CHEMISTRY:MOLECULAR NATURE...-ALEKS 360
CHEMISTRY:MOLECULAR NATURE...-ALEKS 360
8th Edition
ISBN: 9781259916083
Author: SILBERBERG
Publisher: MCG
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Chapter 19, Problem 19.149P

(a)

Interpretation Introduction

Interpretation:

Value of [Co2+] and [EDTA4-] have to be calculated when 25.0ml 0.050M of [EDTA4-] is added to 50.0ml of 0.048M [Co2+] during titration.

Concept Introduction:

Chemical Equilibrium:

Chemical equilibrium is the process where the rate of forward reaction and the rate of backward reaction are equal.

Titration:

Titration is a quantitative chemical analysis to determine the concentration of an identified analyte.  The titrant is the reagent which is prepared as a standard solution of known concentration volume.  The titrant reacts with the analyte to determine the analyte’s concentration.  The volume of the titrant reacting with analyte is called the titration volume.

Formation constant:

A stability constant or formation constant is an equilibrium constant for the formation of a complex ion in the solution and it measures the strength of interaction between the reactants that forms the complex.

(a)

Expert Solution
Check Mark

Answer to Problem 19.149P

The concentrations calculated are [Co2+]=0.0153M and [EDTA4-]=5.346×10-17M.

Explanation of Solution

EDTA binds with metal ions to form complex ions and therefore it is used to determine the concentration of the metal ions.

In the problem it is given that the EDTA forms complex with Cobalt.

  Co2++EDTA4-[Co(EDTA)2-]

Given that solution contains 50.0ml of 0.048MCo2+.

Also 25.0ml of 0.050M EDTA4- is added.

As EDTA4- is added in limiting amount so excess Co2+ will remain in the solution.

So the number of moles for Co2+ and EDTA4- are calculated as,

  No.ofmolesofCo2+=volume×concentration=[50.0ml×0.048M]1000ml=0.0024moles

  No.ofmolesofEDTA4-=volume×concentration=[25.0ml×0.050M]1000ml=0.00125moles

Number of moles of Co(EDTA)2- formed is equal to number of moles of EDTA4- as it is the limiting reactant.

  No.ofmolesofCo(EDTA)2-=0.00125moles

  Excess no.ofmolesofCo2+=(0.00240.00125)moles=0.00115moles

  The total volume of solution = (25 ml of  EDTA4-+50.0mlofCo2+)=75mlofsolution

Hence, concentration of Co2+ calculated as,

  [Co2+]=0.00115mol(75×10-3)L=0.0153M

Hence, concentration of Co(EDTA)2- calculated as,

  [Co(EDTA)2-]=0.00125mol(75×10-3)L=0.0167M

Now, the formation constant for Co(EDTA)2- is calculated as,

  Kf=[Co(EDTA)2-][Co2+]×[EDTA4-]

Given as that logKf of [Co(EDTA)2-] is 16.31.

Kf For [Co(EDTA)2-]=2.0417×1016

To attain the equilibrium, there should be some amount of limiting reactant EDTA4- present in the solution and that is x (say).

If some amount EDTA4- is present then [Co2+] should be more and product complex [Co(EDTA)2-] should be less as some amount of EDTA4- is not taking part in equilibrium.

[Co2+]=0.0153+xM

[Co(EDTA)2-]=0.0167-xM

Thus from equation of Kf,

  [EDTA4-]=[Co(EDTA)2-][Co2+]×Kf

  x=(0.0167-x)M[(0.0153+x)M×2.0417×1016]=0.0167M[0.0153M×2.0417×1016]x=5.346×10-17M

Hence [Co2+]=0.0153M (x<<1, therefore x is neglected) and [EDTA4-]=5.346×10-17M.

(b)

Interpretation Introduction

Interpretation:

Value of [Co2+] and [EDTA4-] have to be calculated when 75.0ml0.050M of [EDTA4-] is added to 50.0ml of  0.048M [Co2+] during titration.

Concept Introduction:

Chemical Equilibrium:

Chemical equilibrium is the process where the rate of forward reaction and the rate of backward reaction are equal.

Titration:

Titration is a quantitative chemical analysis to determine the concentration of an identified analyte. The titrant is the reagent which is prepared as a standard solution of known concentration volume. The titrant reacts with the analyte to determine the analyte’s concentration. The volume of the titrant reacting with analyte is called the titration volume.

Formation constant:

A stability constant or formation constant is an equilibrium constant for the formation of a complex ion in the solution and it measures the strength of interaction between the reactants that forms the complex.

(b)

Expert Solution
Check Mark

Answer to Problem 19.149P

The value of [Co2+] and [EDTA4-] are respectively 8.707×1017M and 0.0108M.

Explanation of Solution

EDTA binds with metal ions to form complex ions and therefore it is used to determine the concentration of the metal ions.

