CHEMISTRY COMMUNITY

Trent Yamamoto 2J

A rate is usually referred to as a positive number and already takes this into account

Trent Yamamoto 2J

Mariah wrote:
Brandi 2C wrote:** It's not on Sunday anymore. **

He said it was cancelled in the email!

But we are still having a final correct? We just don't have to be on campus.

Yes, we're still having a final. It'll be linked to Professor Lavelle's class website

Trent Yamamoto 2J

The Van't Hoff equation relates how temperature changes equilibrium

Trent Yamamoto 2J

Q= [anode]/[cathode]

Trent Yamamoto 2J

Ecell(o) is the standard potential, while Ecell is the overall potential of the cell

Trent Yamamoto 2J

Ghadir Seder 1G wrote:Can there please be a livestream for this review session that can be posted for reference after as well? This is absolutely the most helpful thing :(

Since classes are canceled, will the session still be happening or is it going to be recorded on zoom/bruincast/an online alternative?

Trent Yamamoto 2J

My test 2 was also updated in the grade book, so I'm guessing there should be an email on returning it soon

Trent Yamamoto 2J

Why are we able to use O2 to balance the O for reduction and oxidation?

Trent Yamamoto 2J

Can someone explain how to break down the oxidation and reduction half reactions? Au+(aq) --> Au(s) + Au^3+(aq)
I understand how you would use Au+-->Au(s), but why would you use Au^3+-->Au(s)?

Trent Yamamoto 2J

Why is the value of n in Delta G= -nFEcell equal to 2? How do we determine the value of n in any general rxn?

Trent Yamamoto 2J

Yes! Galvanic cells are always spontaneous

Trent Yamamoto 2J

H+ is added to balance H in acidic reactions while OH- is added in basic reactions to the opposite side of the reaction to balance the H20 molecule(s)

Trent Yamamoto 2J

You would use H+. Using H30+ would add more H's and an additional O to balance

Trent Yamamoto 2J

DesireBrown1J wrote:How do I access Sapling Learning?

I tried accessing it on a link he sent in one of his emails, but it required a payment method. The instructions said there was a way to avoid payment but I didn't see it.

Trent Yamamoto 2J

The Van't Hoff Equation helps relate K to the different values of T, since T affects K.

Trent Yamamoto 2J

Has anyone tried the Sapling Learning supplements that Dr. Lavelle has prepared? I was wondering how beneficial it has been for other people.

Trent Yamamoto 2J

I found the midterm difficult as well, mainly because I focused most of my time on studying the procedures for solving problems rather than understanding the conceptual material (which hurt my score the most). I had a similar experience in 14A, but I learned I have to just pick my head up and have s...

Trent Yamamoto 2J

Electrons will always go in the direction of the anode to the cathode

Trent Yamamoto 2J

If the standard reaction potential is positive, then the reaction is spontaneous

Trent Yamamoto 2J

Mitchell Koss 4G wrote:The same elements usually have the same oxidation numbers. The periodic table also has trends.

Can someone explain the periodic trends please?

Trent Yamamoto 2J

By separating the redox reactions, this means that the oxidation half is separated from the reduction half

Trent Yamamoto 2J

In a chemical reaction, there is an electric current that is produced and vice versa (such as when recharging a battery).

Trent Yamamoto 2J

By definition, oxidation is when there is a loss of electrons (oxidation increases) and reduction is when there is a gain of electrons (oxidation decreases)

Trent Yamamoto 2J

Delta G will not be constant because it is dependent on temperature and the temperatures will be different.

Trent Yamamoto 2J

Since K is influenced by temperature, this is why there are separate K values for differing T values

Trent Yamamoto 2J

The Van't Hoff Equation is used to find the temperature dependence of K and can be used to calculate K at a different temperature if delta H is known. Additionally, the difference between two Van't Hoff Equations can be evaluated to find lnK2-lnK1 (given that delta s and delta h are both constant).

