for the following processes, state whether each of the thermodynamics quantities, q, w, delta U, and delta H is greater than, equal to, or less than zero for the system described. Explain your answers briefly
a) an ideal gas expands adiabaticalally against an external pressure of 1 bar.
b) an ideal gas expands isothermally against an external pressure of 1 bar
c) an ideal gas expands adiabatically into a vacuum
d) a liquid at its boiling point is converted reversibly into its vapor, at constant temperature and 1 bar pressure
e)H2 gas and O2 gas react in closed bomb at 25 degree Celsius, and the product water is brought back to 25 degree Celsius
For ?H=?U+P?V as P?V = w therefore ?H = ?U+w
From the above we know that in this case ?U = -w
Therefore, ?H=-w+w =0
The pressure of 1bar is nearly equal to 1atm which is the standard pressure.
For ?H=?U+P?V as ?U =0 therefore, ?H = +w. So, ?H has value greater than zero.
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