you incorrectly
identify the product as CaOH1aq2, and if so, what is the
equation?

Balance the following equations: 
(b) Au2S31s2 + H21g2¡Au1s2 + H2S1g2

Nitrogen 1N22 and hydrogen 1H22 react to form ammonia
1NH32. Consider the mixture of N2 and H2 shown in the
accompanying diagram. The blue spheres represent N, and
the white ones represent H. (a) Write the balanced chemical
equation for the reaction.

Balancing Chemical Equations Step by Step Practice Problems | How to Pass Chemistry

Write a balanced chemical equation for the reaction that 
occurs when (c) the hydrocarbon styrene, C8H81l2, is combusted 
in air

The reaction of A2 (red spheres) with B2 (blue spheres) is shown in the diagram. What is the balanced chemical equa-tion? (LO 3.1) 
(a) 2 A2 + 6 B2 ---> 4 AB3 
(b) 4 A + 12 B ---> 4 AB3 
(c) 4 A + 12 B ---> A4 + B12 
(d) A2 + 3 B2 ---> 2 AB3

One of the most bizarre reactions in chemistry is called the
Ugi reaction:
R1C(=O)R2 + R3 - NH2 + R4COOH + R5NC S
R4C(=O)N(R3)C(R1R2)C=ONHR5 + H2O
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/952005672433e6c8-1660321922561.jpg" alt="" />
(a) Write out the balanced chemical equation for the Ugi reaction,
for the case where R = CH3CH2CH2CH2CH2CH2—
(this is called the hexyl group) for all compounds.

Chlorine reacts with oxygen to form Cl2O7. (b) Write a balanced 
equation for the formation of Cl2O71l2 from the elements.

Balance the following equations. 
(b) The spoilage of wine into vinegar: C2H6O + O2 --> C2H4O2 + H2O

How to Balance Chemical Equations in 5 Easy Steps: Balancing Equations Tutorial

Balance the following equations. 
(b) P4O10 + H2O --> H3PO4

Write the balanced chemical equation for the fermentation of
sucrose (C12H22O11) by yeasts in which the aqueous sugar reacts
with water to form aqueous ethanol (C2H5OH) and carbon dioxide
gas.

The equation is not balanced.  There should be 12 H atoms and 16 O atoms on each side of the equation.

The formulas for reactants and products are correct and the equation can be balanced.

 Chemical reactions are represented by chemical equations that must obey the law of conservation of mass; the number of atoms of each type must be the same on both sides of the equation. 

When the following equation is balanced, what is the coefficient in front of H2O?___ Ba(OH)2 + ___ H3PO4 &#8594; ___ H2O + ___ Ba3(PO4)2

Write “true” or “false” for each statement. (a) We balance
chemical equations as we do because energy must be conserved.

The reaction of tungsten hexachloride (WCl6) with bismuth gives hexatungsten dodecachloride (W6Cl12). WCl6 + Bi ---> W6Cl12 + BiCl3 Unbalanced
(a) Balance the equation.

Balance the following equations. 
(a) Mg + HNO3 --> H2 + Mg(NO3)2

The following reaction is exothermic:
(a) Write a balanced equation for the reaction (red spheres represent A atoms and ivory spheres represent B atoms)

Nitric acid is a component of acid rain that forms when gaseous
nitrogen dioxide pollutant reacts with gaseous oxygen and liquid
water to form aqueous nitric acid. Write the balanced chemical
equation for this reaction. (Note: this is a simplified
representation of this reaction.)

is necessary to observe the law of conservation of energy.

Balancing insure not violation of the law of conservation of mass.

involves adding coefficients and changing subscripts.

The subscripts in the chemical formulas are never changed in balancing an equation.

ensures that the same number of molecules are present in the reactants and products.

The number of molecules may or may not be the same in a reaction, this depends on the exact reaction involved.

results in the same number of atoms of each element are present in reactants and product.

Correct, this provides consistency with the law of conservation of mass.

 Consider that the term balancing implies a type of equality between the reactants and products. 

Element M is prepared industrially by a two-step procedure according to the following (unbalanced) equations: 
Assume that 0.855 g of M2O3 is submitted to the reaction sequence. When the HCl produced in step (2) is dissolved in water and titrated with 0.511 M NaOH, 144.2 mL of the NaOH solution is required to neutralize the HCl. 
(a) Balance both equations.

