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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
The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co
Answer the following: Which element has the highest m.p?
Account for the following:
E° value for the Mn3+/Mn2+ couple is much more positive than that for Cr3+/Cr2+.
Out of Mn3+ and Cr3+, which is more paramagnetic and why ?
(Atomic nos. : Mn = 25, Cr = 24)
Why are Mn2+ compounds more stable than Fe2+ towards oxidation to their +3 state?
Complete and balance the following chemical equations
`Fe^(2+) + MnO_4^(-) + H^+ ->`
Explain why Zn2+ salts are white whereas Cu2+ salts are coloured.
Explain why does colour of KMnO4 disappear when oxalic acid is added to its solution in acidic medium.
EΘ of Cu is + 0.34V while that of Zn is – 0.76V. Explain.
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) \[\ce{Ni}\] |
Transition metals can act as catalysts because these can change their oxidation state. How does \[\ce{Fe(III)}\] catalyse the reaction between iodide and persulphate ions?
On the basis of the figure given below, answer the following questions:
- Why Manganese has lower melting point than Chromium?
- Why do transition metals of 3d series have lower melting points as compared to 4d series?
- In the third transition series, identify and name the metal with the highest melting point.
Which of the following is non-metallic?
The spin magnetic moment of cobalt in the compound Hg [Co(SCN)4] is:-
Account for the following:
Transition metals form alloys.
A transition element X has an electronic configuration [Ar]4s23d3. Predict its likely oxidation states.
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.)
What is the oxidation state of chromium in chromate ion and dichromate ion?
Explain the use of different transition metals as catalysts.
The compounds of \[\ce{Ti^4+}\] ions are colourless due to ______.
Describe the oxidising action of potassium dichromate and write the ionic equation for its reaction with iron (II) solution.
