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. decreasing the volume (constant T) e. adding Ne( g) (constant T) f. adding SO2( g) (constant T) g. adding a catalyst (constant T)
> 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
> 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 ozo
> 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 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?
> For the reaction N2( g) + 3H2( g) 2NH3( g), list the types of bonds that must be broken and the type of bonds that must form for the chemical reaction to take place.
> Mercuric sulfide, HgS, is one of the least soluble salts known, with Ksp = 1.6 * 10-54 at 25 °C. Calculate the solubility of HgS in moles per liter and in grams per liter.
> Approximately 9.0 * 10-4 g of silver chloride, AgCl(s), dissolves per liter of water at 10 °C. Calculate Ksp for AgCl(s) at this temperature.
> As you learned in Chapter 7, most metal hydroxides are sparingly soluble in water. Write balanced chemical equations describing the dissolving of the following metal hydroxides in water. Write the expression for Ksp for each process. a. Cu(OH)2(s) b. C
> The equilibrium constant for the reaction 2NOCl(g) ⇌ 2NO(g) + Cl2(g) has the value 9.2 * 10-6 at a particular temperature. The system is analyzed at equilibrium, and it is found that the concentrations of NOCl( g) and NO( g) are 0.44 M and 1.5 * 10-3 M
> Calculate the percent by mass of solute in each of the following solutions. a. 6.11 mg of calcium chloride dissolved in 5.25 g of water b. 6.11 mg of calcium chloride dissolved in 52.5 g of water c. 6.11 g of calcium chloride dissolved in 52.5 g of wa
> For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g) K = 1.3 * 10-2 at a given temperature. If the system at equilibrium is analyzed and the concentrations of both N2 and H2 are found to be 0.10 M, what is the concentration of NH3 in the system?
> For the process CO(g) + H2O(g) ⇌ CO2(g) + H2(g) it is found that the equilibrium concentrations at a particular temperature are [H2] = 1.4 M, [CO2] = 1.3 M, [CO] = 0.71 M, and [H2O] = 0.66 M. Calculate the equilibrium constant K for the reaction under
> The reaction PCl3(l) + Cl2(g) ⇌ PCl5(s) liberates 124 kJ of energy per mole of PCl3 reacted. Will an increase in temperature shift the equilibrium position toward products or toward reactants?
> Suppose the reaction system 2NO(g) + O2(g) ⇌ 2NO2(g) 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 the left, o
> Write the equilibrium expression for each of the following heterogeneous equilibria. a. P4(s) + 5O2( g) ⇌ P4O10(s) b. CO2( g) + 2NaOH(s) ⇌ Na2CO3(s) + H2O( g) c. NH4NO3(s) ⇌ N2O( g) + 2H2O( g)
> Write the equilibrium expression for each of the following heterogeneous equilibria. a. 4Al(s) + 3O2( g) ⇌ 2Al2O3(s) b. NH3( g) + HCl( g) ⇌ NH4Cl(s) c. 2Mg(s) + O2( g) ⇌ 2MgO(s)
> Calculate the pH corresponding to each of the pOH values listed, and indicate whether each solution is acidic, basic, or neutral. a. pOH = 4.32 b. pOH = 8.90 c. pOH = 1.81 d. pOH = 13.1
> Of the following combinations, which would act as buffered solutions? a. HClO2 and KClO2 b. H2S and Na2S c. HCOOH and NaHCO d. HClO and HClO4
> In each of the following chemical equations, identify the conjugate acid–base pairs. a. HF(aq) + H2O(l) ⇌ F-(aq) 1 H3O+(aq) b. CN-(aq) + H2O(l) ⇌ HCN(aq) + OH-(aq) c. HCO3-(aq) + H2O(l) ⇌ H2CO3(aq) + OH-(aq)
> A(n) solution contains a conjugate acid–base pair and through this is able to resist changes in its pH.
> Calculate the percent by mass of solute in each of the following solutions. a. 2.14 g of potassium chloride dissolved in 12.5 g of water b. 2.14 g of potassium chloride dissolved in 25.0 g of water c. 2.14 g of potassium chloride dissolved in 37.5 g o
> A 0.20 M HCl solution contains M hydrogen ion and M chloride ion concentrations.
