Question: Buffered solutions are mixtures of a weak

> Why does the amount of excess solid solute present in a solution not affect the amount of solute that ultimately dissolves in a given amount of solvent?

> Explain how the dissolving of an ionic solute in water represents an equilibrium process.

> Explain why the equivalent weight of H2SO4 is half the molar mass of this substance. How many hydrogen ions does each H2SO4 molecule produce when reacting with an excess of OH- ions?

> Suppose a reaction has the equilibrium constant K = 1.3 * 108. What does the magnitude of this constant tell you about the relative concentrations of products and reactants that will be present once equilibrium is reached? Is this reaction likely to be a

> Consider the exothermic reaction CO(g) + 2H2(g) ⇌ CH3OH(l) Predict three changes that could be made to the system that would decrease the yield of product over that produced by a system in which no change was made.

> What volume of 0.101 M HNO3 is required to neutralize each of the following solutions? a. 12.7 mL of 0.501 M NaOH b. 24.9 mL of 0.00491 M Ba(OH)2 c. 49.1 mL of 0.103 M NH3 d. 1.21 L of 0.102 M KOH

> What volume of 1.00 M NaOH is required to neutralize each of the following solutions? a. 25.0 mL of 0.154 M acetic acid, HC2H3O2 b. 35.0 mL of 0.102 M hydrofluoric acid, HF c. 10.0 mL of 0.143 M phosphoric acid, H3PO4 d. 35.0 mL of 0.220 M sulfuric a

> Despite HCl’s being a strong acid, the pH of 1.00 * 10-7 M HCl is not exactly 7.00. Can you suggest a reason why?

> A sample of sodium hydrogen carbonate solid weighing 0.1015 g requires 47.21 mL of a hydrochloric acid solution to react completely. HCl(aq) + NaHCO3(s) / NaCl(aq) + H2O(l) + CO2(g) Calculate the molarity of the hydrochloric acid solution.

> Strong bases are bases that completely ionize in water to produce hydroxide ion, OH-. The strong bases include the hydroxides of the Group 1 elements. For example, if 1.0 mole of NaOH is dissolved per liter, the concentration of OH- ion is 1.0 M. Calcula

> The “Chemistry in Focus” segment Water, Water Everywhere, But . . . discusses the desalinization of ocean water. Explain why many salts are soluble in water. Include molecular-level diagrams in your answer.

> The concepts of acid–base equilibria were developed in this chapter for aqueous solutions (in aqueous solutions, water is the solvent and is intimately involved in the equilibria). However, the Brønsted–Lowry acid–base theory can be extended easily to ot

> Aluminum ion may be precipitated from aqueous solution by addition of hydroxide ion, forming Al(OH)3. A large excess of hydroxide ion must not be added, however, because the precipitate of Al(OH)3 will redissolve as a soluble compound containing aluminum

> When aqueous solutions of lead(II) ion are treated with potassium chromate solution, a bright yellow precipitate of lead(II) chromate, PbCrO4, forms. How many grams of lead chromate form when a 1.00-g sample of Pb(NO3)2 is added to 25.0 mL of 1.00 M K2Cr

> Calcium oxalate, CaC2O4, is very insoluble in water. What mass of sodium oxalate, Na2C2O4, is required to precipitate the calcium ion from 37.5 mL of 0.104 M CaCl2 solution?

> Many metal ions are precipitated from solution by the sulfide ion. As an example, consider treating a solution of copper(II) sulfate with sodium sulfide solution: CuSO4(aq) + Na2S(aq) CuS(s) + Na2SO4(aq) What volume of 0.105 M Na2S s

> Which of the following combinations would act as buffered solutions? a. HCl and NaCl b. CH3COOH and KCH3COO c. H2S and NaHS d. H2S and Na2S

> The amount of nickel(II) present in an aqueous solution can be determined by precipitating the nickel with the organic chemical reagent dimethylglyoxime [CH3C(NOH)C(NOH)CH3, commonly abbreviated as “DMG”]. Ni2+(aq) + 2DMG(aq) Ni(DMG)2(

> Which component of a buffered solution consumes added strong base? Using your example from Exercise 60, show how this component would react with added NaOH.

