Chemistry
Chemistry
9th Edition
ISBN: 9781133611097
Author: Steven S. Zumdahl
Publisher: Cengage Learning
bartleby

Concept explainers

bartleby

Videos

Textbook Question
Book Icon
Chapter 4, Problem 123CP

In most of its ionic compounds, cobalt is either Co(II) or Co(III). One such compound, containing chloride ion and waters of hydration, was analyzed, and the following results were obtained. A 0.256-g sample of the compound was dissolved in water, and excess silver nitrate was added. The silver chloride was filtered, dried, and weighed, and it bad a mass of 0.308 g. A second sample of 0.416 g of the compound was dissolved in water, and an excess of sodium hydroxide was added. The hydroxide salt was filtered and heated in a flame, forming cobalt(III) oxide. The mass of cobalt(III) oxide formed was 0.145 g.

a. What is the percent composition, by mass, of the compound?

b. Assuming the compound contains one cobalt ion per formula unit, what is the formula?

c. Write balanced equations for the three reactions described.

(a)

Expert Solution
Check Mark
Interpretation Introduction

Interpretation: The mass percentage of compound along with balanced chemical equation and formula has to be written.

Concept introduction: The mass percent of compound is given by the calculated mass of the compound to the total mass. The mass percent of compound is given by the formula,

Masspercent(in%)=Calculatedmass(ing)Totalmass(ing)

Answer to Problem 123CP

The mass percentage of Cobalt&Chlorine are 29.7%and24.8%

Explanation of Solution

Given:

Record the given info

Mass of sample containing chlorine = 0.256g

Mass of sample containing cobalt    = 0.416g

Mass of silver chloride                     = 0.308g

Mass of cobalt (III) oxide                 = 0.145g

The mass of samples containing chlorine and cobalt are recorded with the masses of silver chloride and cobalt (III) oxide as shown above.

To calculate the mass percent of Cl-

Molar mass of Chlorine          = 35.45g

Molar mass of silver chloride = 143.4g

Moles of Cl- = 0.308gAgCl×35.45gAg143.4gAgCl=0.0761gCl

Therefore, the mass percent of Cl- is,

Mass percent of Cl- = 0.0761g0.256g=29.7%

Mass percent of Cl- = 29.7%

The mass percent of Cl- is calculated by plugging in the values of moles of Cl- to the total mass of sample. The moles of Cl- is calculated by plugging in the values of mass of silver chloride and molar masses of chlorine and silver chloride. The mass percent of Cl- is 29.7%

To calculate the mass percent of Co2+

Molar mass of cobalt                   = 117.86g

Molar mass of cobalt (III) oxide = 165.86g we

Moles of Co2+ = 0.145gCo2O3×117.86gCo165.86gCo2O3=0.103gCo

Therefore, the mass percent of Co2+ is given by,

MasspercentofCo2+=0.103g0.416g×100=24.8%

Mass percent of Co2+ is 24.8%

The mass percent of Co2+ is calculated by plugging in the values of moles of Co2+ to the total mass of sample. The moles of Co2+ is calculated by plugging in the values of mass of silver chloride and molar masses of cobalt and cobalt (III) oxide. The mass percent of cobalt is 24.8% .

To calculate the mass percent of water

Molar mass of water = 18.02g

100-(24.8+27.90)=45.5%iswater

Assume that 100g of compound is,

45.5gH22.016gH18.02gH2O=5.09gHMasspercentofH+=5.09gH100.0g×100=5.09%

45.5gH216.00gO18.02gH2O=40.4gOMasspercentofO-=40.4gO100g×100=40.4%

The mass percent of hydrogen and oxygen is calculated by plugging in the molar mass of water and molar masses of hydrogen and oxygen to the total mass of the sample. The molar masses of hydrogen and oxygen were found to be 5.09% and 40.4%

Conclusion

The mass percentages of Co2+ , Cl- , H+ and O- were calculated using their respective moles and total masses of the samples. The mass percentages of Cl- and Co2+ were found to be 29.7% , 24.8% , 5.09% and 40.4% respectively.

(b)

Expert Solution
Check Mark
Interpretation Introduction

Interpretation: To calculate the empirical formula of the compound

Concept introduction: The representation of simplest positive integer of a atoms in a compound is called as empirical formula.