> A solution with pH = 9 has a (higher/lower) hydrogen ion concentration than a solution with pOH = 9.
> The number of in the logarithm of a number is equal to the number of significant figures in the number.
> Because of , even pure water contains measurable quantities of H+ and OH-.
> Draw the structure of the carboxyl group, -COOH. Show how a molecule containing the carboxyl group behaves as an acid when dissolved in water.
> Acetate ion, C2H3O2-, has a stronger affinity for protons than does water. Therefore, when dissolved in water, acetate ion behaves as a(n) .
> When organic compounds containing sulfur are burned, sulfur dioxide is produced. The amount of SO2 formed can be determined by the reaction with hydrogen peroxide: H2O2(aq) + SO2(g) H2SO4(aq) The resulting sulfuric acid is then
> A 50.00-mL sample of aqueous Ca(OH)2 requires 34.66 mL of a 0.944 M nitric acid for neutralization. Calculate the concentration (molarity) of the original solution of calcium hydroxide.
> A 450.0-mL sample of a 0.257 M solution of silver nitrate is mixed with 400.0 mL of 0.200 M calcium chloride. What is the concentration of Cl- in solution after the reaction is complete?
> A 500.0-mL sample of 0.200 M sodium phosphate is mixed with 400.0 mL of 0.289 M barium chloride. What is the mass of the solid produced?
> There is only one value of the equilibrium constant for a particular system at a particular temperature, but there are an infinite number of equilibrium positions. Explain.
> What volume of 0.100 M NaOH is required to precipitate all of the nickel(II) ions from 150.0 mL of a 0.249 M solution of Ni(NO3)2?
> A solution is prepared by dissolving 0.6706 g of oxalic acid (H2C2O4) in enough water to make 100.0 mL of solution. A 10.00-mL aliquot (portion) of this solution is then diluted to a final volume of 250.0 mL. What is the final molarity of the oxalic acid
> Consider the following generic reaction: 2A2B( g) ⇌ 2A2( g) + B2( g) Some molecules of A2B are placed in a 1.0-L container. As time passes, several snapshots of the reaction mixture are taken as illustrated below. Which illustration i
> Consider the reaction between 0.156 L of 0.105 M magnesium nitrate and 0.166 L of 0.106 M potassium hydroxide. a. What mass of precipitate will form? b. What is the concentration of nitrate ions left in solution after the reaction is complete?
> You mix 100.0 mL of 0.100 M calcium chloride with 100.0 mL of 0.100 M silver nitrate. What species are in solution when the reaction is complete? a. calcium ion, chloride ion, nitrate ion, water b. chloride ion, silver ion, nitrate ion, water c. calci
> Explain why the development of a vapor pressure above a liquid in a closed container represents an equilibrium. What are the opposing processes? How do we recognize when the system has reached a state of equilibrium?
> How many milliliters of 0.105 M NaOH are required to neutralize exactly 14.2 mL of 0.141 M H3PO4?
> Teeth and bones are composed, to a first approximation, of calcium phosphate, Ca3(PO4)2(s). The Ksp for this salt is 1.3 * 10-32 at 25 °C. Calculate the concentration of calcium ion in a saturated solution of Ca3(PO4)2.
> As you know from Chapter 7, most metal carbonate salts are sparingly soluble in water. Below are listed several metal carbonates along with their solubility products, Ksp. For each salt, write the equation showing the ionization of the salt in water, and
> For each of the following solutions, the mass of solute taken is indicated, as well as the total volume of solution prepared. Calculate the normality of each solution. a. 15.0 g of HCl; 500. mL b. 49.0 g of H2SO4; 250. mL c. 10.0 g of H3PO4; 100. mL
> In general terms, what does the equilibrium constant for a reaction represent? What is the algebraic form of the equilibrium constant for a typical reaction? What do square brackets indicate when we write an equilibrium constant?
> What volume of 0.250 M HCl is required to neutralize each of the following solutions? a. 25.0 mL of 0.103 M sodium hydroxide, NaOH b. 50.0 mL of 0.00501 M calcium hydroxide, Ca(OH)2 c. 20.0 mL of 0.226 M ammonia, NH3 d. 15.0 mL of 0.0991 M potassium
