1. For each of the following processes, deduce whether the quantities q, w, AU,
ID: 1089592 • Letter: 1
Question
1. For each of the following processes, deduce whether the quantities q, w, AU, AH, AS, and AS(total) are positive, zero, or negative. MAKE A TABLE: you can label the processes in the first column by the letters a) through g). No explanations are requested, but you will learn A LOT by thinking these through. a) reversible melting of ice at 1 atm and 0 °C. b) reversible boiling of water at 1 atm and 100 °C. c) reversible adiabatic expansion of an ideal gas d) reversible isothermal compression of an ideal gas e) reversible heating of an ideal gas at constant P f) adiabatic expansion of an ideal gas into vacuum (not reversible) g) adiabatic expansion of a gas with only attractive forces into vacuum (not reversible)Explanation / Answer
a)
q -->positive, heat is added
w --> almost zero, no change in volume (considereably)
dU = --> increases since liquid > solid in intermolecular forces
dH = --> increases since liquid > solid in intermolecular forces
dSsystem --> increases since liquid has more chaos than solid
dStotal --> since reversible = 0
b)
q -->positive, heat is added
w --> positive since the change in volume is veyr high considereably
dU = --> increases since gas > liquid in intermolecular forces
dH = --> increases since gas > liquid in intermolecular forces
dSsystem --> increases since gas has more chaos than liquid
dStotal --> since reversible = 0
c)
q -->negative, heat is lost
w --> positive since the change in volume, and it expands
dU = --> decrease since expansion implies decrease in T
dH = --> decrease since expansion implies decrease in T
dSsystem --> increases since more chaos
dStotal --> since reversible = 0
d)
q --> Heat is lost by system
w --> Work must be negtive, since changes in volume
dU = --> 0, since no change in T
dH = --> 0, since no change in T
dSsystem --> Decreases, since it is acompression, the system gest ordered
dStotal --> since reversible = 0
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