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प्रश्न
Write balanced chemical equations for the conversion of `CrO_4^(2-)` to `Cr_2O_7^(2-)` in acidic medium and `Cr_2O_7^(2-)` to `CrO_4^(2-)`
in basic medium.
उत्तर
`K_2Cr_2O_7 + 2KOH -> 2K_2CrO_4 + H_2O`
`2K_2CrO_4 + 2HCl -> K_2Cr_2O_7 + 2KCl + H_2O`
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संबंधित प्रश्न
Complete the following chemical equations:
`(i) Cr_2O_7^(2-)+6Fe^(2+)+14H^+ ->`
`(ii) 2CrO_4^(2-)+2H^+ ->`
`(iii) 2MnO_4^-+5C_2O_4^(2-)+16H^+ ->`
The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co
Answer the following: Which element shows only +3 oxidation state?
How would you account for the following : Transition metals form coloured compounds
In the series Sc (Z = 21) to Zn (Z = 30), the enthalpy of atomization of zinc is the lowest, i.e., 126 kJ mol−1. Why?
How would you account for the irregular variation of ionization enthalpies (first and second) in the first series of the transition elements?
Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?
What may be the stable oxidation state of the transition element with the following d electron configurations in the ground state of their atoms?
3d3, 3d5, 3d8 and 3d4
What are the characteristics of the transition elements and why are they called transition elements?
In what way is the electronic configuration of the transition elements different from that of the non-transition elements?
Write down the number of 3d electrons in the following ion:
Cu2+
Indicate how would you expect the five 3d orbitals to be occupied for this hydrated ions (octahedral).
How would you account for the following?
Transition metals and their compounds act as catalysts.
Give reasons Iron has the higher enthalpy of atomization than that of copper.
How is potassium dichromate prepared from chrome iron ore?
Why is \[\ce{HCl}\] not used to make the medium acidic in oxidation reactions of \[\ce{KMnO4}\] in acidic medium?
The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
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) \[\ce{Ni}\] |
Assertion: The highest oxidation state of osmium is +8.
Reason: Osmium is a 5d-block element.
Mention the type of compounds formed when small atoms like H, C and N get trapped inside the crystal lattice of transition metals. Also give physical and chemical characteristics of these compounds.
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.
The standard electrode potentials of four elements A, B, C and D are – 3.05, – 1.66, – 0.40 and + 0.80. The highest chemical reactivity will be exhibited by
Which of the following statements is not correct?
Match List - I with List - II
| List - I | List - II | ||
| (a) | \[\ce{[Fe(CN)6]^3-}\] | (i) | 5.92 BM |
| (b) | \[\ce{[Fe(H2O)6]^3+}\] | (ii) | 0 BM |
| (c) | \[\ce{[Fe(CN)6]^4-}\] | (iii) | 4.90 BM |
| (d) | \[\ce{[Fe(H2O)6]^2+}\] | (iv) | 1.73 BM |
Choose the correct answer from the options given below.
Why is the `"E"_(("V"^(3+)//"V"^(2+)))^"o"` value for vanadium comparatively low?
Account for the following:
Sc3+ is colourless whereas Ti3+ is coloured in an aqueous solution.
Assertion (A): Transition metals have high enthalpy of atomisation.
Reason (R): Greater number of unpaired electrons in transition metals results in weak metallic bonding.
Which one among the following metals of the 3d series has the lowest melting point?
Assertion (A): Transition metals show their highest oxidation state with oxygen.
Reason (R): The ability of oxygen to form multiple bonds to metals.
Account for the following:
Eu2+ with electronic configuration [Xe]4f76s2 is a strong reducing agent.