> What is the effect on the equilibrium position if an exothermic reaction is carried out at a higher temperature? Does the net amount of product increase or decrease? Does the value of the equilibrium constant change if the temperature is increased? If so

> Ksp for magnesium carbonate, MgCO3, has a value 3.5 * 10-8 at 25 °C. Calculate the solubility of magnesium carbonate in mol/L and g/L at 25 °C.

> An oil spill spreads out on the surface of water, rather than dissolving in the water. Explain why.

> Calculate the hydrogen ion concentration, in moles per liter, for solutions with each of the following pH values. a. pH = 9.01 b. pH = 6.89 c. pH = 1.02 d. pH = 7.00

> Calculate the pH of each of the following solutions of strong acids. a. 1.21 * 10-3 M HNO3 b. 0.000199 M HClO4 c. 5.01 * 10-5 M HCl d. 0.00104 M HBr

> Calculate the hydrogen ion concentration and the pH of each of the following solutions of strong acids. a. 1.04 * 10-4 M HCl b. 0.00301 M HNO3 c. 5.41 * 10-4 M HClO4 d. 6.42 * 10-2 M HNO3

> Calculate the new molarity that results when 250. mL of water is added to each of the following solutions. a. 125 mL of 0.251 M HCl b. 445 mL of 0.499 M H2SO4 c. 5.25 L of 0.101 M HNO3 d. 11.2 mL of 14.5 M HC2H3O2

> Calculate the new molarity if each of the following dilutions is made. Assume the volumes are additive. a. 55.0 mL of water is added to 25.0 mL of 0.119 M NaCl solution b. 125 mL of water is added to 45.3 mL of 0.701 M NaOH solution c. 550. mL of wate

> Calculate the pH corresponding to each of the following hydroxide ion concentrations, and indicate whether each solution is acidic or basic. a. [OH-] = 4.85 * 10-5 M b. [OH-] = 3.96 * 10-7 M c. [OH-] = 1.22 * 10-10 M d. [OH-] = 5.33 * 10-12 M

> Calculate the pH corresponding to each of the hydroxide ion concentrations given below, and indicate whether each solution is acidic or basic. a. [OH-] = 4.73 * 10-4 M b. [OH-] = 5.99 * 10-1 M c. [OH-] = 2.87 * 10-8 M d. [OH-] = 6.39 * 10-3 M

> Calculate the hydrogen ion concentration, in moles per liter, for solutions with each of the following pH or pOH values. a. pOH = 4.99 b. pH = 7.74 c. pOH = 10.74 d. pH = 2.25

> Calculate the hydrogen ion concentration, in moles per liter, for solutions with each of the following pOH values. a. pOH = 4.95 b. pOH = 7.00 c. pOH = 12.94 d. pOH = 1.02

> Calculate the number of moles of each ion present in each of the following solutions. a. 10.2 mL of 0.451 M AlCl3 solution b. 5.51 L of 0.103 M Na3PO4 solution c. 1.75 mL of 1.25 M CuCl2 solution d. 25.2 mL of 0.00157 M Ca(OH)2 solution

> Given the general equation illustrating the reaction of the acid HA in water, HA(aq) + H2O(l) H3O+(aq) + A-(aq) explain why water is considered a base in the Brønsted-Lowry model.

