For the reaction 3O2( g) ⇌ 2O3( g) The equilibrium constant, K, has the value 1.12 * 10-54 at a particular temperature. a. What does the very small equilibrium constant indicate about the extent to which oxygen gas, O2( g), is converted to ozone gas, O3( g), at this temperature? b. If the equilibrium mixture is analyzed and [O2( g)] is found to be 3.04 * 10-2 M, what is the concentration of O3( g) in the mixture?
> Consider the iron alloy described in Question 19. Suppose it is desired to prepare 1.00 kg of this alloy. What mass of each component would be necessary? From 19: A sample of an iron alloy contains 92.1 g Fe, 2.59 g C, and 1.59 g Cr. Calculate the perce
> A sample of an iron alloy contains 92.1 g Fe, 2.59 g C, and 1.59 g Cr. Calculate the percent by mass of each component present in the alloy sample.
> In each of the following chemical equations, identify the conjugate acid–base pairs. a. NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq) b. PO43-(aq) + H2O(l) ⇌ HPO42-(aq) + OH-(aq) c. C2H3O2-(aq) + H2O(l) ⇌ HC2H3O2(aq) + OH-(aq)
> Calculate the mass, in grams, of solute present in each of the following solutions. a. 375 g of 1.51% ammonium chloride solution b. 125 g of 2.91% sodium chloride solution c. 1.31 kg of 4.92% potassium nitrate solution d. 478 mg of 12.5% ammonium nit
> A solution that is 9% by mass glucose contains 9 g of glucose in every g of solution.
> How do we define the mass percent composition of a solution? Give an example of a solution, and explain the relative amounts of solute and solvent present in the solution in terms of the mass percent composition.
> Which of the following acids have relatively strong conjugate bases? a. HCN b. H2S c. HBrO4 d. HNO3
> The label “concentrated H2SO4” on a bottle means that there is a relatively amount of H2SO4 present in the solution.
> A solution is a homogeneous mixture and, unlike a compound, has composition.
> If additional solute is added to a(n) solution, it will dissolve.
> What does it mean to say that a solution is saturated with a solute?
> Which of the following do not represent a conjugate acid–base pair? For those pairs that are not conjugate acid–base pairs, write the correct conjugate acid–base pair for each species in the pair. a. H2SO4, SO42- b. H2PO4-, HPO42- c. HClO4, Cl- d. NH
> Which of the following do not represent a conjugate acid–base pair? For those pairs that are not conjugate acid–base pairs, write the correct conjugate acid–base pair for each species in the pair. a. HI, I- b. HClO, HClO c. H3PO4, PO43- d. H2CO3, CO3
> In a solution, the substance present in the largest amount is called the , whereas the other substances present are called the .
> Suppose you dissolved a teaspoon of sugar in a glass of water. Which substance is the solvent? Which substance is the solute?
> Gaseous phosphorus pentachloride decomposes according to the reaction PCl5(g) ⇌ PCl3(g) + Cl2(g) The equilibrium system was analyzed at a particular temperature, and the concentrations of the substances present were determined to be [PCl5] = 1.1 * 10-2
> For the reaction N2(g) + 3Cl2(g) ⇌ 2NCl3(g) an analysis of an equilibrium mixture at a particular temperature is performed. It is found that [NCl3] = 1.9 * 10-1 M, [N2] * 1.4 * 10-3 M, and [Cl2] = 4.3 * 10-4 M. Calculate K for the reaction.
> True or false? The position of a heterogeneous equilibrium does not depend on the amounts of pure solid or pure liquid reactants or products present because the concentrations of pure solids and liquids cannot change.
> Write the equilibrium expression for each of the following reactions. a. 2O3( g) ⇌ 3O2( g) b. CH4( g) + 2O2( g) ⇌ CO2( g) + 2H2O( g) c. C2H4( g) + Cl2( g) ⇌ C2H4Cl2( g)
> Write the equilibrium expression for each of the following reactions. a. H2( g) + Br2( g) ⇌ 2HBr( g) b. 2H2( g) + S2( g) ⇌ 2H2S( g) c. H2( g) + C2N2( g) ⇌ 2HCN( g)
> How does an increase in temperature result in an increase in the number of successful collisions between reactant molecules? What does an increase in temperature mean on a molecular basis?
