Advertisements
Advertisements
Question
How would you account for the following:
Cobalt (II) is stable in aqueous solutions, but in the presence of complexing reagents, it is easily oxidised.
Advertisements
Solution
In the presence of complexing reagents, the crystal field stabilization energy is greater than the third ionization enthalpy of cobalt. Thus, Co (II) is easily oxidized to Co (III).
RELATED QUESTIONS
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?
Calculate the ‘spin only’ magnetic moment of \[\ce{M^{2+}_{( aq)}}\] ion (Z = 27).
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 ion (octahedral).
Electronic configuration of Mn2+ is ____________.
Maximum oxidation state is shown by ____________.
Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds?
When a brown compound of manganese (A) is treated with \[\ce{HCl}\] it gives a gas (B). The gas taken in excess, reacts with \[\ce{NH3}\] to give an explosive compound (C). Identify compounds A, B and C.
A solution of \[\ce{KMnO4}\] on reduction yields either a colourless solution or a brown precipitate or a green solution depending on pH of the solution. What different stages of the reduction do these represent and how are they carried out?
Reactivity of transition elements decreases almost regularly from Sc to Cu. Explain.
Assertion: Separation of \[\ce{Zr}\] and \[\ce{Hf}\] is difficult.
Reason: Because \[\ce{Zr}\] and \[\ce{Hf}\] lie in the same group of the periodic table.
Assertion: The highest oxidation state of osmium is +8.
Reason: Osmium is a 5d-block element.
It has been observed that first ionization energy of 5 d series of transition elements are higher than that of 3d and 4d series, explain why?
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
Passing H2S gas into a mixture of Mn2+ and Ni2+, Cu2+, ions in an acidified aqueous solution precipitates.
Which of the following ions will exhibit colour in aqueous solution?
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.
Account for the following:
Ce4+ is a strong oxidising agent.
Consider the following standard electrode potential values:
\[\ce{Sn^{2+}_{ (aq)} + 2e^- -> Sn_{(s)}}\]; E0 = −0.14 V
\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\]; E0 = +0.77 V
What is the cell reaction and potential for the spontaneous reaction that occurs?
A pair of coloured ions is ______.
Account for the following:
Zirconium (Zr) and Hafnium (Hf) are difficult to separate.