> Calculate the number of moles of the indicated ion present in each of the following solutions. a. Na+ ion in 1.00 L of 0.251 M Na2SO4 solution b. Cl- ion in 5.50 L of 0.10 M FeCl3 solution c. NO3- ion in 100. mL of 0.55 M Ba(NO3)2 solution d. NH4+ io

> For each hydrogen ion concentration listed, calculate the pH of the solution as well as the concentration of hydroxide ion in the solution. Indicate whether each solution is acidic or basic. a. [H+] = 1.91 * 10-2 M b. [H+] = 4.83 * 10-7 M c. [H+] = 8.9

> For each hydrogen ion concentration listed, calculate the pH of the solution as well as the concentration of hydroxide ion in the solution. Indicate whether each solution is acidic or basic. a. [H+] = 4.76 * 10-8 M b. [H+] = 8.92 * 10-3 M c. [H+] = 7.0

> What mass of the indicated solute does each of the following solutions contain? a. 17.8 mL of 0.119 M CaCl2 b. 27.6 mL of 0.288 M KCl c. 35.4 mL of 0.399 M FeCl3 d. 46.1 mL of 0.559 M KNO3

> What mass of the indicated solute does each of the following solutions contain? a. 2.50 L of 13.1 M HCl solution b. 15.6 mL of 0.155 M NaOH solution c. 135 mL of 2.01 M HNO3 solution d. 4.21 L of 0.515 M CaCl2 solution

> How many moles of the indicated solute does each of the following solutions contain? a. 12.5 mL of 0.104 M HCl b. 27.3 mL of 0.223 M NaOH c. 36.8 mL of 0.501 M HNO3 d. 47.5 mL of 0.749 M KOH

> How many moles of the indicated solute does each of the following solutions contain? a. 4.25 mL of 0.105 M CaCl2 solution b. 11.3 mL of 0.405 M NaOH solution c. 1.25 L of 12.1 M HCl solution d. 27.5 mL of 1.98 M NaCl solution

> Calculate the pH corresponding to each of the following hydrogen ion concentrations, and indicate whether each solution is acidic, basic, or neutral. a. [H+] = 0.00512 M b. [H+] = 3.76 * 10-5 M c. [H+] = 5.61 * 10-10 M d. [H+] = 8.44 * 10-6 M

> Calculate the pH corresponding to each of the hydrogen ion concentrations given below, and indicate whether each solution is acidic or basic. a. [H+] = 4.02 * 10-3 M b. [H+] = 8.99 * 10-7 M c. [H+] = 2.39 * 10-6 M d. [H+] = 1.89 * 10-10 M

> Consider the reaction 2CO(g) + O2(g) ⇌ 2CO2(g) Suppose the system is already at equilibrium, and then an additional mole of CO2(g) is injected into the system at constant temperature. Does the amount of O2(g) in the system increase or decrease? Does th

> How do chemists envision reactions taking place in terms of the collision model for reactions? Give an example of a simple reaction and how you might envision the reaction’s taking place by means of a collision between the molecules.

> For a hydrogen ion concentration of 2.33 * 10-6 M, how many decimal places should we give when expressing the pH of the solution?

> Calculate the [H+] in each of the following solutions, and indicate whether the solution is acidic or basic. a. [OH-] = 2.32 * 10-4 M b. [OH-] = 8.99 * 10-10 M c. [OH-] = 4.34 * 10-6 M d. [OH-] = 6.22 * 10-12 M

> A conjugate acid–base pair consists of two substances related by the donating and accepting of a(n) .

> Of the following acids, which have relatively strong conjugate bases? a. HNO2 b. HCOOH c. HClO4 d. HNO3

> Calculate the concentration of all ions present when 0.160 g of MgCl2 is dissolved in enough water to make 100.0 mL of solution.

> Why do scientists tend to express the acidity of a solution in terms of its pH, rather than in terms of the molarity of hydrogen ion present? How is pH defined mathematically?

> A buffered solution is prepared containing acetic acid, HC2H3O2, and sodium acetate, NaC2H3O2, both at 0.5 M. Write a chemical equation showing how this buffered solution would resist a decrease in its pH if a few drops of aqueous strong acid HCl solutio

> If 27.5 mL of 3.5 * 10-2 N Ca(OH)2 solution is needed to neutralize 10.0 mL of nitric acid solution of unknown concentration, what is the normality of the nitric acid?

> Which component of a buffered solution is capable of combining with an added strong acid? Using your example from Exercise 60, show how this component would react with added HCl.

