Wednesday, February 9, 2011

Noting Wednesday

Hello 6th period friends!

In case you didn't know, we did notes all day today. We learned a lot more about light energy and wavelengths. First, we learned that wavelengths and frequency are indirectly related, so the longer the wavelength, the lower the frequency, and the shorter the wavelength, the higher the frequency. We can use the equation λv=c, where λ is in meters/wave, v is in # of waves/second, and c is the speed of light, which is 3x10^8.

Next, we learned about the electromagnetic spectrum which looks like this:



This gives you a nice visual and adds how long each wave is, so that's helpful. We can only see a very small sliver of the spectrum, specifically the rainbow. This is the area that says "visible" in the picture.

After that, we learned about two very interesting scientists who had opposing ideas about where light came from. Max Planck explained that the transfer of energy was not continuous, and that the energy was quantized, like rungs on a ladder. He believed that light came in waves and believed that it could be explained through his formula ΔE=hv where ΔE is the change in energy, h is Plank's constant 6.626x10^-34, and v is velocity.

On the other hand, Albert Einstein believed that radian was made up of a stream of partciles called photons. He did agree that the energy was quantized, though.

Solving the mystery was Louis de Broglie, who applied the wave-particle theory to electrons. There was a "dual nature of light". His equation is λ=h/mv, where λ is the wavelength, h is Planck's constant, m is the intial mass, and v is velocity.

Remember that the energy in a wavelength is QUANTIZED and has to be a whole number!

During this part of the class, Liebs gave us some really cool psychedlic glasses that allowed us to see the light coming off a helium light bulb. This is something like what we saw when we put them on.





We then went on to learn that when an electron has a very high energy drop, this is what causes it to have a high frequency. Liebs demonstrated this by getting up onto the table and then jumping back down. Also, if an electron has a low energy drop, it has a low frequency. This happens at the speed of light and is impossible to see with the naked eye.

Then we learned something truly astonishing. Niels. Bohr. Was. Wrong.

According to Bohr's model of the atom, the electrons moved in orbits around the nucleus, staying on a similar course the entire time. But, if this was true, a loss of energy would cause the electron to spirial toward the nucleus and crash into it. Obviously, this does not happen, as Ben T. pointed out because otherwise, we would be blowing up all the time.

Instead, electrons move in orbitals. They are different from orbits, as each electron moves around in its own cloud. The atom is mostly empty space except for the nucleus and the regions were you would find an electron. The probability of predicting where the electron is is very possible, but no one can predict it exactly accurately, because they are just regions of space. There is about a 90% probabilty of finding an electron, for it is very vague.



That was about all we did today. I would post the notes, but they aren't on slideshare :( But this is about all we did. Also, the first question on the worksheet we got today is for homework, get it here!

Have a nice Wednesday!

The next scribe will be.........Matteo Parque, enjoy!

:)

Wednesday, February 2, 2011

test

the test will be monday

Entropy and Gibbs free energy

GIBBS FREE ENERGY

Defined: the energy in the system that is available to do useful work.

It is given this symbol eq=\Delta G and can be calculated like this eq=\Delta G = G(products)- G(reactants)

Remember that Gibbs free energy is measured in Kj/Mol

THINGS YOU SHOULD KNOW

  1. If eq=\Delta G is negative the forward reaction is spontaneous
  • If eq=\Delta G is negative then A+b ------> C would be spontaneous
2. If eq=\Delta G is positive then the opposite is true
THE MOST COMMON WAY TO CALCULATE eq=\Delta G IS
eq=\Delta G=eq=\Delta Heq=- T \Delta S
this table gives you a feel of what happens with Gibbs free energy but CHECK YOUR BOOK FOR THE OTHER ONE THAT GOES INTO MORE DETAIL.


Δ G

Reaction Behavior

Negative

Proceeds spontaneously to the right

Zero

Is at equilibrium

Positive

Will not proceed


That was about it for today. Remember we got another worksheet that will be due on test day which is now Friday because of the snow day.

