Why is the extraction of copper from pyrites more difficult than that from its oxide ore through reduction?
The Gibbs free energy of formation (ΔfG) of Cu2S is less than that of H2S and CS2. Therefore, H2 and C cannot reduce Cu2S to Cu.
On the other hand, the Gibbs free energy of formation of Cu2O is greater than that of CO. Hence, C can reduce Cu2O to Cu.
C(s) +Cu2O(s) → 2Cu(s) + CO(g)
Hence, the extraction of copper from its pyrite ore is difficult than from its oxide ore through reduction.
The reaction between A and B is first order with respect to A and zero order with respect to B. Fill in the blanks in the following table:
| Experiment |
A/ mol L - 1 |
B/ mol L - 1 |
Initial rate/mol L - 1 min - 1 |
| I | 0.1 | 0.1 |
2.0 × 10 - 2 |
| II | -- | 0.2 |
4.0 × 10 - 2 |
| III | 0.4 | 0.4 | -- |
| IV | -- | 0.2 |
2.0 × 10 - 2 |
NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:
The Gibbs free energy of formation (ΔfG) of Cu2S is less than that of H2S and CS2. Therefore, H2 and C cannot reduce Cu2S to Cu.
On the other hand, the Gibbs free energy of formation of Cu2O is greater than that...
Step-by-step explanation:
• The Gibbs free energy of formation (ΔfG) of Cu2S is less than that of H2S and CS2
• Therefore, H2 and C cannot reduce Cu2S to Cu
•
•
• On the other hand, the Gibbs free energy of formation of Cu2O is greater than that of CO
This question is important because it tests key concepts from the NCERT syllabus and is frequently asked in CBSE exams.
This question is based on core NCERT concepts explained in the chapter and should be revised thoroughly before exams.
Students often lose marks by skipping steps, writing incomplete explanations, or misunderstanding keywords used in the question.
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Student Discussion
⊝ for formation of Cr2O3 is -540 KJ mol-1
and that of Al2O3 -827 KJ mol-1
.
Is the reduction of Cr2O3 possible with Al ?
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