CHEM20018 Thermodynamics Tutorial 2, 2025

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CHEM20018 Thermodynamics Tutorial 2, 2025

1.         Describe an acceptable working principle of Crookes’ radiometer.

2.         One mole of an ideal gas expands reversibly and isothermally from 10 atm to 1atm at 298 K.

Calculate:

a)     How much work is done on the gas as a result of its expansion.

b)     The amount of heat energy transferred to the gas.

c)     ΔU

d)     ΔH

e)     How much work is done on the gas if it expands from 10 atm to 1atm irreversibly against a constant external pressure of 1atm.

f)      ΔU if the reversible expansion is carried out adiabatically

3.         An aqueous solution ofunoxygenated haemoglobin containing 5 g of protein (M = 66,000 g

mol-1) in 100 cm3 of solution is placed in an insulated vessel.  When enough molecular oxygen is added to the solution to completely saturate the haemoglobin, the temperature is found to rise by 0.031° C.  Each mole of haemoglobin binds 4 mole of oxygen.

What is the enthalpy of reaction per mole of bound oxygen?  The heat capacity of water is 4.16 JK-1cm-3.

4.         One mole of an ideal gas expands from a volume of 1L to 10L at 298K.

State whether the values w, q, ΔU, ΔSsystem  and ΔSsurroundings  are >0, <0 or =0 in the following cases:

(a)     the expansion is reversible and isothermal

(b)    the gas expands freely

(c)     the expansion is reversible and adiabatic

5.         Calculate the final temperature (Tfinal), the work and the total entropy change (ΔtotalS) when two  metal blocks each of mass 1.00kg, one at 100.0oC and one at 10.0oC, are brought into contact in an isolated container. The specific heat capacity of the metal is 0.5 JK-1g-1 and may be assumed constant over the temperature range.

6.         Calculate the number of microstates available for two electrons within a set ofp orbitals.

Calculate the entropy of this system.