In the problem it is given that the EDTA forms complex with Cobalt.

  Co2++EDTA4-[Co(EDTA)2-]

Given that solution contains  50.0ml of 0.048M Co2+.

75.0ml0.050M of EDTA4- is added.

As EDTA4- is added in excess amount so excess EDTA4- will remain in the solution and Co2+ will finish in the solution.

Hence the number of moles of Co2+ and EDTA4- are calculated as,

  No. of moles ofCo2+volume×concentration[50.0ml×0.048M]1000ml                               =0.0024 moles

  No. of moles of EDTA4- =volume×concentration                                   [75.0ml×0.050M]1000ml                                      =0.00375 moles

Number of moles of Co(EDTA)2- formed is equal to number of moles of Co2+ as it is the Limiting reactant.

  No. of moles of Co(EDTA)2- = 0.0024 moles

  Excess no. of moles of EDTA4- =(0.00375-0.0024)moles    =0.00135 moles

  The total volume of solution = (75 ml of  EDTA4-+50.0mlofCo2+)=125mlofsolution

Hence, concentration of EDTA4-,

  [EDTA4-]=0.00135mol(125×10-3)L=0.0108M

Hence, concentration of Co(EDTA)2-,

  [Co(EDTA)2-]=0.0024mol(125×10-3)L=0.0192M

Now, formation constant of Co(EDTA)2- is calculated as,

  Kf=[Co(EDTA)2-][Co2+]×[EDTA4-]

Given that logKf for [Co(EDTA)2-]=16.31.

Kf for [Co(EDTA)2-]=2.0417×1016

To attain the equilibrium some amount of the limiting reactant Co2+ must be present as unreacted in the solution and that is x (say).

Then the [EDTA4-] must be more and the forming complex [Co(EDTA)2-] must be ales as the whole Co2+ is not reacting.

Hence the concentration of [EDTA4-] and [Co(EDTA)2-] can be considered as,

  [EDTA4-]=0.0108+x

  [Co(EDTA)2-]=0.0192-x

Hence the concentration of Co2+ can be calculated as,

  [Co2+]=[Co(EDTA)2-][EDTA4-]×Kf

  x=(0.0192+x)M[(0.0108-x)M×2.0417×1016]

x=0.0192M[0.0108M×2.0417×1016]=8.707×1017M (x<<1)

Thus the values are respectively,

  [Co2+]=8.707×1017M

  [EDTA4-]=0.0108M (‘x’ is very small)

Hence, the value of [Co2+] and [EDTA4-] are respectively 8.707×1017M and 0.0108M.