> How does the collision model account for the fact that a reaction proceeds faster when the concentrations of the reactants are increased?
> When writing a chemical equation for a reaction that comes to equilibrium, how do we indicate symbolically that the reaction is reversible?
> For the reaction CaCO3(s) ⇌ CaO(s) + CO2(g) the equilibrium constant K has the form K = [CO2]. Using a handbook to find density information about CaCO3(s) and CaO(s), show that the concentrations of the two solids (the number of moles contained in 1 L o
> Many sugars undergo a process called mutarotation, in which the sugar molecules interconvert between two isomeric forms, finally reaching an equilibrium between them. This is true for the simple sugar glucose, C6H12O6, which exists in solution in isomeri
> What is meant by the solubility product for a sparingly soluble salt? Choose a sparingly soluble salt and show how the salt ionizes when dissolved in water, and write the expression for its solubility product.
> When the volume of a vessel containing a gaseous equilibrium system is decreased, the of the gaseous substances present is initially increased.
> Addition of an inert substance (one that does not participate in the reaction) does not change the of an equilibrium.
> What is a homogeneous equilibrium system? Give an example of a homogeneous equilibrium reaction. What is a heterogeneous equilibrium system? Write two chemical equations that represent heterogeneous equilibria.
> According to Le Châtelier’s principle, when a large excess of a gaseous reactant is added to a reaction system at equilibrium, the amounts of products .
> Equilibria involving reactants or products in more than one state are said to be .
> Consider the equilibrium process depicted in Fig. 17.6. When does the equilibrium state occur? From figure 17.6: Liquid kvel is decreasing. Liquid level remains constant. At first there is a net transfer of molecules After a while, the amount of the
> At the point of chemical equilibrium, the rate of the forward reaction the rate of the reverse reaction.
> What does it mean to say that chemical equilibrium is a dynamic process?
> What does it mean to say that all chemical reactions are, to one extent or another, reversible?
> When a chemical system has reached equilibrium, the concentrations of all reactants and products remain with time.
> Equilibrium may be defined as the of two processes, one of which is the opposite of the other.
> A(n) speeds up a reaction without being consumed.
> The minimum energy required for molecules to react with each other is called the energy.
> What does it mean to say that an acid is weak in aqueous solution? What does this reveal about the ability of the acid’s anion to attract protons?
> Why does an increase in temperature favor an increase in the speed of a reaction?
> Before two molecules can react, chemists envision that the molecules must first collide with one another. Is collision among molecules the only consideration for the molecules to react with one another?
> A saturated solution of nickel(II) sulfide contains approximately 3.6 * 10-4 g of dissolved NiS per liter at 20 °C. Calculate the solubility product Ksp for NiS at 20 °C.
> Why are enzymes important? For example, what is the importance of the enzyme carbonic anhydrase in the body?
> Write the balanced chemical equation describing the dissolving of each of the following sparingly soluble salts in water. Write the expression for Ksp for each process. a. NiS(s) b. CuCO3(s) c. BaCrO4(s) d. Ag3PO4(s)
> Write the balanced chemical equation describing the dissolving of each of the following sparingly soluble salts in water. Write the expression for Ksp for each process. a. AgIO3(s) b. Sn(OH)2(s) c. Zn3(PO4)2(s) d. BaF2(s)
> Which of the following will affect the total amount of solute that can dissolve in a given amount of solvent? a. The solution is stirred. b. The solute is ground to fine particles before dissolving. c. The temperature changes.
> What is the special name given to the equilibrium constant for the dissolving of an ionic solute in water?
