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प्रश्न
Why does copper not replace hydrogen from acids?
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उत्तर
The value of standard reduction potential of copper (E° = + 0.34 V) is positive. Therefore, copper does not liberate hydrogen from acids.
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संबंधित प्रश्न
Explain why is Fe3+ more stable than Fe2+?
Which of the following cations are coloured in aqueous solutions and why ?
Sc3+, V3+, Ti4+, Mn2+ (At. Nos. Sc = 21, V = 23, Ti = 22, Mn = 25)
The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co
Answer the following: Which element is a strong oxidising agent in +3 oxidation state and why?
The `E_((M^(2+)//M))^Θ` value for copper is positive (+0.34 V). What is possibly the reason for this? (Hint: consider its high ΔaHΘ and low ΔhydHΘ)
How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.
Compare the stability of +2 oxidation state for the elements of the first transition series.
Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.
Explain why Mn2+ is more stable than Fe2+ towards oxidation to +3 state. (At. no. of Mn = 25, Fe = 26)
Highest oxidation state of manganese in fluoride is \[\ce{+4 (MnF4)}\] but highest oxidation state in oxides is \[\ce{+7 (Mn2O7)}\] because ______.
Match the properties given in Column I with the metals given in Column II.
| Column I (Property) | Column II (Metal) | |
| (i) | Element with highest second ionisation enthalpy |
(a) \[\ce{Co}\] |
| (ii) | Element with highest third ionisation enthalpy |
(b) \[\ce{Cr}\] |
| (iii) | \[\ce{M}\] in \[\ce{M(CO)6}\] is | (c) \[\ce{Cu}\] |
| (iv) | Element with highest heat of atomisation |
(d) \[\ce{Zn}\] |
| (e) \[\ce{Ni}\] |
A metallic ion 'M' reacts with chloride ion to form white precipitate which is readily soluble in aqueous ammonia. Identify 'M'?
Which does not belong to first transition series?
A complex in which dsp2 hybridisation takes place is ______.
Give reason for the following statement:
Physical and chemical properties of the 4d and 5d series of the transition elements are quite similar to expected.
The given graph shows the trends in melting points of transition metals:
Explain the reason why Cr has the highest melting point and manganese (Mn) has a lower melting point.
Consider the following standard electrode potential values:
\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\], E0 = +0.77 V
\[\ce{MnO^{-4}_{ (aq)} + 8H^+ + 5e^- -> Mn^{2+}_{ (aq)} + 4H2O_{(l)}}\], E0 = +1.51 V
What is the cell potential for the redox reaction?
Which of the following ions has the electronic configuration 3d6?
(Atomic number: Mn = 25, Co = 27, Ni = 28)
In order to protect iron from corrosion, which one will you prefer as a sacrificial electrode, Ni or Zn? Why? (Given standard electrode potentials of Ni, Fe and Zn are -0.25 V, -0.44 V and -0.76 V respectively.)
Give a reason for the following:
Transition metals possess a great tendency to form complex compounds.
For M2+/M and M3+/M2+systems, the EΘ values for some metals are as follows:
| Cr2+/Cr | −0.9 V |
| Mn2+/Mn | −1.2 V |
| Fe2+/Fe | −0.4 V |
| Cr3/Cr2+ | −0.4 V |
| Mn3+/Mn2+ | +1.5 V |
| Fe3+/Fe2+ | +0.8 V |
Use this data to comment upon:
The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.
