Chapter 6

You have a sugar solution (solution \(A\) ) with concentration \(x\) You pour one- fourth of this solution into a beaker, and add an equivalent volume of water (solution \(B\) ). a. What is the ratio of sugar in solutions \(A\) and \(B ?\) b. Compare the volumes of solutions \(A\) and \(B\). c. What is the ratio of the concentrations of sugar in solutions \(A\) and \(B ?\)

Why is it that when something gains electrons, it is said to be reduced? What is being reduced?

Consider separate aqueous solutions of HCl and \(\mathrm{H}_{2} \mathrm{SO}_{4}\) with the same molar concentrations. You wish to neutralize an aqueous solution of NaOH. For which acid solution would you need to add more volume (in milliliters) to neutralize the base? a. the HCI solution b. the \(\mathrm{H}_{2} \mathrm{SO}_{4}\) solution

You need to make \(150.0 \mathrm{mL}\) of a \(0.10-M\) NaCl solution. You have solid NaCl, and your lab partner has a \(2.5-M\) NaCl solution. Explain how you each make the 0.10-M NaCl solution.

The exposed electrodes of a light bulb are placed in a solution of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) in an electrical circuit such that the light bulb is glowing. You add a dilute salt solution, and the bulb dims. Which of the following could be the salt in the solution? a. \(\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\) c. \(\mathrm{K}_{2} \mathrm{SO}_{4}\) b. \(\mathrm{NaNO}_{3}\) d. \(\operatorname{Ca}\left(\mathrm{NO}_{3}\right)_{2}\) Justify your choices. For those you did not choose, explain why they are incorrect.

You have two solutions of chemical A. To determine which has the highest concentration of A (molarity), which of the following must you know (there may be more than one answer)? a. the mass in grams of \(A\) in each solution b. the molar mass of \(A\) c. the volume of water added to each solution d. the total volume of the solution Explain.

Which of the following must be known to calculate the molarity of a salt solution (there may be more than one answer)? a. the mass of salt added b. the molar mass of the salt c. the volume of water added d. the total volume of the solution Explain.

Of \(F_{2}, C F_{4}\) and \(S F_{2}\), which substance is most soluble in water? Explain.

A typical solution used in general chemistry laboratories is 3.0 \(M\) HCl. Describe, in detail, the composition of \(2.0 \mathrm{L}\) of a 3.0-M HCI solution. How would 2.0 L of a \(3.0-M \mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\) solution differ from the same quantity of the HCl solution?

A student wants to prepare \(1.00 \mathrm{L}\) of a \(1.00-M\) solution of NaOH (molar mass \(=40.00 \mathrm{g} / \mathrm{mol}\) ). If solid NaOH is available, how would the student prepare this solution? If \(2.00 \mathrm{M}\) NaOH is available, how would the student prepare the solution? To help ensure three significant figures in the NaOH molarity, to how many significant figures should the volumes and mass be determined?

List the formulas of three soluble bromide salts and three insoluble bromide salts. Do the same exercise for sulfate salts, hydroxide salts, and phosphate salts (list three soluble salts and three insoluble salts). List the formulas for six insoluble \(\mathrm{Pb}^{2+}\) salts and one soluble \(\mathrm{Pb}^{2+}\) salt.

When 1.0 mole of solid lead nitrate is added to 2.0 moles of aqueous potassium iodide, a yellow precipitate forms. After the precipitate settles to the bottom, does the solution above the precipitate conduct electricity? Explain. Write the complete ionic equation to help you answer this question.

What is an acid and what is a base? An acid-base reaction is sometimes called a proton-transfer reaction. Explain.

A student had 1.00 L of a \(1.00-M\) acid solution. Much to the surprise of the student, it took \(2.00 \mathrm{L}\) of \(1.00 \mathrm{M}\) NaOH solution to react completely with the acid. Explain why it took twice as much NaOH to react with all of the acid. In a different experiment, a student had \(10.0 \mathrm{mL}\) of 0.020 M HC1. Again, much to the surprise of the student, it took only \(5.00 \mathrm{mL}\) of \(0.020 \mathrm{M}\) strong base to react completely with the HCI. Explain why it took only half as much strong base to react with all of the HCl.

