Physical chemistry for food scientists
Lecture 1
Types of systems:
- Open system (mass and energy exchange)
- Closed system (energy exchange but no mass exchange)
- Isolated system (no mass exchange and no energy exchange)
Types of processes:
- Isothermal (constant temperature)
- Isobaric (constant pressure)
- Isochoric (constant volume)
Volume = V = m3
Molar volume = v = m3/mol
Intensive variables – do not change when the size of the system changes (e.g. p, T)
Extensive variables – do change when the size of the system changes (e.g. V, n, U)
State variable – thermodynamic variable with specific value in every thermodynamic state of system (e.g. p, T, V,
n, U) (bijv. afstand hemelsbreed)
Not state variable – thermodynamic variable that depends on process (e.g. Q, W) (bijv. afgelegde afstand)
! To distinguish between pure components and components that are mixtures, we add an asterisk * to the pure
component.
Four basic laws of thermodynamics:
0th law – If two bodies are each in thermal equilibrium with a third body, it follows that the first two bodies are in
thermal equilibrium with each other
1st law – Energy is conserved (energy can be transformed from one form into another, but the total energy is
constant; energy is never created or destroyed)
2nd law – Heat always flows from a hot to a cold body
3rd law – Absolute zero temperature (K=0) can never be reached
Ideal gas law – pV = nTR
p = pressure, V = volume, n = number of moles, T = temperature, R = gas constant (8,314)
The ideal gas law is only valid when the atoms are very small and have no interaction with each other
v = V/n (pV = nTR becomes pv = RT)
Lecture 2
Coexistence curves = phase boundaries – the solid lines that separate the different regions in the phase diagram
(boiling curve, melting curve & sublimation curve)
Latent heat – the heat that is necessary to induce the phase transition
Lecture 1
Types of systems:
- Open system (mass and energy exchange)
- Closed system (energy exchange but no mass exchange)
- Isolated system (no mass exchange and no energy exchange)
Types of processes:
- Isothermal (constant temperature)
- Isobaric (constant pressure)
- Isochoric (constant volume)
Volume = V = m3
Molar volume = v = m3/mol
Intensive variables – do not change when the size of the system changes (e.g. p, T)
Extensive variables – do change when the size of the system changes (e.g. V, n, U)
State variable – thermodynamic variable with specific value in every thermodynamic state of system (e.g. p, T, V,
n, U) (bijv. afstand hemelsbreed)
Not state variable – thermodynamic variable that depends on process (e.g. Q, W) (bijv. afgelegde afstand)
! To distinguish between pure components and components that are mixtures, we add an asterisk * to the pure
component.
Four basic laws of thermodynamics:
0th law – If two bodies are each in thermal equilibrium with a third body, it follows that the first two bodies are in
thermal equilibrium with each other
1st law – Energy is conserved (energy can be transformed from one form into another, but the total energy is
constant; energy is never created or destroyed)
2nd law – Heat always flows from a hot to a cold body
3rd law – Absolute zero temperature (K=0) can never be reached
Ideal gas law – pV = nTR
p = pressure, V = volume, n = number of moles, T = temperature, R = gas constant (8,314)
The ideal gas law is only valid when the atoms are very small and have no interaction with each other
v = V/n (pV = nTR becomes pv = RT)
Lecture 2
Coexistence curves = phase boundaries – the solid lines that separate the different regions in the phase diagram
(boiling curve, melting curve & sublimation curve)
Latent heat – the heat that is necessary to induce the phase transition