Trent Yamamoto 2J

Based on today's lecture, Professor Lavelle said that it will be given either on the equation sheet or in the question

Trent Yamamoto 2J

Q is the heat released/absorbed and rev refers to the fact that the reaction is reversible

Trent Yamamoto 2J

They both mean the same thing, that is the reaction will occur on its own without additional energy

Trent Yamamoto 2J

Cp is used when there is constant pressure while Cv is used when there is constant volume

Trent Yamamoto 2J

In what instances will we know when temperature, pressure, or volume are held constant when calculating the change in entropy?

Trent Yamamoto 2J

Delta H is the easiest to determine if a reaction is positive or negative

Trent Yamamoto 2J

A phase change would mean that you would have to add the energy required for that phase change in order to calculate the overall enthalpy

Trent Yamamoto 2J

Unlike boiling water, steam experiences a phase change when it comes into contact with skin and thus releases a larger amount of heat that causes severe burns.

Trent Yamamoto 2J

For an open beaker, you are assuming that the only pressure against it would be constant air pressure (1atm)

Trent Yamamoto 2J

Hess's Law establishes that the total enthalpy change for the reaction is the sum of all changes.

Trent Yamamoto 2J

Check to see what you are given. Based on whether you are solving for specific heat capacity or q, then you would know whether or not to use the mass

Trent Yamamoto 2J

n a perfect system, q lost/gained by system = q gained/lost by surroundings. <--- may be negative

Trent Yamamoto 2J

Hess's Law states that the enthalpy change at each step can be added to give the total enthalpy change, so you would use this when given the Delta H rxn is given for the different steps.

Trent Yamamoto 2J

Given that there are 3 different methods to calculate the Delta H of a Reaction, which would be the most commonly used?

Trent Yamamoto 2J

Should just be from all material after the midterm, similar to 14a

Trent Yamamoto 2J

Bomb calorimeters would be used when you want to keep the volume constant. This would result in a pressure build up.

Trent Yamamoto 2J

Temperature is the only condition that will alter the K value. In an exothermic reaction, where heat is released, your constant will decrease. If the reaction is endothermic, where heat is absorbed, your constant will increase.

Trent Yamamoto 2J

You would set up an ICE table when given some significant value (ie. pH, pOH, K, etc.) and want to find the concentrations of the reactants and products in a chemical reaction. Usually questions tend to ask for the equilibrium concentrations after giving a K value and one initial concentration.

Trent Yamamoto 2J

You would use Kc when given molar concentrations of solutions in any state and Kp when you're given partial pressures only in the gas state

Trent Yamamoto 2J

Le Chatelier's Principle helps determine how a chemical equilibrium will adjust in order to minimize the effects of a certain change in a condition. For example, if the temperature increases in an endothermic reaction, there will be a shift towards the products in order to compensate.

Trent Yamamoto 2J

In an exothermic reaction, since heat is being released as a result of the reactants, increasing the temperature would shift towards those reactants. Vice versa for the products: decreasing temperature would shift towards the products.

Trent Yamamoto 2J

Can pH be negative and can pH/pOH be a number greater than 14?

Trent Yamamoto 2J

PV=nRT is used to convert from a pressure of a gas back into a concentration

Trent Yamamoto 2J

The R values are different depending on the temperature used in the reaction

Trent Yamamoto 2J

The 5% Rule essentially means you can approximate the value for x on an ice table because the value is so small it doesn't make a significant change in the concentration. For example, Professor Lavelle talked about how a millionaire giving away $1,000 would barely notice the difference.

Trent Yamamoto 2J

Usually the question will ask you to find the reaction quotient Q, which you will then compare to the given K to see if the reaction is already at equilibrium or if the reactants/products are favored.

Trent Yamamoto 2J

In my discussion my TA said we should know everything regarding chemical equilibrium and acids/bases

Trent Yamamoto 2J

Just confirming, when calculating for K or Q, the concentrations will have to be converted into moles/liter if the concentrations given are in mmol correct?

Trent Yamamoto 2J

This is the chemical equation that you should know

H2O + CO2 --> H2CO3

Trent Yamamoto 2J

Having more one more O will increase stability because the negative charge is dispersed more, which increases stability.

Trent Yamamoto 2J

A conjugate base is what is left of an acid when a proton is removed

Trent Yamamoto 2J

What is the significance of an amphiprotic compound?

