Physical 1 Topic 5

Thermodynamics V

Gases … to fill the total volume: the driving force is …

expand, entropy

What is the equation linking entropy change to change in volume?

dS = nRln(V₂/V₁)

n = mol

R = 8.314 J K^-1 mol^-1

Change in entropy is dependent on the … of the system

temperature

Entropy … with increasing temperature

increases

How the entropy changes with temperature depends on the … of the system

heat capacity

What is the equation linking heat capacity with temperature change?

C = q/dT

q = J

dT = K

What does the heat capacity determine?

the amount by which the temperature of a substance rises when heated

What is the equation linking change in entropy and heat capacity?

dS = C_V/pln(T₂/T₁)

dS = J K^-1

C_V or C_p = J K^-1

What must be done before temperatures can be substituted into the equation and why?

convert to Kelvin: units of temperature do not cancel like m³ etc. does

When two systems at different … come into contact, energy will flow as … from the … system to the other

temperatures, heat, hotter

The decrease in entropy of the … system is smaller than the increase in entropy of the … system because entropy is dependent on …

hotter, colder, temperature

Entropy is a … function, so the overall change can be broken into … changes

state, component

What is the equation linking change in entropy and volume at a constant temperature?

dS = nRln(V₂/V₁)

n = mol

R = 8.314 J K^-1

Third Law of Thermodynamics:

The entropy of a perfectly crystalline substance at zero Kelvin is zero

Kirchoff’s Law:

dH = C_p(T₂ - T₁)

Heat capacity is a …

state function

The change in heat capacity for a reaction is given by …

taking the difference between the stoichiometrically weighted sums of the products and reactants

dG =

VdP - SdT

What is the equation linking change in Gibbs free energy and pressures?

dG = nRTln(P₂/P₁)

What is the equation linking change in Gibbs free energy and volumes?

dG = nRTln(V₁/V₂)

What is the equation linking initial and final pressures and volumes?

P₁V₁ = P₂V₂