Thermochemistry Flashcards
1
Q
Equation for work (w) required for the compression of an ideal gas.
A
w = - PΔV, where p = pressure and ΔV = change in volume
2
Q
1st Law of Thermodynamics
A
The internal energy of a system is the sum of heat absorbed (q) and the work (w) done by the system. ΔU = w + q
3
Q
2nd Law of Thermodynamics
A
For any process to occur spontaneously, entropy must increase. ΔS > 0 (positive change in entropy)
4
Q
General trends of entropy
A
- Entropy increases when temperature increases.
- Entropy increases when molecules go from dense states (solids and liquids) to gas state
- Entropy decreases when an ideal gas is compressed
- Entropy is 0 when a material is at absolute zero
5
Q
3rd law of thermodynamics
A
A material at absolute zero will have an entropy of zero.
6
Q
Explain the concept of work (w)
A
Work is the energy done BY, or done TO a system, independent of heat (q). The change in internal energy (ΔU) therefore = w + q
