default_background
✕

Find the best tutors and institutes for Class 12 Tuition

Find Best Class 12 Tuition

Please select a Category.

Please select a Locality.

No matching category found.

No matching Locality found.

Q5.27(iv):
Discuss briefly giving an example in each case the role of coordination compounds in: extraction/metallurgy of metals.

Solution :

Theoretical Foundation: Coordination in Metallurgy

The extraction of metals via coordination chemistry relies on the formation of stable, soluble complex ions. By selectively forming a coordination complex, a target metal can be transitioned from its solid ore into an aqueous phase, effectively separating it from impurities (gangue). This is typically followed by a reduction process to isolate the pure metal. [Per Le Chatelierโ€™s Principle and Complexation Equilibrium].

Mechanism: The Cyanide Process for Gold and Silver

Gold ($Au$) and silver ($Ag$) are extracted from their native ores by leaching with dilute aqueous solutions of sodium cyanide ($NaCN$) in the presence of air or oxygen. The metal is oxidized and subsequently forms a stable water-soluble dicyanoaurate(I) complex.

Step 1: Oxidation and Complexation

$4Au(s) + 8CN^-(aq) + 2H_2O(aq) + O_2(g) \rightarrow 4[Au(CN)_2]^-(aq) + 4OH^-(aq)$

[Justification: The formation of the $[Au(CN)_2]^-$ complex provides a large formation constant ($K_f$), which drives the oxidation of metallic gold ($E^\circ_{cell} > 0$)]

Step 2: Recovery of Metal (Displacement)

The pure metal is recovered from the solution by adding a more electropositive metal such as zinc, which acts as a reducing agent.

$2[Au(CN)_2]^-(aq) + Zn(s) \rightarrow [Zn(CN)_4]^{2-}(aq) + 2Au(s)$

[Justification: Zinc displaces gold because the $[Zn(CN)_4]^{2-}$ complex is thermodynamically more stable than the gold complex, and zinc possesses a lower standard reduction potential than gold.]

Visual Representation of Coordination Geometry

Auโบ NCโป CNโป Linear Geometry of [Au(CN)โ‚‚]โป

Comparative Analysis Table

Stage Process Coordination Logic
Leaching Solubilization of Gold Conversion to soluble dicyanoaurate complex.
Separation Removal of Gangue Insoluble oxides/silicates filtered away.
Reduction Displacement Reduction via Zinc to form more stable $[Zn(CN)_4]^{2-}$.

Final Solution: Coordination compounds facilitate metallurgy by providing a selective solvent medium; for gold, the cyanide ion forms the stable $[Au(CN)_2]^-$ complex, allowing the gold to enter the aqueous phase and enabling its separation from insoluble gangue impurities.


More Questions from Class 12 Chemistry Coordination Compounds Exercises


CBSE Solutions for Class 12 Chemistry Coordination Compounds


Chapters in CBSE - Class 12 Chemistry


Top Tutors who teach Coordination Compounds

(9)
Top Tutor
locationImg Rajouri Garden, Delhi
experience 10 yrs of Exp students 1 student
greenClock 8 hrs of classes completed
rsIcon 1200 per hour
PGT Economics & Accountancy with more than 10 years of experience
Online Classes Online Classes
homeTutions Student's Home
regularClasses Tutor's home

I believe in delivering concepts and knowledge from the scratch so as to make the subject easy and relatable. My target is not only marks but rather developing an interest in the students for the subjects so as to have a better understanding and a good prospect for the future.

Skills: Economics , Accounts and more
Also teaches: Class 11 Tuition

(11)
Top Tutor
locationImg Karolan Ka Barh, Jaipur
experience 10 yrs of Exp students 2 students
greenClock 71 hrs of classes completed
rsIcon 700 per hour
Experience of 20 years in teaching
Online Classes Online Classes
regularClasses Tutor's home

With 12 years of dedicated teaching experience, I have consistently aimed to deliver high-quality education in the field of Commerce and related subjects. Holding a B.Com, M.Com, and B.Ed, along with being UGC NET qualified, I have taught at various academic levels, ensuring conceptual clarity and practical understanding for students. My teaching approach emphasizes student engagement, real-life applications of theoretical knowledge, and consistent academic growth. I have successfully prepared students for board exams and competitive assessments, fostering both academic excellence and confidence. Throughout my career, I have remained committed to continuous learning and adapting to modern teaching methodologies.

