These are summaries/practice questions the first 3 lectures from biochemistry, biomedical sciences year 1, at the VU.
How to learn:
- Use these questions as a guide for your lectures, if you want to read them.
- Practice daily with the questions. The questions summarize the study material and g...
1.0 THERMODYNAMICS
1.1 What is thermodynamics?
• Thermo = heat; dynamics = motion.
• A theory that links various forms of energy, and how their conversion can be used
to do work.
1.2 Explain the theorem of thermodynamics
The two laws of thermodynamics that you need to know are:
• energy is conserved.
• in a spontaneous reaction, the total entropy increases.
2.0 SYSTEM AND ENVIRONMENT
2.1 What is a system and what is an environment in thermodynamics?
Thermodynamics describes the exchange of energy between the system and its
environment.
• System: What you investigate. (anything)
• Environment: The rest. (universe)
3.0 VARIABLES
3.1 What are state variables?
• Independent variables that describe the state of the system at a given moment.
3.2 Are work and heat state variables?
• No because they depend on the process that led to the state.
3.3 What is the difference between intensive and extensive state
variables?
• Extensive variable: depends on system size
• Intensive variable: does not depend on system size
3.4 What variable tells us more about a system and how?
• Extensive variables do not help us determine the 'state' of the system. However,
intensive variables do. Temperature, density and pressure tell us a lot more about a system
than mass or volume (density can be calculated by mass or volume, so at the end they are
arguably as important -> a ratio of extensive variables give you an intensive variable!).
EX 3.5 = What variable is extensive and what is intensive?
• Volume - Number of molecules - Energy (why? Vragen) = Extensive
• Pressure - Concentration - Temperature = Intensive
,4.0 FIRST LAW OF THERMODYNAMICS
4.1 What is the first law of thermodynamics?
• Energy is conserved. It cannot be generated, nor disappear.
• It can only be converted.
4.2 What is the internal energy of a system?
• Internal energy is the sum of potential energy of the system and the system's
kinetic energy.
4.3 What can a system do with its internal energy?
• Do work: the energy content of the system decreases
• Produce heat: its energy content decreases
EX 4.4 = How does a system produce work by volume?
• System does work -> increases volume
• Internal energy decreases as a result
4.5 What is the formula of the first law?
• ∆U = q – W
• +q = heat goes into the system, U increases
• -q = heat goes out of the system, U decreases
• +W = system does work, U decreases
• -W = work is done on system, U increases
• W=p*∆V -> used in biochemistry!
5.0 ENTHALPY
5.1 What is enthalpy (dH; change)?
• Enthalpy (H) change is the heat added to or produced by the system at constant
pressure.
5.2 What is the formula of enthalpy?
• ∆H=∆U +p∆V
• ∆H is the heat added to or produced by the system at constant
pressure.
EX 5.3 If the volume changes are negligible, what can we assume in the
formula?
• ∆H ≈ ∆U.
6.0 Probability
6.1 What is probability?
• The drive/force that induces molecules/particles to spread in a homologues manner
across the surface they have (probability drive!)
, 6.2 What is multiplicity (W)?
• W is the number of microscopic arrangements that have the same macroscopic
appearance.
6.3 How do you calculate the probability with a known multiplicity?
• Pr(x) = P*W
EX 6.4 What does this graph suggest?
• It shows what will happen if the number of particles is increased
• It shows the following:
1. The chance for equal division (ratio of
0.5) increases.
2. The chance to find all particles together
decreases to nearly zero.
• Conclusion: the larger the systems, the less likely the un-even distribution
becomes!!
6.5 What is equilibrium?
• The most probable state. All particles are spread evenly. There is no driving force
anymore. There is no net exchange!
EX 6.6 What is happening here?
• Particles on the left move randomly in and out to right part.
• Due to probability drive, there will be net movement to the right.
• Equilibrium will take place.
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