Sulfuric acid is a component of acid rain formed when gaseous
sulfur dioxide pollutant reacts with gaseous oxygen and liquid
water to form aqueous sulfuric acid. Write the balanced chemical
equation this reaction. (Note: this is a simplified representation
of this reaction.)

Balance the following equations: 
(d) KOH1aq2 + H3PO41aq2 ¡K3PO41aq2 + H2O1l2

Balance the following equations. 
(c) The burning of rocket fuel: C2H8N2 + N2O4 --> N2 + CO2 + H2O

Balance the following equations:
(b) NH31g2 + O21g2¡NO1g2 + H2O1g2

Balance the following equations. 
(b) Au + H2SeO4 --> Au2(SeO4)3 + H2SeO3 + H2O

Write balanced chemical equations corresponding to each of 
the following descriptions: 
(c) When hydrogen 
gas is passed over solid hot iron(III) oxide, the resulting 
reaction produces iron and gaseous water.

Balancing Chemical Equations Part 1 | Don't Memorise

Determine the total sum of the coefficients after balancing the following equation. &nbsp;<img src="https://cdn.clutchprep.com/problem_images/147361-d1e2f27ed8cce1fb.png"alt=""/>

Write balanced chemical equations to correspond to each
of the following descriptions:
(c) Phosphine, PH31g2, combusts in oxygen gas to
form water vapor and solid tetraphosphorus decaoxide.

Sulfur tetrafluoride 1SF42 reacts slowly with O2 to form sulfur 
tetrafluoride monoxide 1OSF42 according to the following 
unbalanced reaction: 
SF41g2 + O21g2¡OSF41g2 
The O atom and the four F atoms in OSF4 are bonded to a 
central S atom. (a) Balance the equation.

When solid mercury(I) carbonate, Hg2CO3, is added to
nitric acid, HNO3, a reaction occurs to give mercury(II)
nitrate, Hg1NO322, water, and two gases A and B:
Hg2CO31s2 + HNO31aq2¡
Hg1NO3221aq2 + H2O1l 2 + A1g2 + B1g2
(e) Write a balanced equation for the reaction of mercury(I)
carbonate with nitric acid.

Balancing Chemical Equations Example 1

When a gaseous compound X containing only C, H, and O is burned in O2, 1 volume of the unknown gas reacts with 3 volumes of O2 to give 2 volumes of CO2 and 3 volumes of gaseous H2O. Assume all volumes are measured at the same temperature and pressure.
(a) Calculate a formula for the unknown gas, and write a
balanced equation for the combustion reaction.

(c) What is the sum of the coefficients in the balanced
chemical equation for the combustion of one mole of
acetone, C3H6O1l2, in air?

Balance the following equations: 
(d) Na2CO31aq2 + HCl1aq2¡NaCl1aq2 + H2O1l2 + CO2(g)

Write balanced complete ionic and net ionic equations for each 
reaction. 
b. MgS(aq) + CuCl2(aq)¡CuS(s) + MgCl2(aq)

Balance the following equations. 
(a) VCl3 + Na + CO --> V(CO)6 + NaCl

The diagrams represent a reaction on the molecular level. Atoms of A are represented with red spheres, and atoms of B are represented with blue spheres. Write a balanced chemical equation.

Predict the products and write a balanced molecular equation
for each reaction. If no reaction occurs, write “NO REACTION.”
c. liquid pentanol (C5H12O) and gaseous oxygen

Balance the following equations: 
(b) Cu1s2 + HNO31aq2¡Cu(NO3)21aq2 + NO21g) + H2O(l)

Balance the following equations. 
(c) CaCN2 + H2O --> CaCO3 + NH3

The reaction between reactant A (blue spheres) and reactant
B (red spheres) is shown in the following diagram:
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/fb91fcec1a1ddac6-1660320606440.jpg" alt="" />
Based on this diagram, which equation best describes the
reaction? 
(a) A2 + B¡A2B
(b) A2 + 4 B¡2 AB2
(c) 2 A + B4¡2 AB2
(d) A + B2¡AB2

At 900 °C, titanium tetrachloride vapor reacts with molten
magnesium metal to form solid titanium metal and molten magnesium chloride. 
(a) Write a balanced equation for
this reaction.

Isooctane, C8H18, is the component of gasoline from which
the term octane rating derives.
(a) Write a balanced equation for the combustion of isooctane
to yield CO2 and H2O.

A 2.20-g sample of phenol 1C6H5OH2 was burned in a bomb
calorimeter whose total heat capacity is 11.90 kJ>°C. The
temperature of the calorimeter plus contents increased from
21.50 to 27.50 °C. (a) Write a balanced chemical equation for
the bomb calorimeter reaction.