Kashmira Jat

Make complex topics easy to grasp and encourage the students and help in learning with such patient.

Skills: Accountancy , Business Studies and more
Also teaches: Class 11 Tuition, Hindi Language and more

(22)
Top Tutor
locationImg Maan, Pimpri-Chinchwad
experience 10 yrs of Exp students 6 students
greenClock 263 hrs of classes completed
rsIcon 1200 per hour
A friendly and passionate tutor with over 8 years of experience.
Online Classes Online Classes
homeTutions Student's Home
regularClasses Tutor's home

I have been teaching students for the past 10 years and have guided many to students in getting excellent results, showcasing their best performance. Concept-based teaching and an extra emphasis on every student needs has helped me provide a quality teaching environment to my students.

Also teaches: NEET-UG Coaching, SAT Coaching and more

(33)
Top Tutor
locationImg Shivaji Nagar, Nagpur
experience 15 yrs of Exp students 23 students
greenClock 1018 hrs of classes completed
rsIcon 650 per hour
learn easy & gain fast
Online Classes Online Classes

Withโ€“ 15 year of teaching Experience in IIT-JEE, NEET, CBSE & STATE BOARD to teach physics Teaching is my passion, by my knowledge and experience I teach the student to in simple and interesting way so he/ she understand the subject very well. I have 4 years of teaching experience in online mode So that i understand wery well the challenge of online teaching. So that i develop different teaching style in online mode to explain the topic which can easily understand by student. I can teach from basic level to expertise level in subject My achievement is I taught more then 5000 thousand of student in offline and more then 1000 student in online classes of reputed coaching. My many student are in IIT, NITs, doing MBBS, also they score very well in Board examination. In on-line mode I want explore my self . Share my knowledge and experience with student of different part of country and connecting myself with new edge of education system that emerging very fast. If student follow my point to point guidelines, take regular class, do home work, give regular test, follow my teaching notes and shares their problem, ask doubts then he will definitely improved to expert level. If you believe in yourself you have a strong will power Commited to study which save your travel time and money then go for on-line class. Do hard work, no shortcut for success, It requires dedication, and passion to prove Best of luck ๐Ÿคž๐Ÿ€ ....

Dhruva Choudhary

Really liked how vijay sir was able to explain difficult topics with relative ease and solved my doubts within the class itself.

Skills: Physics

(18)
Top Tutor
locationImg Banashankari, Bangalore
experience 4 yrs of Exp students 5 students
greenClock 271 hrs of classes completed
rsIcon 600 per hour
PhD Scholar and Commerce Postgraduate with 4+ years of Teaching Experience
Online Classes Online Classes

I am a commerce postgraduate from Pune University. Currently I am pursuing Ph.D in Commerce at one of the prestigious institutes for Commerce studies- Christ University, Bangalore. I have taught all the subjects of commerce to 11th & 12th Students since 4 years and BCom since 2 years. I have a good command on economics & accounts. I have a passion for teaching and have good understanding and practical exposure of these subjects. I also havd remotely worked as a Manager of Finance for a private firm in Maharashtra which makes me well versed in practical application of the subjects I teach.

Pranav

Maam is very understanding. Explains concepts differently from school teaching making easy to learn and remember.

Skills: Economics , Accounts and more
Also teaches: Class 9 Tuition, Class 10 Tuition and more

Other Subjects in CBSE - Class 12

Worksheet Icon

Download free CBSE - Class 12 Chemistry Coordination Compounds Exercises worksheets

Download Now

Find Best Class 12 Tuition ?

Find Now »