/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 32 A coordination compound of cobal... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 21: Problem 32

A coordination compound of cobalt(III) contains four ammonia molecules, one sulfate ion, and one chloride ion. Addition of aqueous \(\mathrm{BaCl}_{2}\) solution to an aqueous solution of the compound gives no precipitate. Addition of aqueous \(\mathrm{AgNO}_{3}\) to an aqueous solution of the compound produces a white precipitate. Propose a structure for this coordination compound.

Short Answer

Expert verified
The coordination compound of cobalt(III) contains a central cobalt ion bonded to four ammonia molecules as monodentate ligands and a bidentate sulfate ion within the coordination sphere, making an octahedral geometry. The overall formula is \(\mathrm{[Co(SO_4)(NH_3)_4]Cl}\), with the chloride ion acting as a counter-ion to maintain charge neutrality.

Step by step solution

01

Examine the coordination complex

In a cobalt(III) coordination compound, the cobalt ion has a +3 charge. Since four ammonia molecules and one sulfate ion are coordinated to the cobalt, the sulfate is acting as a bidentate ligand, and the overall charge of the coordination sphere will be zero.
02

Identify the ligands and counter-ions

Since the sulfate ion is part of the coordination sphere and not a counter-ion, it must be bonded to the cobalt within the coordination sphere. This is supported by the fact that there is no precipitation upon the addition of BaCl2 solution. The chloride ion is the counter-ion for this compound, as indicated by the formation of a white precipitate after the addition of AgNO3.
03

Write the formula of the coordination compound

We can now write the formula for the cobalt(III) coordination compound. The cobalt ion, four ammonia molecules, and bidentate sulfate ion form the coordination sphere, resulting in a neutral charge. The chloride ion is a counter-ion, giving an overall formula of: \[ \mathrm{[Co(SO_4)(NH_3)_4]Cl} \]
04

Propose the structure of the coordination compound

Based on the given information and our formula, we can now propose the structure of the cobalt(III) coordination compound. The cobalt(III) ion, acting as the central metal atom, is bonded to four ammonia molecules as monodentate ligands, and to the bidentate sulfate ion within the coordination sphere. The overall structure would have a six-coordinate octahedral geometry around the cobalt metal center. The chloride ion is present outside the coordination sphere as a counter-ion to maintain overall charge neutrality.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Cobalt(III) Complexes
Cobalt(III) complexes are a fascinating part of coordination chemistry where cobalt exhibits a +3 oxidation state. In such a state, cobalt prefers to create coordination compounds due to its tendency to form stable bonds with surrounding ligands. These ligands can be molecules or ions that act as Lewis bases, donating electron pairs to the cobalt ion. In the exercise, cobalt is coordinated with four ammonia molecules and a sulfate ion. This combination forms a stable coordination sphere around the cobalt(III) ion. The positive charge of cobalt is essential as it allows cobalt to firmly hold onto the ligands by coordinating them in a specific geometric arrangement.
Bidentate Ligands
Bidentate ligands, like the sulfate ion in our exercise, are capable of forming two bonds with the central metal ion. They possess two donor atoms which can simultaneously attach to the metal center, creating a chelate. This doubly-chelating behavior enhances the stability of a complex.
  • Sulfate acts as a bidentate ligand in this case, wrapping around the cobalt ion in two places.
  • The term 'bidentate' comes from the Latin words 'bi-' meaning two, and 'dentate' meaning tooth-like, referring to the two points of attachment.
By forming such a connection, bidentate ligands influence the geometry and stability of coordination compounds significantly.
Counter-Ions
The role of counter-ions in coordination chemistry is to balance the charges of the coordination complexes. They are not directly bonded to the central metal ion but exist outside the coordination sphere. In the example from the exercise, the chloride ion serves as the counter-ion.
  • Counter-ions are essential for maintaining the electrical neutrality of a compound.
  • The presence of a white precipitate upon the addition of AgNO\(_3\) indicates that the chloride ion is free and not part of the coordination sphere.
In summary, counter-ions like chloride do not partake in the inner coordination environment of cobalt but complete the overall structural formula.
Octahedral Geometry
Octahedral geometry is a common structure around metal ions like cobalt(III) in coordination compounds, especially when six ligands are involved. This geometry resembles an octahedron, where the metal ion is at the center and the ligands are located at six vertices.
  • The arrangement provides maximum ligand interaction due to the angles of 90掳 between bonds, minimizing electron pair repulsion.
  • In the coordination compound described in our exercise, four ammonia molecules and one sulfate ion create this octahedral arrangement around the cobalt ion.
This geometric formation not only stabilizes the metallic center but also can influence the compound's properties such as color and reactivity. Understanding such structures is critical for grasping the behaviors of coordination compounds.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Draw all geometrical isomers of \(\mathrm{Pt}(\mathrm{CN})_{2} \mathrm{Br}_{2}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2} .\) Which of these isomers has an optical isomer? Draw the various optical isomers.

Which of the following crystal field diagram(s) is(are) correct for the complex given? a. \(\mathrm{Zn}\left(\mathrm{NH}_{3}\right)_{4}^{2+}\) (tetrahedral) b. \(\mathrm{Mn}(\mathrm{CN})_{6}{ }^{3-}\) (strong field) c. \(\mathrm{Ni}(\mathrm{CN})_{4}{ }^{2-}\) (square planar, diamagnetic)

Amino acids can act as ligands toward transition metal ions. The simplest amino acid is glycine \(\left(\mathrm{NH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right) .\) Draw a structure of the glycinate anion \(\left(\mathrm{NH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2}^{-}\right)\) acting as a bidentate ligand. Draw the structural isomers of the square planar complex \(\mathrm{Cu}\left(\mathrm{NH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2}\right)_{2}\)

Rank the following complex ions in order of increasing wavelength of light absorbed. $$ \mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}^{3+}, \mathrm{Co}(\mathrm{CN})_{6}^{3-}, \mathrm{CoI}_{6}^{3-}, \mathrm{Co}(\mathrm{en})_{3}^{3+} $$

Consider aqueous solutions of the following coordination compounds: \(\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6} \mathrm{I}_{3}, \mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{I}_{4}, \mathrm{Na}_{2} \mathrm{Pt} \mathrm{I}_{6}\), and \(\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{I}_{3} .\) If aqueous \(\mathrm{AgNO}_{3}\) is added to separate beakers containing solutions of each coordination compound, how many moles of AgI will precipitate per mole of transition metal present? Assume that each transition metal ion forms an octahedral complex.
See all solutions

Recommended explanations on Chemistry Textbooks

Ionic and Molecular Compounds

Read Explanation

Nuclear Chemistry

Read Explanation

Chemistry Branches

Read Explanation

Making Measurements

Read Explanation

Organic Chemistry

Read Explanation

Inorganic Chemistry

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.