The following diagram shows the combination reaction
between hydrogen, H2, and carbon monoxide, CO, to
produce methanol, CH3OH (white spheres are H, black spheres
are C, red spheres are O). The correct number of CO molecules
involved in this reaction is not shown.
(a) Determine the number of CO molecules that should be
shown in the left (reactants) box.
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/a17d1099893ef4b4-1664220022260.jpg" alt="" />

Write the balanced equation for the following by inserting the correct coefficients in the blanks. &nbsp;<img src="https://cdn.clutchprep.com/problem_images/147358-016b6a67b40710b4.png"alt=""/>

Balance the following equations. 
(b) Ca3(PO4)2(s) + SiO2(s) + C(s) --> P4(g) + CaSiO3(l) + CO(g)

During photosynthesis, plants use energy from sunlight to form
glucose (C6H12O6) and oxygen from carbon dioxide and water.
Write a balanced equation for photosynthesis.

Magnesium metal burns in oxygen to form magnesium oxide, MgO. 
(a) Write a balanced equation for the reaction.

Write the balanced chemical equation for the reaction of solid
lithium with liquid water.

Which of the following equations is balanced? Balance any that need it.
(a) The thermite reaction, used in welding: Al + Fe2O3 --> Al2O3 + Fe

Balance the following equations. 
(d) NO2 + H2O --> HNO3 + NO

The following reaction of A3 molecules is spontaneous.  (a) Write a balanced equation for the reaction.

The following pictures represent the initial and equilibrium states for the exothermic decomposition of gaseous A mol- ecules (red) to give gaseous B molecules (blue). (a) Write a balanced chemical equation for the reaction.

Balance the following equations: 
(c) Al(OH)31s2 + H2SO41l2¡Al2(SO4)3(s) + H2O(l)

Write balanced chemical equations for (a) the complete 
combustion of acetone (CH3COCH3), a common organic 
solvent

What are the coefficients in the balanced equation for the combustion of ethanol? (LO 3.2) 
(a) 1, 3, 2, 3
(b) 2, 3, 4, 3
(c) 2, 7, 4, 6
(d) 1, 4, 2, 3

Balance the following equations. 
(b) CaC2 + H2O --> Ca(OH)2 + C2H2

Balancing Chemical Equations Practice Problems

Write the balanced chemical equation for each reaction.
c. Aqueous hydrochloric acid reacts with solid manganese(IV)
oxide to form aqueous manganese(II) chloride, liquid water,
and chlorine gas.

The following pictures represent the initial and equilibrium states for the exothermic reaction of solid A (red) with gas- eous B2 (blue) to give gaseous AB.  (a) Write a balanced chemical equation for the reaction.

Balance the following equations. 
(a) CO(NH2)2(aq) + HOCl(aq) --> NCl3(aq) + CO2(aq) + H2O(l)

Diethyl ether, C4H10O1l2, a flammable compound that was
once used as a surgical anesthetic, has the structure

The complete combustion of 1 mol of C4H10O1l2 to CO21g2
and H2O1l2 yields H° = -2723.7 kJ. (a) Write a balanced
equation for the combustion of 1 mol of C4H10O1l2.

Combustion analysis of 0.1500 g of methyl tert-butyl ether, an octane booster used in gasoline, gave 0.3744 g of CO2 and 0.1838 g of H2O. When a flask having a volume of 1.00 L was evacuated and then filled with methyl tertbutyl ether vapor at a pressure of 100.0 kPa and a temperature of 54.8 °C, the mass of the flask increased by 3.233 g.

(c) Write a balanced equation for the combustion reaction.

The following pictures represent the initial state and the equilibrium state for the reaction of A2 molecules (red) with B atoms (blue) to give AB molecules.  (a) Write a balanced chemical equation for the reaction.

Write a balanced chemical equation for the reaction that 
occurs when (b) barium carbonate 
decomposes into barium oxide and carbon dioxide gas 
when heated

Isooctane, C8H18, is the component of gasoline from which the term octane rating derives. (a) Write a balanced equation for the combustion of isooctane(l) with O2 to yield CO2(g) and H2O(l)

Write the balanced chemical equation for each reaction.
d. Liquid pentane (C5H12) reacts with gaseous oxygen to form
carbon dioxide and liquid water.

