CHEMISTRY COMMUNITY

Matthew 1C

I think that's pretty much what we should know since there wasn't much covered in lecture about it other than that

Matthew 1C

yeah I think the only difference is adding OH- to balance the H+. Then the OH- and H+ ions on the same side can be added to form H₂O

Matthew 1C

Joyce Gu 1E wrote:where can i find this practice final?

search red panda and you'll find it!

Matthew 1C

adiabatic means there is no heat transfer and isothermal means that the temperature stays constant

Matthew 1C

with 1st order reactions there is only one reactant but for 2nd order reactions there can be two first order reactants but I think most of the time we will use reactions with one 2nd order reactant because that uses the 2nd order integrated rate law found on the formula sheet of the test

Matthew 1C

for part a) since catalysts speed up the rate of a reaction the rate law would be affected in that the value of the rate would be larger than the rate of the reaction without the presence of a catalyst. for part b) the lowered activation energy means that the constant is greatly increased, which is ...

Matthew 1C

the collision theory says that gas molecules only react if they collide with enough kinetic energy, and the transition state theory says that the reactants form an activated complex, which is also known as a transition state

Matthew 1C

a pot without a lid on a stove is an example of a common open system, while a pot with a lid is an example of a closed system. an isolated system could be something like a thermos

Matthew 1C

I'm not sure if this answers your question, but one advantage of using heterogenous catalysts is that you can easily recover the catalyst for reuse whereas homogenous catalysts mix with the reaction so you can't really recover it

Matthew 1C

In regards to the graphs, how do you know what the y intercepts are?

Matthew 1C

Keliana Hui 2E wrote:What does order of reactants mean?

The order of the reactant is the value of n, which is the exponent of the concentration of the reactant in the rate law

Matthew 1C

The book also states that increasing the concentration of a species with a negative order would slow down the reaction because it participates in a reverse reaction

Matthew 1C

What would an order that's a fraction mean?

Matthew 1C

I think the only difference is having to add OH- to each side to balance the H+. Then the OH- and H+ on one side of the reaction can be added to form water and then cancel out the common terms on each side

Matthew 1C

how does one go about writing out a cell diagram?

Matthew 1C

Yep it's just electrochemistry. The class website says it'll cover chapter 14.1-14.11

Matthew 1C

The second law of thermodynamics states that in an isolated system, entropy is always increasing and the system degenerates into a more disordered state

Matthew 1C

Degeneracy is the number of ways of chivying a given energy state, and degeneracy's relation to entropy is found in the Boltzmann equation of S=k_blnW, in which the number of microstates, or degeneracy, is W

Matthew 1C

to convert to the gas phase you use the enthalpy of sublimation or vaporization and take those values into account when calculating the total enthalpy

Matthew 1C

also, degeneracy is taken into account when computing the actual value of entropy. their relationship between each other is seen in the Boltzmann equation

Matthew 1C

I think the reason P₁/P₂ is used is because it is inversely proportional to volume, which uses V₂/V₁. Also since both pressure and volume are directly proportional to temperature, does it matter which one uses 1/2 or 2/1?

Matthew 1C

Also, degeneracy is the value W in the Boltzmann equation, which is S=K_blnW

Matthew 1C

in class it was said that the third law of thermodynamics says that the limit of S as the temperature approaches 0 Kelvin equals 0. What that says is that the entropy at 0 Kelvin is 0, so it is perfectly ordered material

Matthew 1C

In friday's lecture, Dr. Lavelle's powerpoint said "if a system can be prepared in only one way, then S=KblnW=0". What did he mean by prepared in only one way? I'm not completely sure what he meant by this line and how it relates to the equation. When it says something can only be prepare...

Matthew 1C

Why is entropy at its maximum at equilibrium?

Matthew 1C

I don't know if any specific homework problems will be covered on the test, so I think it's more important to understand concepts and equations that we covered in class, such as enthalpy and work, and be able to apply them to whatever questions are asked

Matthew 1C

While the argument can be made that the universe can technically be considered a perfectly isolated system, fully isolated systems that are confined to our world are rare

Matthew 1C

Yes because it can equilibriate with the pressure of the surroundings

Matthew 1C

Internal energy is the energy stored in the system as kinetic and potential energy. Enthalpy is calculated with the internal energy, which is the energy required to make the system, along with the energy required to make room for the system, the product of the pressure and volume.

Matthew 1C

Steam burns a lot more than boiling water because more energy is required for phase changes than just temperature changes. With boiling water, the energy that is transferred to the skin will come from the temperature change, but with the steam, a lot of energy will be released onto the skin from the...

Matthew 1C

In constant volume the system doesn't expand, so the heat added will only go towards increasing temperature. However, expansion can occur at constant pressure, and some of the heat added will be spent on that expansion, along with increasing temperature. Since some of the heat will be spent in expan...

Matthew 1C

Which coordination compounds are the most prominent in regards to their biological importance? Which should we be able to identify and understand?

Matthew 1C

since the value of c is constant, being the speed of light, you can use the equation to solve for either wavelength of frequency, depending on what the given values are

Matthew 1C

will we be asked to identify which molecule is a bronsted acid/base or Lewis acid/base like in your example above on the final?

Matthew 1C

Are we expected to know examples of them or is it sufficient enough to understand what they are/what they can do?

Matthew 1C

https://upload.wikimedia.org/wikipedia/ ... onding.png

idk if this helps but it shows how there can be more than just one pi bond. it also shows how a sigma bond forms in comparison to pi bonds

Matthew 1C

Iron is used when the compound is positively charged, and ferrate is used when the compound is negatively charged.

Matthew 1C

I know you can have multiple pi bonds, but can you have multiple sigma bonds? In all of our examples it seems that there is only ever one sigma bond. You can have multiple sigma bonds if you're counting bonds in a molecule, say for example a molecule has a single bond and a double bond, then there ...

Matthew 1C

And while you know that the angles will be either slightly larger or slightly smaller, I think the only way to find out the exact angle is to look it up

Matthew 1C

Since all bonds are treated as equivalent in the VSEPR model, it doesn't matter which resonance structure is used

Matthew 1C

Since it needs to have the same nuimber of valence electrons, something isoelectronic with F- would have 10 valence electrons and have the same electron configuration of Ne, such as Na+ or O2-

Matthew 1C

so does that mean in order to find the most stable structure it's kind of a trial and error type thing? like you just keep changing the structure around and calculating the formal charge until you find it?

Matthew 1C

What is it that allows elements to be excepted from the octet rule? How do we know how many more electrons the element can carry?

Matthew 1C

^ this is because potassium and calcium don't have electrons that occupy the 3d orbital, whereas elements after do.

Matthew 1C

Does that mean that when doing configurations it doesn't matter if we choose clockwise or counterclockwise spin for single electrons? Or is there a preference?

Matthew 1C

a) Use the Rydberg formula for atomic hydrogen to calculate the wavelength of radiation generated by the transition from n=4 to n=2. I understand the calculation of the change in energy, but in calculating the wavelength using the equation lambda= ch/E, why do we discard the negative?

Matthew 1C

How do we know which is the initial or final n when using the Rydberg formula? What is the reasoning for knowing that n=1 should be used for the n initial in the equation?

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