thermo master
1.
Q: What is the First Law of Thermodynamics?
A: Energy is conserved: \Delta U = q + w
2.
Q: What does q represent in thermodynamics?
A: Heat transferred into or out of a system.
3.
Q: What does w represent in thermodynamics?
A: Work done on or by the system.
4.
Q: What does \Delta U mean?
A: Change in internal energy of the system.
5.
Q: What is the formula for work by expansion/compression?
A: w = -P \Delta V
6.
Q: What is the equation for heat transfer without a phase change?
A: q = mc\Delta T
7.
Q: What is enthalpy (H)?
A: Heat content at constant pressure: H = U + PV
8.
Q: How is \Delta H calculated for a reaction?
A: \Delta H = \sum \Delta H_f^\circ(\text{products}) - \sum \Delta H_f^\circ(\text{reactants})
9.
Q: What is entropy (S) and its unit?
A: Measure of disorder; units = J/K or J/mol·K
10.
Q: How do you calculate \Delta S?
A: \Delta S = \sum S^\circ(\text{products}) - \sum S^\circ(\text{reactants})
11.
Q: What is the formula for Gibbs Free Energy?
A: \Delta G = \Delta H - T\Delta S
12.
Q: What does \Delta G < 0 mean?
A: The reaction is spontaneous.
13.
Q: What does \Delta G = 0 mean?
A: The system is at equilibrium.
14.
Q: How are \Delta G^\circ and K related?
A: \Delta G^\circ = -RT \ln K
15.
Q: What temperature unit must always be used in thermodynamics?
A: Kelvin (K)
16.
Q: What’s the formula for heat during a phase change?
A: q = n \Delta H_{phase}
17.
Q: What’s the difference between q in constant pressure vs. constant volume?
A: q_p = \Delta H; q_v = \Delta U
18.
Q: What’s the relationship between pressure-volume work and joules?
A: 1 \, \text{L·atm} = 101.3 \, \text{J}
19.
Q: What’s the equation for ideal gas law?
A: PV = nRT
20.
Q: What’s the equation relating K_p and K_c?
A: K_p = K_c(RT)^{\Delta n}
21.
Q: What constant is R in J/mol·K?
A: R = 8.314 \, \text{J/mol·K}
22.
Q: What constant is R in L·atm/mol·K?
A: R = 0.0821 \, \text{L·atm/mol·K}
23.
Q: What does a positive \Delta S mean?
A: More disorder or randomness in the system.
24.
Q: What is Hess’s Law?
A: The total enthalpy change is the sum of individual steps.
25.
Q: When is a phase change happening in a system?
A: When temperature remains constant while heat is added or removed.
26.
Q: What are standard \Delta H_{vap} and \Delta H_{fus} of water?
A: \Delta H_{vap} = 40.7 \, \text{kJ/mol}, \Delta H_{fus} = 6.01 \, \text{kJ/mol}
27.
Q: How do you determine spontaneity from signs of \Delta H and \Delta S?
A: Use the spontaneity table with \Delta G = \Delta H - T\Delta S
28.
Q: What is the unit of heat capacity?
A: J/g·K or J/mol·K
29.
Q: What is the sign of q if the system releases heat?
A: q < 0
30.
Q: What is the sign of w when the system expands against a piston?
A: w < 0