Answer to Problem 123CP

The formula for the compound is CoCl2.6H2O

Explanation of Solution

To calculate the empirical formula of the compound

Out of 100 g of compound, there are

24.8gCo×1mol58.93gCo=0.421mol29.7gCl×1mol35.45gCl=0.839mol5.09g1mol1.008gH=5.05mol40.4g1mol16.00gO=2.53mol

Dividing the moles by the smallest number,

The empirical formula of the compound becomes CoCl2.6H2O where, 6H2O the water molecules present in the compound

The empirical formula of the compound is calculated by calculating the mole ratio of individual elements divide by the smallest number. The empirical formula of the compound is found to be CoCl2.6H2O .

Conclusion

The empirical formula of the compound was calculated by using the mole ratio of individual elements divided by the smallest number. The empirical formula of the compound is found to be CoCl2.6H2O .

(c)

Expert Solution
Check Mark
Interpretation Introduction

Interpretation: To write the balanced equation of the precipitation reactions.

Concept introduction:

When two solutions containing soluble salts are mixed together, an insoluble salt so called precipitate is obtained and the reaction is called as precipitation reaction. These precipitation reactions help in the determination of various ions in the solution.’

Answer to Problem 123CP

CoCl2.6H2O(aq)+2AgNO3(aq)2AgCl(s)+Co(NO3)2(aq)+6H2O(l)CoCl2.6H2O(aq)+2NaOH(aq)Co(OH)2(s)+2NaCl(aq)+6H2O(l)Co(OH)2Co2O34Co(OH)2(s)+O2(g)2Co2O3(s)+4H2O(l)

This is redox reaction. Hence, an oxidizing agent is required and the oxidizing agent is O2

Explanation of Solution

To write the balanced equation of the precipitation reactions.

The reaction between cobalt chloride hexahydrate with base such as silver nitrate and sodium hydroxide yields precipitates of silver chloride and cobalt hydroxide with release of water and sodium chloride. The equation for this reaction can be given as,

CoCl2.6H2O(aq)+AgNO3(aq)AgCl(s)+Co(NO3)2(aq)+H2O(l)CoCl2.6H2O(aq)+NaOH(aq)Co(OH)2(s)+NaCl(aq)+H2O(l)Co(OH)2Co2O3Co(OH)2(s)+O2(g)Co2O3(s)+H2O(l)

Cobalt hydroxide oxidizes to cobalt (III) oxide and water.

Two moles of silver nitrate are required to react with cobalt chloride hexahydrate to give 2 moles of silver chloride as precipitate with side products being cobalt nitrate and water. Cobalt nitrate being water soluble remains inside the solution, thus precipitating silver chloride out of the solution.

Two moles of sodium hydroxide are required to react with cobalt chloride hexahydrate to give 2 moles of cobalt hydroxide with sodium chloride and water. Sodium chloride being soluble in water, dissociates as spectator ions thus remaining in the solution and a precipitate of cobalt hydroxide is precipitated out.

Cobalt hydroxide on heating is oxidized to cobalt (III) oxide with water.

The balanced form of these equations can be given as,

CoCl2.6H2O(aq)+2AgNO3(aq)2AgCl(s)+Co(NO3)2(aq)+6H2O(l)CoCl2.6H2O(aq)+2NaOH(aq)Co(OH)2(s)+2NaCl(aq)+6H2O(l)Co(OH)2Co2O34Co(OH)2(s)+O2(g)2Co2O3(s)+4H2O(l)

The reaction of heating cobalt hydroxide is oxidation-reduction reaction, where oxygen is used as oxidizing agent and cobalt (III) oxide is obtained.

Conclusion

The given reactions were found to be precipitation reaction and moles on the reactant and the product were obtained. The reaction of heating cobalt hydroxide is oxidation-reduction reaction, where oxygen is used as oxidizing agent to oxidized cobalt hydroxide to cobalt (III) oxide. The balanced equations are,

CoCl2.6H2O(aq)+2AgNO3(aq)2AgCl(s)+Co(NO3)2(aq)+6H2O(l)CoCl2.6H2O(aq)+2NaOH(aq)Co(OH)2(s)+2NaCl(aq)+6H2O(l)Co(OH)2Co2O34Co(OH)2(s)+O2(g)2Co2O3(s)+4H2O(l)

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!

