In: Chemistry
1. For each process, predict the sign of U, q, and w:
a. An ideal gas expanding in the vacuum of outer space
b. A real (not-ideal) gas expanding in the vacuum of outer space
c. A read (not-ideal) gas expanding in our atmosphere
d. A muscle cell using anaerobic oxidation to bench-press 200 lbs.
e. Nitromethane combustion being used to power a top-fuel dragster.
f. External voltage being used to charge a lithium battery (which is an endothermic reaction).
1.a. this is an irreverisble and isothermal free expansion process.
so, U = f(T), therefore, , and it is free expansion, so work done (w) = 0 and from first law of thermodynammics q =0
1.b. this is also an irreverisble isothermal free expansion process.
so, U = f(T), therefore, , and it is free expansion, so work done (w) = 0 and from first law of thermodynammics q =0
1.c. this is irreversible expansion. here, work will done by the system, therefore w = -ve (negative) [ -w = p(V2-V1) and V2> V1, where V is the volume]. system will absorb heat to do the work, q = + ve. therefore, sign of will be = +ve