Short Answer TypeCalculate the enthalpy change for the reaction: C(graphite) + 2H2(g) CH4(g)
Given that:
(i) C(graphite) + O2 (g) → CO2 (g) Δ H f °= - 393.5 KJ mol-1
(ii) H2(g) + 0.5 O2 (g) → H2O(l) ΔH = -285.8 KJ mol-1
(iii) CH4 (g) + 2O2(g) → CO2 (g) + 2H2O(l) ΔH°f = - 890.3 KJ mol-1
(i) A solution of O. 1(N)KCl offers a resistance of 245 ohms. Calculate the specific conductance and the equivalent conductance of the solution if the cell constant is 0.571 cm-1
(ii) Compare the crystals of copper and diamond giving one similarity and one difference.
(iii) If the standard free energy change for a reaction is found to be zero, what is the value of the equilibrium constant for the reaction?
Siemens ozonizer: On a large scale, 03 is prepared by passing silent electric discharge through the air. Siemens’ and Halske ozone used for this purpose is shown in Figure and is known as Siemens and Halske ozonizer. It consists of about six to eight porcelain or glass cylinders, each surrounding a cylinder of aluminium fitted in a metal box. The aluminium cylinders are connected to an insulator at the bottom f the metal box and therefore, these are insulated from the box. Cold water is kept flowing into the box which after cooling the cylinders goes out. The metal box is earthed and the aluminium cylinders are raised to a potential of nearly 10,000 volts. Air is passed through the annular space between the aluminium cylinders and porcelain cylinders and is thus subjected to the action of electric discharges and comes out in the form o ozonized air as shown in diagrams. Preparation of pure ozone. In order to obtain pure ozone from ozonised oxygen, it is cooled with liquid air when ozone (b.pt. 160.6 K) condenses as a deep blue liquid while oxygen (b.pt. 90 K) remains as a gas at this temperature. Pure ozone is obtained by the fractional distillation of deep blue liquid obtained.
Pure ozone can also be obtained by passing ozonised oxygen through silica gel which adsorbs ozone, leaving behind oxygen gas. The absorbed ozone recovered by passing nitrogen or argon through the silica get.
Give balanced equations for each of the following reactions:
(i) Chlorine and hot concentrated caustic soda.
(ii) Sulphur dioxide and acidified potassium permanganate.
(i)Name the type of isomerism shown by the following pair of compounds: [PtCl2/NH3)4IBr2 and [PtBr2(NH3)4]Cl2
Give a chemical test to distinguish between the given pair of isomers.
(ii) Draw the geometrical isomers exhibited by the compound [PtCl2(NH3)2].
Write the formulae of the following co-ordination compounds:
(i) tetracarbonyl nickel (0)
(ii) potassium dicyanoargentate (1)
Account for the following:
(i) SF6 exists but OF6 does not, though both oxygen and sulphur belong to the same group in the Periodic table.
(ii) Zn+2 compounds are white in colour but Cu+2 compounds are coloured, though both zinc and copper are d-block elements.
(i)To which class of compounds does IF7 belong? What is the structure of the molecule?
(ii) Give the balanced equation for the preparation of silver nitrate in the laboratory.
How can the following conversions be brought about:
(i) Ethylamine to methylamine
(ii) Benzene to acetanilide
(iii) 2 Propanol to acetoxime
Give one example for each of the following name reactions:
(i) Hell Volhard Zelinsky (HVZ) reaction,
(ii) Clemmensen’s reduction.
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