Differentiate between the following terms. a. species reduced versus the reducing agent b. species oxidized versus the oxidizing agent c. oxidation state versus actual charge

Show how each of the following strong electrolytes "breaks up" into its component ions upon dissolving in water by drawing molecular-level pictures. a. NaBr f. \(\mathrm{FeSO}_{4}\) b. \(\mathrm{MgCl}_{2}\) g. \(\mathrm{KMnO}_{4}\) c. \(\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}\) h. HCIO_ d. \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}\) i. \(\mathrm{NH}_{4} \mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\) (ammonium acetate) e. NaOH

Calcium chloride is a strong electrolyte and is used to "salt" streets in the winter to melt ice and snow. Write a reaction to show how this substance breaks apart when it dissolves in Water.

Commercial cold packs and hot packs are available for treating athletic injuries. Both types contain a pouch of water and a dry chemical. When the pack is struck, the pouch of water breaks, dissolving the chemical, and the solution becomes either hot or cold. Many hot packs use magnesium sulfate, and many cold packs use ammonium nitrate. Write reactions to show how these strong electrolytes break apart when they dissolve in water.

Calculate the molarity of each of these solutions. a. A 5.623 -g sample of NaHCO, is dissolved in enough water to make \(250.0 \mathrm{mL}\) of solution. b. A \(184.6-\mathrm{mg}\) sample of \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) is dissolved in enough water to make \(500.0 \mathrm{mL}\) of solution. c. A \(0.1025-\mathrm{g}\) sample of copper metal is dissolved in \(35 \mathrm{mL}\) of concentrated HNO_to form \(\mathrm{Cu}^{2+}\) ions and then water is added to make a total volume of \(200.0 \mathrm{mL}\). (Calculate the molarity of \(\mathrm{Cu}^{2+}\).)

A solution of ethanol \(\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)\) in water is prepared by dissolving 75.0 mL of ethanol (density \(=0.79 \mathrm{g} / \mathrm{cm}^{3}\) ) in enough water to make \(250.0 \mathrm{mL}\) of solution. What is the molarity of the ethanol in this solution?

Calculate the concentration of all ions present in each of the following solutions of strong electrolytes. a. 0.100 mole of \(\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}\) in \(100.0 \mathrm{mL}\) of solution b. 2.5 moles of \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) in 1.25 L of solution c. \(5.00 \mathrm{g}\) of \(\mathrm{NH}_{4} \mathrm{Cl}\) in \(500.0 \mathrm{mL}\) of solution d. \(1.00 \mathrm{g} \mathrm{K}_{3} \mathrm{PO}_{4}\) in \(250.0 \mathrm{mL}\) of solution

Calculate the concentration of all ions present in each of the following solutions of strong electrolytes. a. 0.0200 mole of sodium phosphate in \(10.0 \mathrm{mL}\) of solution b. 0.300 mole of barium nitrate in \(600.0 \mathrm{mL}\) of solution c. \(1.00 \mathrm{g}\) of potassium chloride in \(0.500 \mathrm{L}\) of solution d. \(132 \mathrm{g}\) of ammonium sulfate in \(1.50 \mathrm{L}\) of solution

Which of the following solutions of strong electrolytes contains the largest number of moles of chloride ions: \(100.0 \mathrm{mL}\) of \(0.30 \mathrm{M} \mathrm{AlCl}_{3}, 50.0 \mathrm{mL}\) of \(0.60 \mathrm{M} \mathrm{MgCl}_{2},\) or \(200.0 \mathrm{mL}\) of \(0.40 M\) NaCl?

Which of the following solutions of strong electrolytes contains the largest number of ions: \(100.0 \mathrm{mL}\) of \(0.100 \mathrm{M} \mathrm{NaOH}\), \(50.0 \mathrm{mL}\) of \(0.200 \mathrm{M} \mathrm{BaCl}_{2},\) or \(75.0 \mathrm{mL}\) of \(0.150 \mathrm{M} \mathrm{Na}_{3} \mathrm{PO}_{4} ?\)

What mass of NaOH is contained in \(250.0 \mathrm{mL}\) of a \(0.400 \mathrm{M}\) sodium hydroxide solution?

If \(10 . \mathrm{g}\) of \(\mathrm{AgNO}_{3}\) is available, what volume of \(0.25 \mathrm{M} \mathrm{AgNO}_{3}\) solution can be prepared?