Below is the entropy post

ENTROPY SHENANIGANS

We started off class today with lab review I am going to type on of the reactions that we reviewed and if you have any questions about the second two reactions, post a comment and I, or someone else, will do their best to answer.

REACTION ONE

Mg + 2HCl ------> MgCl2 + H2 eq=\Delta Rxn= \frac{KJ}{Mol}

You can use q=mc eq=\Delta T

BUT WAIT HOW DO YOU GET THE MASS!!!!

Though only the people who got the Mg would know you use a simple conversion factor ofeq=\o Mg = CmMg * \frac{.01085}{1cm}

After that you would find the moles of magnesium by these equation

eq=\o Mg = CmMg * \frac{.01085}{1cm} * \frac{1\o}{b24g}

REMEMBER – this was done twice – you need to do the process above two times and then calculate the average. THIS GOES FOR ALL THREE REACTIONS DON’T FORGET THIS THE MORE ACCURATE YOU ARE THE LOWER YOUR PERCENT ERROR WILL BE

Once you have all three of the equations done you need to use Hess’s law AND SHOW YOUR WORK. This work should be shown in the evidence section that lap

CHEM NOTES

Seeing As the slide share link always takes me to gun manuals I am going to type out my notes.

  1. We started with spontaneous reactions
  2. A SPONTANEOUS REACTION IS A REACTION THAT TAKES PLACE ON ITS OWN WITHOUT OUTSIDE FORCES
    1. there are a few things to be worried about though, LIKE

i. It does not have to start on its own so long as it carries out the rest of the experiment

ii. If it spontaneous in one direction then it is not spontaneous in the other direction

  1. Examples of spontaneous reactions
    1. Hydrogen ballon reaction
    2. Paint can explosion
    3. Ice cube melting
    4. RUBBER BAND

i. This was the one we spent the most time on

1. The reason that it is such a good example was because when a rubber band is left to sit, it is going to sit there and not move. No matter how much you want something to happen without touching the rubber band, it wont happen. However if stretched out and then contracted, that contraction is a spontaneous reaction because it goes from being stretched out to a normal state with no outside influence

ii. You should not that spontaneous reactions have nothing to do with speed. Below is a great picture for the visual learners out there. if it doesn't show up the it is also here

iii.

    1. Nature allows spontaneous reactions

i. Nature divides spontaneous reactions in two main ways

1. Maximum probability – this is where everything mixes

2. Minimum probability – nature has the chance to become disordered but does not

  1. ENTROPY
    1. Entropy is denoted with “S”
    2. Defined as – the increase in disorder or randomness
    3. REMEMBER TO USE j/mol K NOT Kj/mol K

i. Nature always wants to move toward a positive entropy

    1. MICROSTATES: different ways molecules can be distributed

i. Increase of microstates = an increase of entropy

ii. large number of microstates = large probability of different states = higher entropy

    1. FACTORS THAT INFLUENCE ENTROPY

i. Liquid has a great entropy than solid

ii. Gas has the highest

    1. CALCULATING ENTROPY

i. Very similar to calculating enthalpy

1. It is eq=\Delta S =\Sigma S(products)-\Sigma S reactants

2. REMEMBER COEFFICIENTS ARE USED IN THE EXACT SAME WAY WHEN CALCULATING ENTROPY AS THEY ARE WHEN YOU ARE CALCULATING ENTHALPY

a. If there are 2mol of something you multiple by 2 etc

http://www.youtube.com/watch?v=B4SFv_2Skdc&feature=related

This video does a good job summarizing the lesson today.

Alright well I am about done there are just a few announcements you should be aware of

  1. Today is Kathryn J’s birthday if you haven’t wished her a happy birthday DO IT
  2. Mr. Lieberman has his ear pierced, though he never wears it
  3. The lab is due tomorrow
  4. There is a web assign due Wednesday
  5. The class would like to congratulate Mollie and Emilio for… Well, being Mollie and Emilio ;)
  6. We got a Worksheet today that you should do
  7. Everything for this chapter including both sets of book problems will be due on Thursday and if we have a snow day on Wednesday well then I am not sure.

