CHEM122 Thermodynamics

What is the first law of thermodynamics?

Energy cannot be created or destroyed, only transformed.

What does the second law of thermodynamics state about entropy?

Entropy is always increasing in an isolated system, indicating energy transformations are not 100% efficient.

What happens to the entropy of a perfect crystal as temperature approaches absolute zero according to the third law of thermodynamics?

The entropy approaches zero.

What is enthalpy in thermodynamics?

Enthalpy (H) is defined as H = E + PV, useful for processes at constant pressure.

What is the relationship expressed in the first law of thermodynamics?

The change in internal energy (ΔE) is equal to the heat added to the system (q) plus the work done on the system (w): ΔE = q + w.

How is work (w) defined in thermodynamics?

Work is defined as the product of pressure (P) and change in volume (ΔV), expressed as w = -P × ΔV.

What do exothermic reactions do in terms of heat?

Exothermic reactions release heat (ΔH_r < 0).

What does Hess's Law state?

The total enthalpy change for a reaction is the same regardless of the number of steps taken.

What does entropy measure in thermodynamics?

Entropy measures disorder or randomness in a system.

What is Gibbs Free Energy (G)?

Gibbs Free Energy is defined as G = H - TS, indicating the maximum reversible work obtainable from a thermodynamic system at constant temperature and pressure.

How is spontaneous process characterized in terms of entropy?

A spontaneous process is characterized by an increase in the entropy of the universe.

What is the significance of the standard enthalpy of formation (ΔH°_f)?

It's the change in enthalpy when forming one mole of a compound from its elements in standard states, with ΔH°_f = 0 for elements in their most stable form.

What is the formula that relates Gibbs Free Energy to the reaction quotient Q?

ΔG = ΔG° + RTln(Q).

What is the probability using binomial distribution for four molecules being in the left flask?

0 in left flask: 0.0625, 1 in left flask: 0.2500, 2 in left flask: 0.3750.

What happens to entropy when heat transfers from a hot body to a cold body?

The entropy of the cold body increases.

What occurs during isothermal processes in ideal gases?

The internal energy remains unchanged, and q = -w.

What defines a reversible process in thermodynamics?

A reversible process allows both the system and surroundings to return to their original conditions, achieving maximum efficiency.

What does ΔS ≈ q/T imply about entropy changes?

The change in entropy is proportional to the heat transferred divided by the temperature at which the transfer occurs.

What is enthalpy change for a reaction expressed as?

ΔH_r = H_products - H_reactants.