Back
- Where in the periodic table are the most easily reduced elements found? The most easily oxidized?
Problem 115
- In each of the following instances, tell whether the substance gains electrons or loses electrons in a redox reaction. (a) An oxidizing agent (b) A reducing agent (c) A substance undergoing oxidation (d) A substance undergoing reduction
Problem 116
- Tell for each of the following substances whether the oxidation number increases or decreases in a redox reaction. (a) An oxidizing agent (b) A reducing agent (c) A substance undergoing oxidation (d) A substance undergoing reduction
Problem 117
Problem 118a
Which element is oxidized and which is reduced in each of the following reactions? (a)
Problem 118b
Which element is oxidized and which is reduced in each of the following reactions? (b)
Problem 119a
Which element is oxidized and which is reduced in each of the following reactions? (a)
Problem 119b
Which element is oxidized and which is reduced in each of the following reactions? (b)
Problem 120a
Use the activity series of metals (Table 4.5) to predict the outcome of each of the following reactions. If no reaction occurs, write NR. (a)
Problem 120b
Use the activity series of metals (Table 4.5) to predict the outcome of each of the following reactions. If no reaction occurs, write NR. (b)
Problem 120c
Use the activity series of metals (Table 4.5) to predict the outcome of each of the following reactions. If no reaction occurs, write NR. (c)
Problem 120d
Use the activity series of metals (Table 4.5) to predict the outcome of each of the following reactions. If no reaction occurs, write NR. (d)
Problem 121
Neither strontium (Sr) nor antimony (Sb) is shown in the activity series of Table 4.5. Based on their positions in the periodic table, which would you expect to be the better reducing agent? Will the following reaction occur? Explain.
Problem 122a
(a) Use the following reactions to arrange the elements A, B, C, and D in order of their decreasing ability as reducing agents:
Problem 122b
(b) Which of the following reactions would you expect to occur according to the activity series you established in part (a)?
Problem 123a
(a) Use the following reactions to arrange the elements A, B, C, and D in order of their decreasing ability as reducing agents:
Problem 123b
(b) Which of the following reactions would you expect to occur according to the activity series you established in part (a)?
- Iodine, I2, reacts with aqueous thiosulfate ion in neutral solution according to the balanced equation How many grams of I2 are present in a solution if 35.20 mL of 0.150 M Na2S2O3 solution is needed to titrate the I2 solution?
Problem 124
- How many milliliters of 0.250 M Na2S2O3 solution is needed for complete reaction with 2.486 g of I2 according to the equation in Problem 4.124?
Problem 125
- Dichromate ion, Cr2O7 2-, reacts with aqueous iron(II) ion in acidic solution according to the balanced equation What is the concentration of Fe2+ if 46.99 mL of 0.2004 M K2Cr2O7 is needed to titrate 50.00 mL of the Fe2+ solution?
Problem 126
- A volume of 18.72 mL of 0.1500 M K2Cr2O7 solution was required to titrate a sample of FeSO4 according to the equation in Problem 4.126. What is the mass of the sample?
Problem 127
- What is the molar concentration of As(III) in a solution if 22.35 mL of 0.100 M KBrO3 is needed for complete reaction with 50.00 mL of the As(III) solution? The balanced equation is:
Problem 128
- Standardized solutions of KBrO3 are frequently used in redox titrations. The necessary solution can be made by dissolving KBrO3 in water and then titrating it with an As(III) solution. What is the molar concentration of a KBrO3 solution if 28.55 mL of the solution is needed to titrate 1.550 g of As2O3? See Problem 4.128 for the balanced equation. (As2O3 dissolves in aqueous acid solution to yield H3AsO3: As2O3 + 3 H2OS 2 H3AsO3.)
Problem 129
- The metal content of iron in ores can be determined by a redox procedure in which the sample is first oxidized with Br2 to convert all the iron to Fe3+ and then titrated with Sn2+ to reduce the Fe3+ to Fe2+. The balanced equation is: What is the mass percent Fe in a 0.1875 g sample of ore if 13.28 mL of a 0.1015 M Sn2+ solution is needed to titrate the Fe3+?
Problem 130
- The concentration of the Sn2+ solution used in Problem 4.130 can be found by letting it react with a known amount of Fe2+. What is the molar concentration of an Sn2+ solution if 23.84 mL is required for complete reaction with 1.4855 g of Fe2O3?
Problem 131
- Alcohol levels in blood can be determined by a redox reaction with potassium dichromate according to the balanced equation What is the blood alcohol level in mass percent if 8.76 mL of 0.049 88 M K2Cr2O7 is required for complete reaction with a 10.002 g sample of blood?
Problem 132
- Calcium levels in blood can be determined by adding oxa-late ion to precipitate calcium oxalate, CaC2O4, followed by dissolving the precipitate in aqueous acid and titrating the resulting oxalic acid (H2C2O4) with KMnO4: How many milligrams of Ca2+ are present in 10.0 mL of blood if 21.08 mL of 0.000 988 M KMnO4 solution is needed for the titration?
Problem 133
- Assume that you have 1.00 g of a mixture of benzoic acid (Mol. wt. = 122) and gallic acid (Mol. wt. = 170)), both of which contain one acidic hydrogen that reacts with NaOH. On titrating the mixture with 0.500 M NaOH, 14.7 mL of base is needed to completely react with both acids. What mass in grams of each acid is present in the original mixture?
Problem 134
Problem 135a
A compound with the formula XOCl2 reacts with water, yielding HCl and another acid H2XO3, which has two acidic hydrogens that react with NaOH. When 0.350 g of XOCl2 was added to 50.0 mL of water and the resultant solution was titrated, 96.1 mL of 0.1225 M NaOH was required to react with all the acid. (a) Write a balanced equation for the reaction of XOCl2 with H2O.
Problem 135b
A compound with the formula XOCl2 reacts with water, yielding HCl and another acid H2XO3, which has two acidic hydrogens that react with NaOH. When 0.350 g of XOCl2 was added to 50.0 mL of water and the resultant solution was titrated, 96.1 mL of 0.1225 M NaOH was required to react with all the acid. (b) What are the atomic mass and identity of element X?
- A procedure for determining the amount of iron in a sample is to convert the iron to Fe2+ and then titrate it with a solu-tion of Ce(NH4)2(NO3)6: What is the mass percent of iron in a sample if 1.2284 g of the sample requires 54.91 mL of 0.1018 M Ce(NH4)2(NO3)6 for complete reaction?
Problem 136