> For the reaction N2O4(g) ⇌ 2NO2(g) the equilibrium constant K has the value 8.1 * 10-3 at a particular temperature. If the concentration of N2O4(g) is found to be 5.4 * 10-4 M in the equilibrium system, what is the concentration of NO2(g) under these co
> An aqueous solution is to be prepared that will be 7.51% by mass ammonium nitrate. What mass of NH4NO3 and what mass of water will be needed to prepare 1.25 kg of the solution?
> 2H2O(g) ⇌ 2H2(g) + O2(g) K = 2.4 * 10-3 at a given temperature. At equilibrium it is found that [H2O( g)] = 1.1 * 10-1 M and [H2( g)] = 1.9 * 10-2 M. What is the concentration of O2( g) under these conditions?
> How does a catalyst work to speed up a chemical reaction?
> The equilibrium constant for the reaction H2(g) + F2(g) ⇌ 2HF(g) has the value 2.1 * 103 at a particular temperature. When the system is analyzed at equilibrium at this temperature, the concentrations of both H2( g) and F2( g) are found to be 0.0021 M.
> For the reaction CO2( g) + H2( g) ⇌ CO( g) + H2O( g) the equilibrium constant, K, has the value 5.21 * 10-3 at a particular temperature. If the system is analyzed at equilibrium at this temperature, it is found that [CO( g)] = 4.73 * 10-3 M, [H2O( g)] =
> For the reaction 2CO(g) + O2(g) ⇌ 2CO2(g) it is found at equilibrium at a certain temperature that the concentrations are [CO( g)] = 2.7 * 10-4 M, [O2( g)] = 1.9 * 10-3 M, and [CO2( g)] = 1.1 * 10-1 M. Calculate K for the reaction at this temperature.
> Consider the reaction SO2( g) + NO2( g) ⇌ SO3( g) + NO( g) Suppose it is found at a particular temperature that the concentrations in the system at equilibrium are as follows: [SO3( g)] = 4.99 * 10-5 M, [NO( g)] = 6.31 * 10-7 M, [SO2( g)] = 2.11 * 10-2
> For the reaction Br2( g) + 5F2( g) ⇌ 2BrF5( g) the system at equilibrium at a particular temperature is analyzed, and the following concentrations are found: [BrF5( g)] = 1.01 * 10-9 M, [Br2( g)] = 2.41 * 10-2 M, and [F2( g)] = 8.15 * 10-2 M. Calculate
> Suppose a reaction has the equilibrium constant K 5 1.7 * 10-8 at a particular temperature. Will there be a large or small amount of unreacted starting material present when this reaction reaches equilibrium? Is this reaction likely to be a good source o
> Plants synthesize the sugar dextrose according to the following reaction by absorbing radiant energy from the sun (photosynthesis). 6CO2(g) + 6H2O(g) ⇌ C6H12O6(s) + 6O2(g) Will an increase in temperature tend to favor or discourage the productio
> Old fashioned “smelling salts” consist of ammonium carbonate, (NH4)2CO3. The reaction for the decomposition of ammonium carbonate (NH4)2CO3(s) ⇌ 2NH3(g) + CO2(g) + H2O(g) is endothermic. What would be the effect on the position of this equilibrium if th
> A strong acid has a weak conjugate base, whereas a weak acid has a relatively strong conjugate base. Explain.
> How do the properties of a nonhomogeneous (heterogeneous) mixture differ from those of a solution? Give two examples of nonhomogeneous mixtures.
> When molecules collide, a certain minimum energy called the is needed for the reaction to occur.
> The reaction C2H2(g) + 2Br2(g) ⇌ C2H2Br4(g) is exothermic in the forward direction. Will an increase in temperature shift the position of the equilibrium toward reactants or products?
