Workshop Last Week

I should have probably done this before the exam last week, but maybe this will help someone for the final.

So, last week's workshop was all about orbitals in atoms with more than one electron. Here are the main points:

• Sub-orbitals (s,p,d,f) only differ in energy in atoms with more than one electron. When the sub-orbitals in an orbital (n=1,2,3...) all have the same energy, the atom is called degenerate.
  
• s, p, d, and f is the ording of sub-orbitals from lowest to highest energy.
• Only one emission line is observed on a spectrum of a degenarate atom (like hydrogen) when its electrons jump one energy levels. In non-degenarate atoms, mutiple lines are observed because of the fact that sub-levels (l) must change by + or - in the transition of an electron.
  
• Shielding refers to the fact that the core electrons in mutiple-electron atoms shield the atom's valence electrons from the full nuclear charge. Shielding is what makes multiple-electron atoms not degenerate.
• Periodic trends: ionization energy increases from left to right across a period and decreases top to bottom down a group. The opposite is true for atomic radius.
  

Thats it!

Exam Question Workshop 8

A common thing for teens in Rural WNY to do on dull midsummer days is to blow 2L bottles up. They do this in a non-neferious kind of way, in their open fields. They take a soda bottle and fill it with The Works Toilet Bowl Cleaner, then add balls of Aluminum Foil, cap it off, shake it and run. This reaction can easily explode large pumpkins and has the equation:

NaOH + Al --> Al(OH)3 + Na2O + H2

This reaction is performed at 24C and through your laboratory experiment the Activation Energy was determined to be 48kJ/mol. If these teens wanted to carry this reaction out at 8 times the rate, what would the Temperature have to be?

Figuring out E* at different pH's of water

There was one exam problem in which it asked you to calculate the E* of 2H+ + 2e- --> H20 at pH of 5. Will this type of problem be on the test, and if so what is the basic way to solve this problem.

Workshop post

sorry for the late post but here it is:

Oxidizing agent is in Cathode. Reducing agent is in Anode.

Negative ions (such as NO3-) leave salt bridge to the ANODE to prevent build up of positive charge (which would stop the system)

Positive ions (such as K+) leave salt bridge to the Cathode to prevent build up of negative charge (which would stop the system)

Electrons flow from anode to cathode.

finally (i know its been saiid but its important): REDUCTION POTENTIAL IS THE ABILITY OF SOMETHING TO BE REDUCED!!!!!!!!! HIGHER REDUCTION POTENTIAL WILL OXIDIZE ANYTHING WITH A LOWER REDUCTION POTENTIAL. IT IS A REALLY GOOD OXIDIZING AGENT. (and vice versa for a high oxidation potential).

Workshop 5 notes!

oxidizing agent- is being reduced, looses electrons + charge
reducing agent- gets oxidized, gains electrons - charge

If reduction potential is high, there is a higher potential to get reduced. They are also good oxidizing agents

If reduction potential is low, it will reduce anything and it will get oxidized

Ecell= Ecathode - Eanode

Chemistry Chapter 10 exam question

For ammonia (NH3) the enthalpy of fusion is 5.65 kJ/mol and the entropy of fusion is 28.9 j/kmol.
a. will the NH3 spontaneously melt at 200 K?
b. What is the approximate melting point of ammonia?


Question 47 from chapter 10.

Workshop #3 Fun

Ok, so here’s some fun information we learned today:

*Equations
∆S_universe = ∆S_system + ∆S_surroundings

a) Reversible:
∆S = q_rev/t_f = (nC∆T)/t_f

b) Irreversible:
∆S = n C ln(T_f/T_i) = n R ln(V_f/V_i)

*For entropy changes: (like in the exploration in the workshop)
If the surroundings don't really change temperature, the process will be reversible. (exp. a(I))
If the surroundings do change temperature noticeably, the process will be irreversible. (a(II))
The same goes for the system. (the iron piece)
(The wonderful example of the millionaire vs. the college student with $50)

*Entropy is independent of path of process
There will be the same amount of entropy transferred if it goes back and forth randomly before it reaches the final, or if it goes directly to the final entropy.
(It doesn't matter how you get to the final point, just as long as you get there.)