> A sodium dihydrogen phosphate solution was prepared by dissolving 5.0 g of NaH2PO4 in enough water to make 500. mL of solution. What are the molarity and normality of the resulting solution?

> Calculate the normality of each of the following solutions. a. 0.50 M acetic acid, HC2H3O2 b. 0.00250 M sulfuric acid, H2SO4 c. 0.10 M potassium hydroxide, KOH

> What two components make up a buffered solution? Give an example of a combination that would serve as a buffered solution.

> According to Arrhenius, produce hydrogen ions in aqueous solution, whereas produce hydroxide ions.

> What minimum volume of 16 M sulfuric acid must be used to prepare 750 mL of a 0.10 M H2SO4 solution?

> How many grams of Ba(NO3)2 are required to precipitate all the sulfate ion present in 15.3 mL of 0.139 M H2SO4 solution? Ba(NO3)2(aq) + H2SO4(aq) BaSO4(s) + 2HNO3(aq)

> What characteristic properties do buffered solutions possess?

> For each of the following solutions, the mass of solute is given, followed by the total volume of the solution prepared. Calculate the molarity of each solution. a. 5.59 g CaCl2; 125 mL b. 2.34 g CaCl2; 125 mL c. 8.73 g CaCl2; 125 mL d. 11.5 g CaCl2;

> When 10. L of water is added to 3.0 L of 6.0 M H2SO4, what is the molarity of the resulting solution? Assume the volumes are additive.

> Calculate the pH of each of the following solutions from the information given. a. [H+] = 3.42 * 10-10 M b. pOH = 5.92 c. [OH-] = 2.86 * 10-7 M d. [H+] = 9.11 * 10-2 M

> How many milliliters of 18.0 M H2SO4 are required to prepare 35.0 mL of 0.250 M solution?

> Calculate the pH of each of the following solutions from the information given. a. [H+] = 4.78 * 10-2 M b. pOH = 4.56 c. [OH-] = 9.74 * 10-3 M d. [H+] = 1.24 * 10-8 M

> Calcium carbonate, CaCO3, can be obtained in a very pure state. Standard solutions of calcium ion are usually prepared by dissolving calcium carbonate in acid. What mass of CaCO3 should be taken to prepare 500. mL of 0.0200 M calcium ion solution?

> The “Chemistry in Focus” segment Garden-Variety Acid– Base Indicators discusses acid–base indicators found in nature. What colors are exhibited by red cabbage juice under acid conditions? Under basic conditions?

> If 10. g of AgNO3 is available, what volume of 0.25 M AgNO3 solution can be prepared?

> How do the components of a conjugate acid–base pair differ from one another? Give an example of a conjugate acid–base pair to illustrate your answer.

> How many moles of the indicated solute does each of the following solutions contain? a. 1.5 L of 3.0 M H2SO4 solution b. 35 mL of 5.4 M NaCl solution c. 5.2 L of 18 M H2SO4 solution d. 0.050 L of 1.1 * 10-3 M NaF solution

> Water is the most common amphoteric substance, which means that, depending on the circumstances, water can behave either as an acid or as a base. Using HF as an example of an acid and NH3 as an example of a base, write equations for these substances reac

> For each of the following solutions, the mass of solute is given, followed by the total volume of the solution prepared. Calculate the molarity of each solution. a. 3.51 g NaCl; 25 mL b. 3.51 g NaCl; 50. mL c. 3.51 g NaCl; 75 mL d. 3.51 g NaCl; 1.00

> Concentrated hydrochloric acid is made by pumping hydrogen chloride gas into distilled water. If concentrated HCl contains 439 g of HCl per liter, what is the molarity?

> Complete the table for each of the following solutions: [H*] pH pOH [OH=] 0.0070 М HNO, 3.0 М КОН

> Choose pairs in which the species listed first is the conjugate base of the species listed second. a. S2-, HS- b. H+, OH- c. HBr, Br- d. NO2-, HNO2

> You add 40.0 mL of water to 60.0 mL of a 2.00 M calcium chloride solution. How many moles of calcium chloride are in the new solution?

