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The enthalpy of transition of crustallin...

The enthalpy of transition of crustalline boron to amorphous boron at `1500^(@)C` is 0.4 kcal "mole"^(-1)`. Assuming at.wt of boron 10, the change in enthaplpy of transition 50 g boron from crystalline to amorphous form is

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`1 mol - 0.4 K.cal rArr 10 g - 0.4 K cal, 50 - ?`
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Borane is an electron deficient compound. It has only six valence eletons, so the boron atom lacks an octet. Acquiring an octet is the driving force for the unusual bonding structure found in boron compounds. As an electron deficient compound, BH_(3) is a strong electrophile, capable of adding to a double bond. This hydroboration of double bond is though to oC Cur in one step, with the boron atom adding to the less highly substituted end of the double bond. In transition state, the boron atom withdraws electrons from the pi bond and the carbon at theother end of the double bond acquires a partial positive charge. This positive charge is more stable on the more highly subsituted carbon atom. The second step is the oxidation of boron atom, removing it from carbon and replacing it with hydroxyl group by using H_(2)O_(2)//OH^(bar(..)) . The simultaneous addition of boron and hydrogen to the double bond leads to a syn addition. Oxidation of the trialkyl borane replaces boron with a hydroxyl group in the same stereochemical position. Thus, hydroboration of alkenen is an example of steropecific reaction, in which different steroisomers of starting compounds react to give different steroisomers of the product. CH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|)C-CH=CH_(2) underset((ii)H_(2)O_(2)//OH^(bar(..)))overset((i)BH_(3)//THF)rarrZ . Z is :

When a student mixed 50mL of 1M HCI and 150mL of 1M NaOH in a coffee cup calorimeter, the temperature of the resultant solution increases from 21^(@)C to 27.5^(@)C . Assuming that the calorimeter absorbs only a negligible quantity of heat, that the total volume of solution is 100mL , its density 1gmL^(-1) and that its specific heat is 4.18 J g^(-1) . calculate: a. The heat change during mixing. b. The enthalpy change for the reaction HCI(aq) +NaOH(aq) rarr NaCI(aq) +H_(2)O(aq)

Calculate total entropy change for the transition of 1 mole of solid sulphur from its monoclinic form to the rhombic form at 400 K, id DeltaH=-400J//"mole" for this transition and assume the surrounding to be in a bath of water at 27^(@)C

Calculate change in enthalpy when 2 moles of liquid water at 1 bar and 100^(@) C is coverted into steam at 2 bar and 300^(@) . Assume H_(2)O vapoures to behave ideally. [Latent heat of vaporisation of H_(2)O(l) at 1 bar and 100^(@) C id=s 10.8 kcal per mole] [R= 2cal//"mol" K ]

Light form a dicharge tube containing hydrogen atoms falls on the surface of a piece of sodium. The kinetic energy of the fastest photoelectrons emitted from sodium is 0.73 eV. The work function for sodium is 1.82 eV. Find (a) the energy of the photons causing the photoelectrons emission. (b) the quatum numbers of the two levels involved in the emission of these photons. (c ) the change in the angular momentum of the electron in the hydrogen atom, in the above transition, and (d) the recoil speed of the emitting atom assuming it to be at rest before the transition. (lonization potential of hydrogen is 13.6 eV.)

Light from a discharge tube containing hydrogen atoms falls on the surface of a piece of sodium . The kinetic energyof the fastest photonelectrons emittede from from sodium is 0.73 eV . The work function for sodium is 1.82 eCV find (a) the energy of the photons causing the photoelectric emission , (b) the quantum number of the two level inveloved in the emission of there photons, (c ) the change in the angular momentum of the electron in the hydrogen atom in the above transition and, (d)the recoll speed of emitted atom assuming it to be at rest before the transition. (lonization potential of hydrogen is 13.6 eV )

Calculate the total entropy change for the transition at 368K of 1mol of sulphur from the monoclinic to the rhombic solid state, if DeltaH=-401.7J ,mol^(-1) "for the transition". Assume the surroundings tio be an ice-water bath at 0^(@)C :

NARAYNA-THERMODYNAMICS-Level-VI
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  2. What is the entropy change for the conversion of one gram of ice to wa...

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  3. The enthalpy of transition of crustalline boron to amorphous boron at ...

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  4. At 0^(2)C, if enthalpy of fusion of ice is 1365 kcal/mol. The molar en...

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  5. A reaction becomes spontaneous only at 500K. If Delta H at 500 K is 3....

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  6. How much of the following are extensive properties ? Reasistance, Elec...

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  7. How much of the following are intensive properties ? Vapour pressure, ...

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  8. One mole of an ideal gas is heated at constant pressure from 0^(@)C to...

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  9. Water is boiled under a pressure of 1.0 atm. When an electric current ...

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  10. 14 g oxygen at 0^(@)C and 10 atm is subjected to reversible adiabatic ...

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  11. Calculate the equilibrium constant for the reaction given below at 400...

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  12. Calculate the free enegry change when 1mol of NaCI is dissolved in wat...

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  13. How much heat is required to change 10g ice at 0^(@)C to steam at 100^...

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  14. The vapour pressure of benzene is 1.53 xx 10^(4) Nm^(-2) at 303 K and ...

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  15. Molar heat capacity of CD(2)O (deuterated form of formaldehyde) at con...

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  16. 1 mol of an ideal gas at 25^(@)C is subjected to expand reversibly 10 ...

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  17. The standard enthalpy and entropy changes for the reaction in equilibr...

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  18. At 300K , the standard enthalpies of formation of C(6)H(5)COOH((s),CO(...

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  19. The heat of combusion of glycogen is about 476 kJ mol^(-1) of carbon. ...

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  20. Calculate DeltaH(f)^(@) for chloride ion from the following data : (...

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