3. Chemical Reactions

Balancing a chemical equation

When the following equation is balanced, what is the coefficient in front of H₂O?

___ Ba(OH)₂ + ___ H₃PO₄ → ___ H₂O + ___ Ba₃(PO₄)₂

In the following equation what is the mole ratio of NaOH to H₂O, respectively?

___NaOH (aq) + ___ H₃PO₄(aq) → ___ H₂O(l) + ___ Na₃PO₄(aq)

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

The reaction between reactant A (blue spheres) and reactant B (red spheres) is shown in the following diagram:

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

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

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.

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.

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.

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

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

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

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

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

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

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

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

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

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.

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.

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.

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.

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

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

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

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

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

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.

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.

Which of the following equations is balanced? (a) The development reaction in silver-halide photography: 2 AgBr + 2 NaOH + C6H6O2¡2 Ag + H2O + 2 NaBr + C6H4O2 (b) The preparation of household bleach: 2 NaOH + Cl2¡NaOCl + NaCl + H2O

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) UO2 + HF --> UF4 + H2O

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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

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

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.

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.

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.

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.

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.

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

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

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

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.

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.

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

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

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

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

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.

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

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.

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

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.)

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.)

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

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.

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.

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

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

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

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

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.

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

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

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.

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

(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.

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)

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.

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.

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.

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.

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.

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.

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.

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.

Solid iron(iii) oxide reacts with hydrogen gas to form solid iron and liquid water.

When iron rusts, solid iron reacts with gaseous oxygen to form solid iron(iii) oxide.

Write the balanced chemical equation for the reaction shown.

When the following equation is balanced the coefficients are

Liquid octane reacts with oxygen gas to form carbon dioxide gas and water vapor.

Gaseous carbon monoxide reacts with hydrogen gas to form gaseous methane (ch4) and liquid water.

Solid aluminum sulfide reacts with water to form solid aluminum hydroxide and gaseous hydrogen sulfide.

How many moles of o2 are in the chemical equation when balanced using the lowest whole numbers?

Write the balanced chemical equation for the reaction, using lowest whole-number coefficients.

The scientific principle which is the basis for balancing chemical equations is

Which sequence of coefficients should be placed in the blanks to balance this equation?

Add coefficients to the following reaction summary