> How many moles of each ion are present in 11.7 mL of 0.102 M Na3PO4 solution?

> A solution contains 7.5% by mass NaCl and 2.5% by mass KBr. What mass of each solute is contained in 125 g of the solution?

> What mass of KNO3 is required to prepare 125 g of 1.5% KNO3 solution?

> How many grams of Na2CO3 are contained in 500. g of a 5.5% by mass Na2CO3 solution?

> A sugar solution is prepared in such a way that it contains 10.% dextrose by mass. What quantity of this solution do we need to obtain 25 g of dextrose?

> A certain grade of steel is made by dissolving 5.0 g of carbon and 1.5 g of nickel per 100. g of molten iron. What is the mass percent of each component in the finished steel?

> Calculate the [OH-] in each of the following solutions, and indicate whether the solution is acidic or basic. a. [H+] = 1.02 * 10-7 M b. [H+] = 9.77 * 10-8 M c. [H+] = 3.41 * 10-3 M d. [H+] = 4.79 * 10-11 M

> What is an oxyacid? Write the formulas of three acids that are oxyacids. Write the formulas of three acids that are not oxyacids.

> Calculate the mass, in grams, of NaCl present in each of the following solutions. a. 11.5 g of 6.25% NaCl solution b. 6.25 g of 11.5% NaCl solution c. 54.3 g of 0.91% NaCl solution d. 452 g of 12.3% NaCl solution

> A solution is 0.1% by mass calcium chloride. Therefore, 100. g of the solution contains g of calcium chloride.

> Calculate the hydrogen ion concentration, in moles per liter, for solutions with each of the following pH values. a. pH = 8.34 b. pH = 5.90 c. pH = 2.65 d. pH = 12.6

> An experiment calls for 1.00 g of silver nitrate, but all that is available in the laboratory is a 0.50% solution of AgNO3. Assuming the density of the silver nitrate solution to be very nearly that of water because it is so dilute, determine how many mi

> The concentration of a solution of HCl is 33.1% by mass, and its density was measured to be 1.147 g/mL. How many milliliters of the HCl solution are required to obtain 10.0 g of HCl?

> Calculate the pOH corresponding to each of the pH values listed, and indicate whether each solution is acidic, basic, or neutral. a. pH = 1.02 b. pH = 13.4 c. pH = 9.03 d. pH = 7.20

> What volume of hydrogen chloride gas at STP is required to prepare 500. mL of 0.100 M HCl solution?

> Aqueous ammonia is typically sold by chemical supply houses as the saturated solution, which has a concentration of 14.5 mol/L. What volume of NH3 at STP is required to prepare 100. mL of concentrated ammonia solution?

> Strictly speaking, the solvent is the component of a solution that is present in the largest amount on a mole basis. For solutions involving water, water is almost always the solvent because there tend to be many more water molecules present than molecul

> Calculate the [OH-] in each of the following solutions, and indicate whether the solution is acidic or basic. a. [H+] = 4.01 * 10-4 M b. [H+] = 7.22 * 10-6 M c. [H+] = 8.05 * 10-7 M d. [H+] = 5.43 * 10-9 M

> Organic acids contain the carboxyl group Using acetic acid, CH3-COOH, and propionic acid, CH3CH2-COOH, write equations showing how the carboxyl group enables these substances to behave as weak acids when dissolved in water. `0-H

> Name four strong acids. For each of these, write the equation showing the acid dissociating in water.

> If 500. g of water is added to 75 g of 25% NaCl solution, what is the percent by mass of NaCl in the diluted solution?

> Write the conjugate base for each of the following. a. H3PO4 b. HCO3- c. HF d. H2SO4

> Write the conjugate acid for each of the following. a. NH3 b. NH2- c. H2O d. OH-

> In each of the following chemical equations, identify the conjugate acid–base pairs. a. CH3NH2 + H2O ⇌ CH3NH3+ + OH- b. CH3COOH + NH3 ⇌ CH3COO- + NH4+ c. HF + NH3 ⇌ F- + NH4+