Question

Questions:

1. The densities of ice and water at 0 °C are 0.9168 and 0.9998 g cm–3,respectively. If ∆H for the fusion process at atmospheric pressure is 6.025 kJmol–1,

   1. What is ∆U?

   2. How much work is done on the system?

2. For each of the following processes, state which of the quantities ∆U, ∆H, and ∆S are equal to zero. Explain with logical reasoning.

   1. Isothermal reversible expansion of an ideal gas.

   2. Adiabatic expansion of an ideal gas through a throttling valve.

   3. Vaporization of liquid water at 80 °C and 1 bar pressure.

   4. Reaction between H2SO4 and NaOH in dilute aqueous solution at constant temperature and pressure.

Answer 1

Work is done for that

For isothermal reversible expansion ∆U and ∆H will be 0 as they both depend on temperature change and since temperature change is 0 they are 0 too . ∆S will not be 0 as pressure change will accompany.

For adiabatic expansion through throttling valve, when in throttling valve enthalpy is const hence ∆H is 0. ∆S will also be 0 as Q/T will be 0 as Jo heat goes out .

For vaporisation of water none will be 0 as it is no longer a ideal gas case it involves phanse change from liquid to vapor. Ofcourse ∆T is 0 but ∆V isn't.

In that reaction ∆S is not zero as when reaction happens disorderness will increase in the system as more products r formed hence not zero,also ∆U and ∆H will not be 0 as enthalpy of formation of products and reactants after addition isn't 0 means heat will releases or will be sucked during reaction hence both of those values not zero

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