# Search results

1. ### Gibbs' theorem and partial molar volume

In the chemical engineering text of Smith, VanNess, and Abbott, there is a section on partial molar volume. It states that Gibbs theorem applies to any partial molar property with the exception of volume. Why is volume different? In other words, when evaluating the partial molar volume of a...
2. ### Analysis of tennis string tension

I have a decent background in physics, but something that has always confused me is how to think about how the tension of the string in a tennis racquet affects how the ball leaves the strings. For example, the traditional lore in tennis is that tauter strings will give more control, whereas...
3. ### Why does Planck's BB emissive power increase with n?

This question is regarding the dependence of Planck's law for black-body (BB) radiation intensity (or integrating over a hemisphere, the emissive power, E = pi * I). Physically speaking, why is it that a BB emitting in a medium with n>1 (n being index of refraction) emits a higher power/area...
4. ### 1st law: Thermo equation 6.1 from Smith, Van Ness, Abbott

On page 200 in the 7th edition of Intro to ChemE Thermodynamics by Smith, Van Ness, and Abbott, there is an equation that has always bugged me since reading it (or rather the interpretation of it, not the derivation). It is equation 6.1 and states: d(nU) = T d(nS) - P d(nV) with n = moles in the...
5. ### Why do phase trxns behave differently than chemical rxns?

If we have solid water (ice) at -5 C and atm P, then according to thermodynamics, the process that takes that ice (at -5 C & atm P) from solid to liquid is non-spontaneous, which means its ΔG > 0. Hence, it is impossible for someone to observe ice melt to liquid at -5 C, and assuming we started...
6. ### Where does band index come from in block wave functions?

Can you show me as explicitly as possible through equations?
7. ### Show that the Slater Determinant states are a complete basis

Homework Statement "Show that the Slater Determinant states are a complete basis" is the entire statement. Homework Equations The Attempt at a Solution I guess I'm trying to prove that the rank of the states is equal to the basis? I'm not sure where to start on this one.
8. ### Question from Ashcroft/Mermin: electronic density eqn

I'm taking a SS physics course and going through A&M and found something hard for me to understand. It is on page 44, starting with eqn 2.60. Another thread almost addressed my question, but I cannot post replies on the thread (click here). I think I understand what is going on in the 1st...
9. ### QM questions: MO theory orbital combination

1) When we learn about MO theory, we learn that there are different ways to combine atomic orbitals to find the molecular orbitals for a molecule. However, going back to the fundamental/physical meaning of orbitals, orbitals are the wavefunctions. Wavefunctions do not have any physical meaning...