Balance the following equations. 
(a) The explosion of ammonium nitrate: NH4NO3 --> N2 + O2 + H2O

Write balanced chemical equations to correspond to each
of the following descriptions:
(d) When solid mercury(II) nitrate is heated, it decomposes
to form solid mercury(II) oxide, gaseous nitrogen
dioxide, and oxygen.

Balance the following equations. 
(c) NH4ClO4 + Al --> Al2O3 + N2 + Cl2 + H2O

Write the balanced chemical equation for each reaction.
a. Solid lead(II) sulfide reacts with aqueous hydrobromic
acid to form solid lead(II) bromide and dihydrogen monosulfide
gas.

Write a balanced chemical equation for the reaction that
occurs when (d) dimethylether, CH3OCH31g2, is combusted
in air.

Write a balanced equation for the synthesis of the 2–6 semiconductor 
ZnTe by chemical vapor deposition from dimethylzinc, 
Zn1CH322, and diethyltellurium, Te1CH2CH322, assuming that 
the other product is gaseous propane 1CH3CH2CH32.

Write the balanced chemical equation for each reaction.
b. Gaseous carbon monoxide reacts with hydrogen gas to form 
gaseous methane (CH4) and liquid water.

Write a balanced chemical equation for the reaction that occurs 
when (b) silver(I) 
oxide decomposes into silver metal and oxygen gas when 
heated

Check that you have correctly balanced the equation. This is not the ratio of NaOH to H2O in the balanced equation.

Correct, 3 mol of NaOH produces 3 mol H2O in the reaction.

 Begin by balancing the equation, then use the coefficients to determine the ratio. 

In the following equation what is the mole ratio of NaOH to H2O, respectively? ___NaOH (aq) + ___ H3PO4(aq) &#8594; ___ H2O(l) + ___ Na3PO4(aq)

Write the balanced chemical equation for the reaction that occurs when the gasoline additive methyl tert-butyl ether, C5H12O (l), burns in air.

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Professor Dave Explains

1. Intro to General Chemistry

2. Atoms & Elements

4. BONUS: Lab Techniques and Procedures

5. BONUS: Mathematical Operations and Functions

6. Chemical Quantities & Aqueous Reactions

7. Gases

8. Thermochemistry

9. Quantum Mechanics

10. Periodic Properties of the Elements

11. Bonding & Molecular Structure

12. Molecular Shapes & Valence Bond Theory

13. Liquids, Solids & Intermolecular Forces

14. Solutions

15. Chemical Kinetics

16. Chemical Equilibrium

17. Acid and Base Equilibrium

18. Aqueous Equilibrium

19. Chemical Thermodynamics

20. Electrochemistry

21. Nuclear Chemistry

22. Organic Chemistry

23. Chemistry of the Nonmetals

24. Transition Metals and Coordination Compounds

[BOOK CHEM] Clutch Version

Empirical Formula

The empirical formula gives the relative number of atoms.&nbsp;

Percent Yield

The Percent Yield determines how successful the product yield is in a chemical reaction.&nbsp;

Molecular Formula

The&nbsp;molecular formula gives the actual number of atoms.

Naming Ionic Compounds

An ionic compound is composed of a positive ion and a negative ion.&nbsp;

Functional Groups in Chemistry

The Functional Group is the portion of a molecule that is responsible for its chemical reactivity.&nbsp;

Naming Molecular Compounds

Molecular Compounds, also known as covalent compounds, contain only non-metals bonded together.&nbsp;

Naming Ionic Hydrates

An Ionic Hydrate is an ionic compound that is linked to at least one molecule of H2O.&nbsp;

Stoichiometry

Stoichiometry deals with the numerical relationship between compounds in a balanced chemical equation.

Writing Ionic Compounds

Determining the charges of a cation and anion are fundamental in Writing Ionic Compounds.

Polyatomic Ions

Polyatomic Ions are groups of multiple elements that possess a charge.

Balancing Chemical Equations is the first step in future chemical calculations.

Limiting Reagent

The Limiting Reagent represents the compound that is totally consumed in the reaction.&nbsp;

Combustion Analysis

Under Combustion Analysis, the empirical formula of a compound is determined through a combustion reaction.&nbsp;

Mass Percent

Mass Percent is the percentage of a particular element within a compound.&nbsp;

Combustion Apparatus

A Combustion Apparatus vaporizes a sample into gases to later determine its formula.

Naming Acids

Acids, for the most part, are covalent compounds that begin with a hydrogen.&nbsp;