> Hydrogen gas, oxygen gas, and water vapor are in equilibrium in a closed container. Hydrogen gas is injected into the container, and the system is allowed to return to equilibrium. Which of the following occurs? Explain your answer. 2H2( g) + O2( g) ⇌ 2
> Hydrogen gas and chlorine gas in the presence of light react explosively to form hydrogen chloride H2( g) + Cl2( g) ⇌ 2HCl( g) The reaction is strongly exothermic. Would an increase in temperature for the system tend to favor or disfavor the production
> Consider the general reaction 2A( g) + B(s) ⇌ C( g) + 3D( g) ∆H = 1115 kJ/mol which has already come to equilibrium. Predict whether the equilibrium will shift to the left, will shift to the right, or will not be affected if the changes indicated belo
> Suppose the reaction system CH4(g) + 2O2(g) ⇌ CO2(g) + 2H2O(l) has already reached equilibrium. Predict the effect of each of the following changes on the position of the equilibrium. Tell whether the equilibrium will shift to the right, will shift to t
> For the reaction system P4(s) + 6F2( g) ⇌ 4PF3( g) which has already reached a state of equilibrium, predict the effect that each of the following changes will have on the position of the equilibrium. Tell whether the equilibrium will shift to the righ
> For the reaction system C(s) + H2O( g) ⇌ H2( g) + CO( g) which has already reached a state of equilibrium, predict the effect that each of the following changes will have on the position of the equilibrium. Tell whether the equilibrium will shift to th
> For an equilibrium involving gaseous substances, what effect, in general terms, is realized when the volume of the system is decreased?
> In your own words, describe what Le Châtelier’s principle tells us about how we can change the position of a reaction system at equilibrium.
> How is the strength of an acid related to the fact that a competition for protons exists in aqueous solution between water molecules and the anion of the acid?
> Indicate whether the stated equilibrium expression is correct for each of the following heterogeneous equilibria. For those expressions that are not correct, provide the correct expression along with an explanation. [N][Br}} [NBr3]? [Cu][H,O] [H] а.
> Write the equilibrium expression for each of the following heterogeneous equilibria. a. C(s) + H2O( g) ⇌ H2( g) + CO( g) b. H2O( l ) ⇌ H2O( g) c. 4B(s) + 3O2( g) ⇌ 2B2O3(s)
> Write the equilibrium expression for each of the following heterogeneous equilibria. a. 2LiHCO3(s) ⇌ Li2CO3(s) + H2O( g) + CO2( g) b. PbCO3(s) ⇌ PbO(s) + CO2( g) c. 4Al(s) + 3O2( g) ⇌ 2Al2O3(s)
> Write the equilibrium expression for each of the following heterogeneous equilibria. a. P4(s) + 6F2( g) ⇌4PF3( g) b. Xe( g) + 2F2( g) ⇌XeF4(s) c. 2SiO(s) + 4Cl2( g) ⇌2SiCl4( l ) + O2( g)
> Suppose that for the reaction 2N2O( g) + O2( g) ⇌ 4NO( g) it is determined, at a particular temperature, that the equilibrium concentrations are [NO( g)] = 0.00341 M, [N2O( g)] = 0.0293 M, and [O2( g)] = 0.0325 M. Calculate the value of K for the reacti
> At high temperatures, elemental nitrogen and oxygen react with each other to form nitrogen monoxide. N2(g) + O2(g) ⇌ 2NO(g) Suppose the system is analyzed at a particular temperature, and the equilibrium concentrations are found to be [N2] = 0.041 M, [O
> Ammonia, a very important industrial chemical, is produced by the direct combination of the following elements under carefully controlled conditions: N2(g) + 3H2(g) ⇌ 2NH3(g) Suppose, in an experiment, that the reaction mixture is analyzed after equilib
> For the simple reaction 2H2(g) + O2(g) 2H2O(l) list the types of bonds that must be broken and the types of bonds that must form for the chemical reaction to take place.
