Question

6.Predict whether the values of q, w , U and H are positive, zero, or negative for each of the following processes:

Metling of ice at 1 atm and 273K

Melting of solid cylcohexane at 1 atm and the normal melting point

Reversible isothermal expansion of an ideal gas

Reversible adiabatic expansion of an ideal gas

For most substances, the volume increases upon melting, but for the ice melting to water under the given conditions, the volume decreases. In all cases the change in volume between solid and liquid phases is very small and work associated will be small also. For the ideal gas U and H depend on the temperature only

Answer 1

Answer:

1.

• To dissolve ice we should give warmth to it subsequently q will be certain(+).

• Volume of water diminishes on softening subsequently work done by the framework is negative.(or work done on the framework is certain).

• Despite the fact that volume change is little so you should expect it to be Zero. Inward vitality will increment as work and warmth is exchanged to the framework.

• Since procedure is endothermic(it requires heat) consequently change in H will be certain. (+)

2.

• Melting requires heat consequently q will be sure(positive).

• Volume will increment hencework done by the framework is certain ( or done on the framework negative). Inward vitality will expand (heat is given).

• Since procedure is endothermic H will increment or change is sure. (+)

3.

• In Isothermal extension of perfect gas heat is given for development henceforth q will be certain(+).

• Volume increments subsequently work done by the framework is sure(+) ( or work done the framework is negative). Inner vitality will stay same since Temperature remains same(Zero change) .

• Since dH = dU + d(PV)

since P1V1 = P2V2 and change in dU is Zero(0)

• Subsequently enthalpy will stay same (Zero change).