Extraction and Purification of Noble Metals

Questions and Answers

What factor primarily influences the rate of hydrolysis of organometallic compounds?

The nature of the organic ligand

Presence of carbon bonds with low polarity

Polarity of metal-carbon bonds (correct)

Size of the metal ion

What does the 18-electron rule help determine about transition metal complexes?

The stability of the complex (correct)

The maximum number of ligands that can be attached

The charge of the metal ion

The type of metal to use in synthesis

How many valence electrons do second row elements like carbon accommodate according to the octet rule?

12 electrons

6 electrons

8 electrons (correct)

10 electrons

What is required to fill all nine orbitals in the context of the 18-electron rule?

18 electrons from the metal and ligands combined Signup and view all the answers

What facilitates the nucleophilic attack by water on organometallic compounds?

Empty low-lying orbitals on the metal Signup and view all the answers

What is the oxidation state of the Re metal in the complex described?

+1 Signup and view all the answers

Which of the following denotes the oxidation state of Re in the complex?

Re(I) Signup and view all the answers

How many total electrons are present in the complex emphasized?

18e- Signup and view all the answers

What type of ligand is CH3− in the complex?

Anionic ligand Signup and view all the answers

What happens to the CO stretching frequency in IR as bonding modes change from terminal to μ2-bridging?

It decreases dramatically Signup and view all the answers

What is formed when the hybrid orbitals on the metal overlap with the filled hybrid orbital of carbon monoxide?

M←CO σ-bond Signup and view all the answers

With one anionic ligand present, what charge does the overall complex have?

Neutral charge Signup and view all the answers

In electron counting for complexes, what does the term 'neutral donor' refer to?

A ligand with no charge Signup and view all the answers

What is the role of zinc in the extraction of noble metals from their ores?

To separate the metallic forms from cyanide complexes Signup and view all the answers

Which process is used to purify nickel from impure sources?

The Mond process Signup and view all the answers

What is the significance of complex formation in qualitative analysis?

It aids in the color change for identification Signup and view all the answers

What type of catalyst is the Wilkinson catalyst?

A rhodium complex Signup and view all the answers

How does EDTA function in determining water hardness?

By forming stable complexes with calcium and magnesium ions Signup and view all the answers

What results from the reaction of Ni2+ ions with dimethyglyoxime?

Formation of colored insoluble precipitate Signup and view all the answers

In black and white photography, which complex ion is formed when washed with hypo solution?

[Ag(S2O3)2]3– Signup and view all the answers

What is Prussian blue commonly used for?

As a coloring agent in cosmetics and paints Signup and view all the answers

What type of orbitals overlap to form a π-bond in metal carbonyl complexes?

Filled dπ orbitals of the metal and antibonding pi orbitals of CO Signup and view all the answers

What is one of the uses of Fe(CO)5 in industrial applications?

Production of dietary supplements Signup and view all the answers

Which reaction involves alkene reacting with hydrogen gas and carbon monoxide using a catalyst?

Hydroformylation Signup and view all the answers

What is the oxidation state of iron in ferrocene?

+2 Signup and view all the answers

How many π-electrons are associated with each cyclopentadienyl (Cp) ring in ferrocene?

6 Signup and view all the answers

Which metal carbonyl complex is specifically mentioned for its role in hydrosilylation of olefins?

Co2(CO)8 Signup and view all the answers

What is a key characteristic of ferrocene that accounts for its stability?

Adherence to Hückel's aromatic rule Signup and view all the answers

Which industrial process uses nickel tetracarbonyl for the extraction and purification of nickel?

Mond process Signup and view all the answers

What is the main metal present in chlorophyll?

Mg2+ Signup and view all the answers

Which statement about chlorophyll a and chlorophyll b is true?

Chlorophyll a is more abundant than chlorophyll b in most plants. Signup and view all the answers

What feature distinguishes chlorophyll from heme?

A five-membered ring not present in heme. Signup and view all the answers

What happens to the chlorin ring without the presence of Mg2+?

It becomes fluorescent. Signup and view all the answers

Which property of chlorophyll contributes to its high light absorbance?

Polyene structure with alternating bonds. Signup and view all the answers

What role do light-harvesting complexes (LHCs) have in relation to chlorophyll?

They associate chlorophyll molecules with specific proteins. Signup and view all the answers

What characteristic allows chlorophyll to specifically absorb light during photosynthesis?

Its unusually high molar extinction coefficients. Signup and view all the answers

Why are chlorophylls green in color?

They absorb blue and red light, reflecting green. Signup and view all the answers

Study Notes

Organometallic Compounds and Hydrolysis

Hydrolysis of organometallic compounds occurs via nucleophilic attack by water.
Facilitating factors for hydrolysis include empty low-lying orbitals on the metal and metal-carbon bond polarity.
The rate of hydrolysis increases with greater polarity of the M-C bond.

The 18-electron Rule (EAN)

The 18-electron rule predicts the stability of d-block transition metal organometallic complexes.
Transition metals have one s, three p, and five d orbitals, totaling nine orbitals that can accommodate 18 electrons.
Stable compounds usually have a noble gas electron configuration.
Complexes should have no overall charge; anionic ligands are also considered in electron counting.

CO-Metal Bonding Interactions

σ-bond formation occurs through the overlap of empty hybrid orbitals on the metal with filled orbitals of carbon monoxide.
π-bonding involves back donation from filled d orbitals/hybrid dp orbitals of the metal to antibonding π orbitals on CO.

Metal-Carbonyl Complexes

Metal-carbonyls like nickel tetracarbonyl are important for industrial processes such as extraction and purification.
Carbonyl complexes enable simple transfer to pure metal forms in processes like the Mond process.
Metal carbonyls play roles in carbonylation reactions, impacting the production of aldehydes and other compounds.

Detection of Complex Formation

Qualitative analysis utilizes color changes in complex formation for inorganic ion identification.
Formation of colored precipitates with compounds like dimethyglyoxime aids in detecting specific metal ions.

Industrial Applications of Coordination Compounds

Coordination compounds serve as catalysts, exemplified by rhodium complex used for alkene hydrogenation.
Silver and gold electroplating is facilitated by metal cyanide complexes.
In photography, silver complexes are used to fix developed films.

Structure and Bonding in Ferrocene

Ferrocene consists of an iron center that is in the +2 oxidation state coordinated with cyclopentadienyl anions.
Gains stability from an 18-electron configuration unique to its bonding structure.
Features aromaticity due to the presence of 12 π-electrons shared with the metal.

Metals in Biology: Chlorophyll

Chlorophyll contains Mg2+ as the central metal ion in a polycyclic, planar structure resembling protoporphyrin.
The presence of a long phytol side chain attached to the chlorophyll structure aids in its functionality.
Chlorophyll a and b, found in chloroplasts, work together to maximize light absorption efficiency in visible light.

Absorption Characteristics of Chlorophyll

Chlorophylls exhibit high molar extinction coefficients, making them efficient at absorbing light essential for photosynthesis.
Different absorption spectra of chlorophyll a and b allow for complementary light absorption, contributing to the green color of plants.

Role of Magnesium in Chlorophyll

Magnesium is crucial for the stability of the chlorin ring; its absence leads to fluorescence, indicating loss of functionality in chlorophyll.

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Description

This quiz focuses on the processes involved in the extraction and purification of noble metals such as gold and silver from their ores. It also covers the role of complex formation in qualitative analysis, highlighting techniques for detecting metal complexes. Test your knowledge on chemical reactions and processes in inorganic chemistry.