Describe how you would prepare 2.00 L of each of the following solutions. a. \(0.250 \mathrm{M}\) NaOH from solid \(\mathrm{NaOH}\) b. \(0.250 M\) NaOH from \(1.00 M\) NaOH stock solution c. \(0.100 M K_{2} C r O_{4}\) from solid \(K_{2} C r O_{4}\) d. \(0.100 M K_{2} C r O_{4}\) from \(1.75 M K_{2} C r O_{4}\) stock solution

How would you prepare 1.00 L of a \(0.50-M\) solution of each of the following? a. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) from "concentrated" \((18 \mathrm{M})\) sulfuric acid b. HCl from "concentrated" (12 M) reagent c. \(\mathrm{NiCl}_{2}\) from the salt \(\mathrm{NiCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}\) d. HNO_ from "concentrated" (16 M) reagent e. Sodium carbonate from the pure solid

A solution is prepared by dissolving \(10.8 \mathrm{g}\) ammonium sulfate in enough water to make \(100.0 \mathrm{mL}\) of stock solution. A \(10.00-\) mL sample of this stock solution is added to \(50.00 \mathrm{mL}\) of water. Calculate the concentration of ammonium ions and sulfate ions in the final solution.

A solution was prepared by mixing \(50.00 \mathrm{mL}\) of \(0.100 \mathrm{M}\) HNO_and \(100.00 \mathrm{mL}\) of \(0.200 \mathrm{M}\) HNO \(_{3}\). Calculate the molarity of the final solution of nitric acid.

Calculate the sodium ion concentration when \(70.0 \mathrm{mL}\) of 3.0 \(M\) sodium carbonate is added to \(30.0 \mathrm{mL}\) of \(1.0 \mathrm{M}\) sodium bicarbonate.

Suppose \(50.0 \mathrm{mL}\) of \(0.250 \mathrm{M} \mathrm{CoCl}_{2}\) solution is added to 25.0 mL of 0.350 \(M \mathrm{NiCl}_{2}\) solution. Calculate the concentration, in moles per liter, of each of the ions present after mixing. Assume that the volumes are additive.

A standard solution is prepared for the analysis of fluoxymesterone \(\left(\mathrm{C}_{20} \mathrm{H}_{29} \mathrm{FO}_{3}\right),\) an anabolic steroid. A stock solution is first prepared by dissolving \(10.0 \mathrm{mg}\) of fluoxymesterone in enough water to give a total volume of \(500.0 \mathrm{mL}\). A \(100.0-\mu \mathrm{L}\) aliquot (portion) of this solution is diluted to a final volume of \(100.0 \mathrm{mL} .\) Calculate the concentration of the final solution in terms of molarity.

A stock solution containing \(\mathrm{Mn}^{2+}\) ions was prepared by dissolving 1.584 g pure manganese metal in nitric acid and diluting to a final volume of 1.000 L. The following solutions were then prepared by dilution: For solution \(A, 50.00 \mathrm{mL}\) of stock solution was diluted to \(1000.0 \mathrm{mL}\) For solution \(B, 10.00 \mathrm{mL}\) of solution \(A\) was diluted to \(250.0 \mathrm{mL}\). For solution \(C, 10.00 \mathrm{mL}\) of solution \(B\) was diluted to \(500.0 \mathrm{mL}\). Calculate the concentrations of the stock solution and solutions \(A, B,\) and \(C .\)

When the following solutions are mixed together, what precipitate (if any) will form? a. \(\operatorname{FeSO}_{4}(a q)+\operatorname{KCl}(a q)\) b. \(\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}(a q)+\mathrm{Ba}(\mathrm{OH})_{2}(a q)\) c. \(\mathrm{CaCl}_{2}(a q)+\mathrm{Na}_{2} \mathrm{SO}_{4}(a q)\) d. \(\mathrm{K}_{2} \mathrm{S}(a q)+\mathrm{Ni}\left(\mathrm{NO}_{3}\right)_{2}(a q)\)

When the following solutions are mixed together, what precipitate (if any) will form? a. \(\mathrm{Hg}_{2}\left(\mathrm{NO}_{3}\right)_{2}(a q)+\mathrm{CuSO}_{4}(a q)\) b. \(\mathrm{Ni}\left(\mathrm{NO}_{3}\right)_{2}(a q)+\mathrm{CaCl}_{2}(a q)\) c. \(\mathrm{K}_{2} \mathrm{CO}_{3}(a q)+\mathrm{MgI}_{2}(a q)\) d. \(\mathrm{Na}_{2} \mathrm{CrO}_{4}(a q)+\mathrm{AlBr}_{3}(a q)\)