That’s about it for today. The next scribe is Kathryn J, enjoy

Tuesday, February 1, 2011

units for entropy

I misspoke in class the other day. The correct units for entropy are (j/mole K). That means that you have to put your entropic values in Kilojoules in order to use them in the gibbs free energy formula!!! Plz pass this on

Monday, January 31, 2011

Entropy

***NOTE*** this is Bobby Shaw's post, he just didn't have access to our blog so I'm posting it for him.


We started off class today with lab review I am going to type on of the reactions that we reviewed and if you have any questions about the second two reactions, post a comment and I, or someone else, will do their best to answer.

REACTION ONE
Mg + 2HCl ------> MgCl2 + H2
You can use q=mc
BUT WAIT HOW DO YOU GET THE MASS!!!!
Though only the people who got the Mg would know you use a simple conversion factor of
After that you would find the moles of magnesium by these equation

REMEMBER – this was done twice – you need to do the process above two times and then calculate the average. THIS GOES FOR ALL THREE REACTIONS DON’T FORGET THIS THE MORE ACCURATE YOU ARE THE LOWER YOUR PERCENT ERROR WILL BE

Once you have all three of the equations done you need to use Hess’s law AND SHOW YOUR WORK. This work should be shown in the evidence section that lap


CHEM NOTES

Seeing As the slide share link always takes me to gun manuals I am going to type out my notes.

1. We started with spontaneous reactions
2. A SPONTANEOUS REACTION IS A REACTION THAT TAKES PLACE ON ITS OWN WITHOUT OUTSIDE FORCES
a. there are a few things to be worried about though, LIKE
i. It does not have to start on its own so long as it carries out the rest of the experiment
ii. If it spontaneous in one direction then it is not spontaneous in the other direction
3. Examples of spontaneous reactions
a. Hydrogen ballon reaction
b. Paint can explosion
c. Ice cube melting
d. RUBBER BAND
i. This was the one we spent the most time on
1. The reason that it is such a good example was because when a rubber band is left to sit, it is going to sit there and not move. No matter how much you want something to happen without touching the rubber band, it wont happen. However if stretched out and then contracted, that contraction is a spontaneous reaction because it goes from being stretched out to a normal state with no outside influence
ii. You should not that spontaneous reactions have nothing to do with speed.
iii.
e. Nature allows spontaneous reactions
i. Nature divides spontaneous reactions in two main ways
1. Maximum probability – this is where everything mixes
2. Minimum probability – nature has the chance to become disordered but does not
4. ENTROPY
a. Entropy is denoted with “S”
b. Defined as – the increase in disorder or randomness
i. Nature always wants to move toward a positive entropy
c. MICROSTATES: different ways molecules can be distributed
i. Increase of microstates = an increase of entropy
ii. large number of microstates = large probability of different states = higher entropy
d. FACTORS THAT INFLUENCE ENTROPY
i. Liquid has a great entropy than solid
ii. Gas has the highest
e. CALCULATING ENTROPY
i. Very similar to calculating enthalpy
1. It is
2. REMEMBER COEFFICIENTS ARE USED IN THE EXACT SAME WAY WHEN CALCULATING ENTROPY AS THEY ARE WHEN YOU ARE CALCULATING ENTHALPY
a. If there are 2mol of something you multiple by 2 etc

d


This video does a good job summarizing the lesson today.

Alright well I am about done there are just a few announcements you should be aware of

1. Today is Kathryn J’s birthday if you haven’t wished her a happy birthday DO IT
2. Mr. Lieberman has his ear pierced, though he never wears it
3. The lab is due tomorrow
4. There is a web assign due Wednesday
5. The class would like to congratulate Mollie and Emilio for… Well, being Mollie and Emilio ;)
6. We got a Worksheet today that you should do
7. Everything for this chapter including both sets of book problems will be due on Thursday and if we have a snow day on Wednesday well then I am not sure.
That’s about it for today. The next scribe is Ben T, enjoy