Short Answer TypeDistinguish between paramagnetism and ferro-magnetism. How does ferro magnetism arise?
Long Answer Type(i) Breifly explain the physical properties of lanthanoids.
(ii) The chemical reactivity of lanthanoids resembles to which other elements of the periodic table.
Short Answer TypeHow does the acidified KMnO4 react with the following:
(a) Iron(II) solution, (b)SO32–, (c) Iodide (I–) ion, (d) oxalic acid, (e) NO2– (Nitrite ion).
Long Answer TypeExplain any one of following statement:
(i) The transition metals are well known for the formation of interstitial compounds.
(ii) The largest number of oxidation states are exhibited by mangnese in the first series of transition elements.
Short Answer TypeAnswer the following questions:
(i) Which element in the first series of transition elements does not exhibit variable oxidation states and why?
(ii) Why do actinoids in general exhibit a greater range of oxidation states than the Lanthanoids?
Long Answer Typei)Describe how potassium permanganate is made from pyrolusite. Write the chemical equations for the involved reactions.
ii) Describe with an example each of the oxidising actions of permanganate ion in alkaline and acidic media. What acid and alkali are usually used?
Pottassium Permanganate (KMnO4) is prepared from Pyrolusite ore (MnO2). The finely powdered Pyrolusite ore (MnO2) is fused with an alkali metal hydroxide like KOH in the presensce of air or an oxidizing agent like KNO3 to give the dark green potassium Manganate (K2MnO4). Potassium manganate disproportionate in a neutral or acidic solution to give potassium permanganate.
2 MnO2 + 4 KOH + O2 ----> 2K2MnO4 + 2H2O
3 MnO42- + 4H+ -----> 2MnO4- + MnO2 + 2H2O
Commercially potassium permanganate is prepared by the alkaline oxidative fusion ofPyrolusite ore (MnO2) followed by the electrolytic oxidation of manganate (4) ion.
2MnO2 + 4KOH + O2 ---> 2K2MnO4 + 2H2O
MnO42- ------(electrolytic oxidation)----> MnO4- + e-
ii) Equation Reduction of KMnO4 in acidic medium:
8H(+) + MnO4(2-) + 5e(-) ----------> Mn(2+) + 4H2O
In basic medium:
MnO4(-) + e(-) ------------> MnO4(2-)
Thus, you can see that oxidizing effect of KMnO4 is maximum in acidic medium and least in basic medium as in acidic medium the reduction in oxidation state of Mn is max while it is the least in basic medium.
H2SO4 and NaOH is used as acid and alkali.
Describe how potassium dichromate is made from chromate ore and give the equations for the chemical reactions involved.
Write balanced ionic equations for reacting ions to represent the action of acidified potassium dichromate solution on:
(a) Potassium iodide solution.
(b) Acidified ferrous sulphate solution. Write two uses of potassium dichromate.
Switch