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Chapter 19 Solutions

CHEMISTRY:MOLECULAR NATURE...-ALEKS 360

Ch. 19.3 - Prob. 19.6AFPCh. 19.3 - Prob. 19.6BFPCh. 19.3 - Prob. 19.7AFPCh. 19.3 - Prob. 19.7BFPCh. 19.3 - Prob. 19.8AFPCh. 19.3 - Prob. 19.8BFPCh. 19.3 - Prob. 19.9AFPCh. 19.3 - Prob. 19.9BFPCh. 19.3 - Prob. 19.10AFPCh. 19.3 - Prob. 19.10BFPCh. 19.3 - Prob. 19.11AFPCh. 19.3 - Prob. 19.11BFPCh. 19.3 - Prob. 19.12AFPCh. 19.3 - Prob. 19.12BFPCh. 19.3 - An environmental technician collects a sample of...Ch. 19.3 - A lake that has a surface area of 10.0 acres (1...Ch. 19.4 - Cyanide ion is toxic because it forms stable...Ch. 19.4 - Prob. 19.13BFPCh. 19.4 - Prob. 19.14AFPCh. 19.4 - Calculate the solubility of PbCl2 in 0.75 M NaOH....Ch. 19 - Prob. 19.1PCh. 19 - Prob. 19.2PCh. 19 - Prob. 19.3PCh. 19 - Prob. 19.4PCh. 19 - Prob. 19.5PCh. 19 - Prob. 19.6PCh. 19 - Prob. 19.7PCh. 19 - Prob. 19.8PCh. 19 - Does the pH increase or decrease with each of the...Ch. 19 - The scenes below depict solutions of the same...Ch. 19 - The scenes below show three samples of a buffer...Ch. 19 - What are the [H3O+] and the pH of a propanoic...Ch. 19 - What are the [H3O+] and the pH of a benzoic...Ch. 19 - Prob. 19.14PCh. 19 - Prob. 19.15PCh. 19 - Prob. 19.16PCh. 19 - Find the pH of a buffer that consists of 0.95 M...Ch. 19 - Prob. 19.18PCh. 19 - Prob. 19.19PCh. 19 - Prob. 19.20PCh. 19 - Find the pH of a buffer that consists of 0.50 M...Ch. 19 - A buffer consists of 0.22 M KHCO3 and 0.37 M...Ch. 19 - A buffer consists of 0.50 M NaH2PO4 and 0.40 M...Ch. 19 - What is the component concentration ratio,...Ch. 19 - Prob. 19.25PCh. 19 - Prob. 19.26PCh. 19 - Prob. 19.27PCh. 19 - Prob. 19.28PCh. 19 - A buffer that contains 0.40 M of a base, B, and...Ch. 19 - A buffer that contains 0.110 M HY and 0.220 M Y−...Ch. 19 - A buffer that contains 1.05 M B and 0.750 M BH+...Ch. 19 - A buffer is prepared by mixing 204 mL of 0.452 M...Ch. 19 - A buffer is prepared by mixing 50.0 mL of 0.050 M...Ch. 19 - Prob. 19.34PCh. 19 - Prob. 19.35PCh. 19 - Prob. 19.36PCh. 19 - Choose specific acid-base conjugate pairs to make...Ch. 19 - An industrial chemist studying bleaching and...Ch. 19 - Oxoanions of phosphorus are buffer components in...Ch. 19 - The scenes below depict the relative...Ch. 19 - Prob. 19.41PCh. 19 - What species are in the buffer region of a weak...Ch. 19 - Prob. 19.43PCh. 19 - Prob. 19.44PCh. 19 - Prob. 19.45PCh. 19 - Prob. 19.46PCh. 19 - Prob. 19.47PCh. 19 - Prob. 19.48PCh. 19 - Prob. 19.49PCh. 19 - Prob. 19.50PCh. 19 - Prob. 19.51PCh. 19 - Prob. 19.52PCh. 19 - Prob. 19.53PCh. 19 - Prob. 19.54PCh. 19 - Prob. 19.55PCh. 19 - Prob. 19.56PCh. 19 - Prob. 19.57PCh. 19 - Prob. 19.58PCh. 19 - Prob. 19.59PCh. 19 - Prob. 19.60PCh. 19 - Prob. 19.61PCh. 19 - Use figure 19.9 to find an indicator for these...Ch. 19 - Prob. 19.63PCh. 19 - Prob. 19.64PCh. 19 - Prob. 19.65PCh. 19 - Prob. 19.66PCh. 19 - Write the ion-product expressions for (a) silver...Ch. 19 - Write the ion-product expressions for (a)...Ch. 19 - Write the ion-product expressions for (a) calcium...Ch. 19 - Prob. 19.70PCh. 19 - The solubility of silver carbonate is 0.032 M at...Ch. 19 - Prob. 19.72PCh. 19 - Prob. 19.73PCh. 19 - The solubility of calcium sulfate at 30°C is 0.209...Ch. 19 - Prob. 19.75PCh. 19 - Prob. 19.76PCh. 19 - Prob. 19.77PCh. 19 - Calculate the molar solubility of Ag2SO4 in (a)...Ch. 19 - Prob. 19.79PCh. 19 - Prob. 19.80PCh. 19 - Prob. 19.81PCh. 19 - Prob. 19.82PCh. 19 - Prob. 19.83PCh. 19 - Write equations to show whether the solubility of...Ch. 19 - Prob. 19.85PCh. 19 - Prob. 19.86PCh. 19 - Prob. 19.87PCh. 19 - Does any solid PbCl2 form when 3.5 mg of NaCl is...Ch. 19 - Prob. 19.89PCh. 19 - Prob. 19.90PCh. 19 - Prob. 19.91PCh. 19 - A 50.0-mL volume of 0.50 M Fe(NO3)3 is mixed with...Ch. 19 - Prob. 19.93PCh. 19 - Prob. 19.94PCh. 19 - Prob. 19.95PCh. 19 - Write a balanced equation for the reaction of in...Ch. 19 - Prob. 19.97PCh. 19 - Prob. 19.98PCh. 19 - Prob. 19.99PCh. 19 - What is [Ag+] when 25.0 mL each of 0.044 M AgNO3...Ch. 19 - Prob. 19.101PCh. 19 - Prob. 19.102PCh. 19 - Prob. 19.103PCh. 19 - When 0.84 g of ZnCl2 is dissolved in 245 mL of...Ch. 19 - When 2.4 g of Co(NO3)2 is dissolved in 0.350 L of...Ch. 19 - Prob. 19.106PCh. 19 - A microbiologist is preparing a medium on which to...Ch. 19 - As an FDA physiologist, you need 0.700 L of formic...Ch. 19 - Tris(hydroxymethyl)aminomethane [(HOCH2)3CNH2],...Ch. 19 - Water flowing through pipes of carbon steel must...Ch. 19 - Gout is caused by an error in metabolism that...Ch. 19 - In the process of cave formation (Section 19.3),...Ch. 19 - Phosphate systems form essential buffers in...Ch. 19 - The solubility of KCl is 3.7 M at 20°C. 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