Chapter 4 Solutions

Chemistry

Ch. 4 - Assume you have a highly magnified view of a...Ch. 4 - You have a solution of table salt in water. What...Ch. 4 - You have a sugar solution (solution A) with...Ch. 4 - You add an aqueous solution of lead nitrate to an...Ch. 4 - Order the following molecules from lowest to...Ch. 4 - Why is it that when something gains electrons, it...Ch. 4 - Consider separate aqueous solutions of HCl and...Ch. 4 - Prob. 8ALQCh. 4 - Prob. 9ALQCh. 4 - The exposed electrodes of a light bulb are placed...Ch. 4 - Differentiate between what happens when the...Ch. 4 - A typical solution used in general chemistry...Ch. 4 - Prob. 15QCh. 4 - A student wants to prepare 1.00 L of a 1.00-M...Ch. 4 - List the formulas of three soluble bromide salts...Ch. 4 - When 1.0 mole of solid lead nitrate is added to...Ch. 4 - What is an acid and what is a base? An acid-base...Ch. 4 - A student had 1.00 L of a 1.00-M acid solution....Ch. 4 - Differentiate between the following terms. a....Ch. 4 - How does one balance redox reactions by the...Ch. 4 - Prob. 23ECh. 4 - Match each name below with the following...Ch. 4 - Calcium chloride is a strong electrolyte and is...Ch. 4 - Commercial cold packs and hot packs are available...Ch. 4 - Calculate the molarity of each of these solutions....Ch. 4 - A solution of ethanol (C2H5OH) in water is...Ch. 4 - Calculate the concentration of all ions present in...Ch. 4 - Prob. 30ECh. 4 - Prob. 31ECh. 4 - Prob. 32ECh. 4 - Prob. 33ECh. 4 - If 10. g of AgNO3 is available, what volume of...Ch. 4 - A solution is prepared by dissolving 10.8 g...Ch. 4 - A solution was prepared by mixing 50.00 mL of...Ch. 4 - Calculate the sodium ion concentration when 70.0...Ch. 4 - Suppose 50.0 mL of 0.250 M CoCl2 solution is added...Ch. 4 - Prob. 41ECh. 4 - A stock solution containing Mn2+ ions was prepaned...Ch. 4 - On the basis of the general solubility rules given...Ch. 4 - On the basis of the general solubility rules given...Ch. 4 - When the following solutions are mixed together,...Ch. 4 - When the following solutions are mixed together,...Ch. 4 - For the reactions in Exercise 47, write the...Ch. 4 - For the reactions in Exercise 48, write the...Ch. 4 - Write the balanced formula and net ionic equation...Ch. 4 - Give an example how each of the following...Ch. 4 - Write net ionic equations for the reaction, if...Ch. 4 - Write net ionic equations for the reaction, if...Ch. 4 - Separate samples of a solution of an unknown...Ch. 4 - A sample may contain any or all of the following...Ch. 4 - What mass of Na2CrO4 is required to precipitate...Ch. 4 - What volume of 0.100 M Na3PO4 is required to...Ch. 4 - What mass of iron(III) hydroxide precipitate can...Ch. 4 - What mass of silver chloride can be prepared by...Ch. 4 - A 100.0-mL aliquot of 0.200 M aqueous potassium...Ch. 4 - A 1.42-g sample of a pure compound, with formula...Ch. 4 - You are given a 1.50-g mixture of sodium nitrate...Ch. 4 - Write the balanced formula, complete ionic, and...Ch. 4 - Write the balanced formula, complete ionic, and...Ch. 4 - Write the balanced formula equation for the...Ch. 4 - Prob. 68ECh. 4 - What volume of each of the following acids will...Ch. 4 - Prob. 70ECh. 4 - Hydrochloric acid (75.0 mL of 0.250 M) is added to...Ch. 4 - A student mixes four reagents together, thinking...Ch. 4 - A 25.00-mL sample of hydrochloric acid solution...Ch. 4 - A 10.00-mL sample of vinegar, an aqueous solution...Ch. 4 - What volume of 0.0200 M calcium hydroxide is...Ch. 4 - A 30.0-mL sample of an unknown strong base is...Ch. 4 - A student titrates an unknown amount of potassium...Ch. 4 - The concentration of a certain sodium hydroxide...Ch. 4 - Assign oxidation states for all atoms in each of...Ch. 4 - Assign the oxidation state for nitrogen in each of...Ch. 4 - Assign oxidatioo numbers to all the atoms in each...Ch. 4 - Specify which of the following are...Ch. 4 - Specify which of the following equations represent...Ch. 4 - Consider the reaction between sodium metal and...Ch. 4 - Consider the reaction between oxygen (O2) gas and...Ch. 4 - Balance each of the following