Give an example how each of the following insoluble ionic compounds could be produced using a precipitation reaction. Write the balanced formula equation for each reaction. a. \(\mathrm{Fe}(\mathrm{OH})_{3}(s)\) c. \(\mathrm{PbSO}_{4}(s)\) b. \(\mathrm{Hg}_{2} \mathrm{Cl}_{2}(s)\) d. \(\mathrm{BaCrO}_{4}(s)\)

Write net ionic equations for the reaction, if any, that occurs when aqueous solutions of the following are mixed. a. ammonium sulfate and barium nitrate b. lead(II) nitrate and sodium chloride c. sodium phosphate and potassium nitrate d. sodium bromide and rubidium chloride e. copper(II) chloride and sodium hydroxide

Write net ionic equations for the reaction, if any, that occurs when aqueous solutions of the following are mixed. a. chromium(III) chloride and sodium hydroxide b. silver nitrate and ammonium carbonate c. copper(II) sulfate and mercury(I) nitrate d. strontium nitrate and potassium iodide

Separate samples of a solution of an unknown soluble ionic compound are treated with \(\mathrm{KCl}, \mathrm{Na}_{2} \mathrm{SO}_{4},\) and \(\mathrm{NaOH}\). A precipitate forms only when \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) is added. Which cations could be present in the unknown soluble ionic compound?

A sample may contain any or all of the following ions: \(\mathrm{Hg}_{2}^{2+}\) \(\mathrm{Ba}^{2+},\) and \(\mathrm{Mn}^{2+}\) a. No precipitate formed when an aqueous solution of \(\mathrm{NaCl}\) was added to the sample solution. b. No precipitate formed when an aqueous solution of \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) was added to the sample solution. c. A precipitate formed when the sample solution was made basic with NaOH. Which ion or ions are present in the sample solution?

What mass of \(\mathrm{Na}_{2} \mathrm{CrO}_{4}\) is required to precipitate all of the silver ions from \(75.0 \mathrm{mL}\) of a \(0.100-M\) solution of \(\mathrm{AgNO}_{3} ?\)

What volume of \(0.100 M \mathrm{Na}_{3} \mathrm{PO}_{4}\) is required to precipitate all the lead(II) ions from \(150.0 \mathrm{mL}\) of \(0.250 \mathrm{M} \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2} ?\)

What mass of solid aluminum hydroxide can be produced when 50.0 mL of \(0.200 M\) Al(NO_j) is added to 200.0 mL of \(0.100 M\) KOH?

What mass of barium sulfate can be produced when \(100.0 \mathrm{mL}\) of a 0.100-M solution of barium chloride is mixed with 100.0 mL of a 0.100-M solution of iron(III) sulfate?

What mass of solid AgBr is produced when \(100.0 \mathrm{mL}\) of 0.150 M AgNO_is added to \(20.0 \mathrm{mL}\) of \(1.00 \mathrm{M}\) NaBr?

What mass of silver chloride can be prepared by the reaction of \(100.0 \mathrm{mL}\) of \(0.20 \mathrm{M}\) silver nitrate with \(100.0 \mathrm{mL}\) of \(0.15 M\) calcium chloride? Calculate the concentrations of each ion remaining in solution after precipitation is complete.

A 100.0-mL aliquot of 0.200 \(M\) aqueous potassium hydroxide is mixed with \(100.0 \mathrm{mL}\) of \(0.200 \mathrm{M}\) aqueous magnesium nitrate. a. Write a balanced chemical equation for any reaction that occurs. b. What precipitate forms? c. What mass of precipitate is produced? d. Calculate the concentration of each ion remaining in solution after precipitation is complete.

A 1.42 -g sample of a pure compound, with formula \(\mathrm{M}_{2} \mathrm{SO}_{4}\) was dissolved in water and treated with an excess of aqueous calcium chloride, resulting in the precipitation of all the sulfate ions as calcium sulfate. The precipitate was collected, dried, and found to weigh \(1.36 \mathrm{g}\). Determine the atomic mass of \(\mathrm{M},\) and identify \(\mathrm{M}\).

You are given a \(1.50-g\) mixture of sodium nitrate and sodium chloride. You dissolve this mixture into \(100 \mathrm{mL}\) of water and then add an excess of 0.500 \(M\) silver nitrate solution. You produce a white solid, which you then collect, dry, and measure. The white solid has a mass of 0.64 \(1 \mathrm{g}\). a. If you had an extremely magnified view of the solution (to the atomic- molecular level), list the species you would see (include charges, if any). b. Write the balanced net ionic equation for the reaction that produces the solid. Include phases and charges. c. Calculate the percent sodium chloride in the original unknown mixture.