> Suppose that for the reaction PCl5( g) ⇌ PCl3( g) + Cl2( g) it is determined, at a particular temperature, that the equilibrium concentrations are [PCl5( g)] = 0.0711 M, [PCl3( g)] = 0.0302 M, and [Cl2( g)] = 0.0491 M. Calculate the value of K for the r
> Write the equilibrium expression for each of the following reactions. a. CO( g) + 2H2( g) ⇌ CH3OH( g) b. 2NO2( g) ⇌ 2NO( g) + O2( g) c. P4( g) + 6Br2( g) ⇌ 4PBr3( g)
> Calculate how many grams of solute and solvent are needed to prepare the following solutions. a. 525 g of 3.91% iron(III) chloride solution b. 225 g of 11.9% sucrose solution c. 1.45 kg of 12.5% sodium chloride solution d. 635 g of 15.1% potassium nit
> Write the equilibrium expression for each of the following reactions. a. NO2( g) + ClNO( g) ⇌ ClNO2( g) + NO( g) b. Br2( g) + 5F2( g) ⇌ 2BrF5( g) c. 4NH3( g) + 6NO( g) ⇌ 5N2( g) + 6H2O( g)
> Write the equilibrium expression for each of the following reactions. a. N2( g) + 3Cl2( g) ⇌ 2NCl3( g) b. H2( g) + I2( g) ⇌ 2HI( g) c. N2( g) + 2H2( g) ⇌ N2H4( g)
> Write the equilibrium expression for each of the following reactions. a. C2H6( g) + Cl2( g) ⇌ C2H5Cl(s) + HCl( g) b. 4NH3( g) + 5O2( g) ⇌ 4NO( g) + 6H2O( g) c. PCl5( g) ⇌ PCl3( g) + Cl2( g)
> Consider the following exothermic reaction at equilibrium: N2(g)+ 3H2(g) ⇌ 2NH3(g) Predict how the following changes affect the number of moles of each component of the system after equilibrium is reestablished by completing the tabl
> For the following endothermic reaction at equilibrium: 2SO3(g) ⇌ 2SO2(g) + O2(g) which of the following changes will increase the value of K? a. increasing the temperature b. decreasing the temperature c. removing SO3( g) (constant T) d. decreasi
> For the reaction: H2(g) + F2(g) ⇌ 2HF(g) K = 2.1 * 10-3 at a certain temperature. At equilibrium, [H2] = [F2] = 0.083 M. What is the concentration of HF under these conditions?
> The reaction H2(g) + I2(g) ⇌ 2HI(g) has Kp = 45.9 at 763 K. A particular equilibrium mixture at 763 K contains HI at a pressure of 4.94 atm and H2 at a pressure of 0.628 atm. Calculate the equilibrium pressure of I2( g) in this mixture.
> For the reaction: 3O2(g) ⇌ 2O3(g) K = 1.8 * 10-7 at a certain temperature. If at equilibrium [O2] = 0.062 M, calculate the equilibrium O3 concentration.
> Suppose that for a hypothetical reaction: A2(g) + 2B(g) ⇌ 2AB(g) It is determined that at a certain temperature the equilibrium concentrations are: [A2] = 0.0090, [B] = 0.940, and [AB] = 5.3 * 10-4. Calculate the numerical value of K for the reaction.
> At a particular temperature, a 3.50-L flask contains 1.16 moles of NH3, 2.40 moles of H2, and 1.14 moles of N2 in equilibrium. Calculate the value of K for the reaction 3H2(g) + N2(g) ⇌ 2NH3(g)
> What does it mean to say that an acid is strong in aqueous solution? What does this reveal about the ability of the acid’s anion to attract protons?
> For the reaction 2CO2( g) ⇌ 2CO( g) + O2( g) an analysis of an equilibrium mixture is performed. At a particular temperature, it is found that [CO] = 0.11 M, [O2] = 0.055 M, and [CO2] = 1.4 M. Calculate K for the reaction.
> Ammonia, a very important industrial chemical, is produced by the direct combination of the elements under carefully controlled conditions. N2(g) + 3H2(g) ⇌ 2NH3(g) Suppose, in an experiment, that the reaction mixture is analyzed after equilibrium is re
> When a reaction system has reached chemical equilibrium, the concentrations of the reactants and products no longer change with time. Why does the amount of product no longer increase, even though large concentrations of the reactants may still be pres e
> What are the catalysts in living cells called? Why are these biological catalysts necessary?
> What does the activation energy for a reaction represent? How is the activation energy related to whether a collision between molecules is successful?