oxidationreduction...Ch. 4 - Balance each of the following oxidationreduction...Ch. 4 - You wish to prepare 1 L of a 0.02-M potassium...Ch. 4 - The figures below are molecular-level...Ch. 4 - Prob. 91AECh. 4 - Prob. 92AECh. 4 - Using the general solubility rules given in Table...Ch. 4 - Consider a 1.50-g mixture of magnesium nitrate and...Ch. 4 - A 1.00-g sample of an alkaline earth metal...Ch. 4 - A mixture contains only NaCl and Al2(SO4)3. A...Ch. 4 - A mixture contains only NaCl and Fe(NO3)3. A...Ch. 4 - A student added 50.0 mL of an NaOH solution to...Ch. 4 - Some of the substances commonly used in stomach...Ch. 4 - Acetylsalicylic acid is the active ingredient in...Ch. 4 - When hydrochloric acid reacts with magnesium...Ch. 4 - A 2.20-g sample of an unknown acid (empirical...Ch. 4 - Carminic acid, a naturally occurring red pigment...Ch. 4 - Chlorisondamine chloride (C14H20Cl6N2) is a drug...Ch. 4 - Saccharin (C7H5NO3S) is sometimes dispensed in...Ch. 4 - Douglasite is a mineral with the formula 2KC1...Ch. 4 - Many oxidationreduction reactions can be balanced...Ch. 4 - The blood alcohol (C2H5OH) level can be determined...Ch. 4 - Calculate the concentration of all ions present...Ch. 4 - A solution is prepared by dissolving 0.6706 g...Ch. 4 - For the following chemical reactions, determine...Ch. 4 - What volume of 0.100 M NaOH is required to...Ch. 4 - Prob. 114CWPCh. 4 - A 450.0-mL sample of a 0.257-M solution of silver...Ch. 4 - The zinc in a 1.343-g sample of a foot powder was...Ch. 4 - A 50.00-mL sample of aqueous Ca(OH)2 requires...Ch. 4 - When organic compounds containing sulfur are...Ch. 4 - Assign the oxidation state for the element Listed...Ch. 4 - A 10.00-g sample consisting of a mixture of sodium...Ch. 4 - The units of parts per million (ppm) and parts per...Ch. 4 - In the spectroscopic analysis of many substances,...Ch. 4 - In most of its ionic compounds, cobalt is either...Ch. 4 - Polychlorinated biphenyls (PCBs) have been used...Ch. 4 - Consider the reaction of 19.0 g of zinc with...Ch. 4 - A mixture contains only sodium chloride and...Ch. 4 - Prob. 127CPCh. 4 - Zinc and magnesium metal each react with...Ch. 4 - You made 100.0 mL of a lead(II) nitrate solution...Ch. 4 - Consider reacting copper(II) sulfate with iron....Ch. 4 - Consider an experiment in which two burets, Y and...Ch. 4 - Complete and balance each acid-base reaction. a....Ch. 4 - What volume of 0.0521 M Ba(OH)2 is required to...Ch. 4 - A 10.00-mL sample of sulfuric acid from an...Ch. 4 - A 0.500-L sample of H2SO4 solution was analyzed by...Ch. 4 - A 6.50-g sample of a diprotic acid requires 137.5...Ch. 4 - Citric acid, which can be obtained from lemon...Ch. 4 - Prob. 138CPCh. 4 - It took 25.06 0.05 mL of a sodium hydroxide...Ch. 4 - Prob. 140IPCh. 4 - In a 1-L beaker, 203 mL of 0.307 M ammonium...Ch. 4 - Prob. 142IPCh. 4 - The unknown acid H2X can be neutralized completely...Ch. 4 - Three students were asked to find the identity of...Ch. 4 - You have two 500.0-mL aqueous solutions. Solution...
Knowledge Booster
Background pattern image
Chemistry
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
Chemistry
Chemistry
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Cengage Learning
Text book image
Chemistry: An Atoms First Approach
Chemistry
ISBN:9781305079243
Author:Steven S. Zumdahl, Susan A. Zumdahl
Publisher:Cengage Learning
Text book image
Chemistry
Chemistry
ISBN:9781133611097
Author:Steven S. Zumdahl
Publisher:Cengage Learning
Text book image
Introductory Chemistry: A Foundation
Chemistry
ISBN:9781337399425
Author:Steven S. Zumdahl, Donald J. DeCoste
Publisher:Cengage Learning
Text book image
Chemistry: Principles and Reactions
Chemistry
ISBN:9781305079373
Author:William L. Masterton, Cecile N. Hurley
Publisher:Cengage Learning
Text book image
Living By Chemistry: First Edition Textbook
Chemistry
ISBN:9781559539418
Author:Angelica Stacy
Publisher:MAC HIGHER
Acid-Base Titration | Acids, Bases & Alkalis | Chemistry | FuseSchool; Author: FuseSchool - Global Education;https://www.youtube.com/watch?v=yFqx6_Y6c2M;License: Standard YouTube License, CC-BY