152 Chem A Winter 2008 Quiz 1
Name ___Answer Key________ Section ____________________ Score _________out of 10 pt
1 (3 pt) Calculate the work for the expansion of CO2 from V = 1.0 to 2.5 L against a constant pressure of P =1 atm (in units of L-atm) Constant external pressure w = -PV = -1.0 atm (2.5 L-1.0 L) = -1.5 L atm 2 (4 pt) Calculate E for a system that absorbs 85 J of heat while 47 J of work is done on the system:
E = q + w
= +85 J + 47 J = + 132 J
3 (3pt) Suppose you 45 add J of heat to a system, let it do 10 J of expansion work, then return the system to its initial state by cooling and compression. Which statement is true for this process? (Circle the TRUE statement) (a) H < E (b) The work done in compressing the system must exactly equal the work done by the system in the expansion step. (c) H = 70 J (d) The change in the internal energy E for this process is zero. _______________________________________________________________