Trent Yamamoto 2J

You can go down the outlines on his website as well, understanding those concepts will be important

Trent Yamamoto 2J

An amphoteric compound can either accept or donate protons/hydrogen atoms.

Trent Yamamoto 2J

I believe that he will also be doing practice problems this week that should help prepare us for the final

Trent Yamamoto 2J

What should we know about Vitamin B12 for the final?

Trent Yamamoto 2J

Cisplatin is a chemotherapy drug that stops cell division by forming a coordination compound with DNA by bonding with the N7 Guanine lone pair. It is important to note that Transplatin does not have the same effect because the Cl's are on opposite sides.

Trent Yamamoto 2J

Transition metals are located in the d-block (groups 3-12)

Trent Yamamoto 2J

Electron configuration is the arrangement of the electrons in a molecule. However, the molecular shape doesn't necessarily follow the electron configuration (though it is influenced by it). For example, a molecule could have a tetrahedral electron configuration but if it has a lone pair, that means ...

Trent Yamamoto 2J

In regards to our class, should we use the Bronsted definition or Lewis definition?

Trent Yamamoto 2J

Why do transition metal cations specifically form complexes?

Trent Yamamoto 2J

A ring structure forms when a chelate forms a ring of atoms around the central metal atom. Another example would be [CoN4(CH2)4].

Trent Yamamoto 2J

A coordinate number represents the number of bonds with ligands attached to the central atom. For example, [Fe(CN)6]^4- has a coordination # of 6.

Trent Yamamoto 2J

Cisplatin forms a coordination compound with DNA, which stops the rapid and controllable cell division of cancer cells. However, it does not single out cancer cells specifically, and can stop the division of normal cells as well

Trent Yamamoto 2J

Can someone explain why there are dipole-dipole forces present in 3.F.1 c and d?

Trent Yamamoto 2J

What is the order for the strength of interionic and intermolecular forces?

Trent Yamamoto 2J

From what I've read the curve occurs after the final, but usually it doesn't deviate too much from the standard 70% C, 80% B, and 90% A scale.

Trent Yamamoto 2J

Dr. Lavelle also explicitly said Hybridization would not be on Test 2

Trent Yamamoto 2J

lone pair - lone pair has the strongest repulsion, lone pair - atom has the second strongest repulsion, and atom -atom has the least strongest repulsion.

Trent Yamamoto 2J

The bond angles usually follow the same sort of pattern based on regions of electron concentration. It is important to keep in mind the lone pairs though, because these will decrease the expected bond angle.

Trent Yamamoto 2J

I do also know that Dr. Lavelle said that he would focus on covering sigma and pie bonds on Monday, so if he doesn't mention those then I would go over them anyways

Trent Yamamoto 2J

Andrea_3F wrote:So can dipole moments be temporary or all they all permanent?

I believe dipole moments are permanent

Trent Yamamoto 2J

I believe you can also recognize a dipole moment when there is a polar covalent bond, which by definition is when electrons in a covalent bond are not equally shared.

Trent Yamamoto 2J

Yes, there are electrons in every atom and these cause these forces

Trent Yamamoto 2J

Which intermolecular force increases boiling point the most?

Trent Yamamoto 2J

Why is dissociation energy, which is required to break a bond, always positive?

Trent Yamamoto 2J

How would you determine which bond has greater ionic character between HCl and HI?

Trent Yamamoto 2J

Does a coordinate covalent bond only occur with Lewis acids and Bases? (I know Boron Trifluoride was given as an example)

Trent Yamamoto 2J

Lewis structures with expanded octets have lower energy than with the regular octet structure (comparing the formal charge), so is it more stable and therefore more favorable to draw structures with expanded octets?

Trent Yamamoto 2J

Why can atoms in the third period or higher accommodate more than 8 valence electrons?

Trent Yamamoto 2J

Why are highly distorted electrons described as being highly polarizable? Which characteristics result in the ionic bond being more covalent in character?

Trent Yamamoto 2J

Kevin Antony 1J wrote:From what I gather, you know have energy per electron. We know there are 6.022 x 10^23 electrons in a mol. If you divide by Avagadro's number you should get energy per mol.

That makes sense, thank you!

Trent Yamamoto 2J

During my discussion, it was mentioned that when drawing resonance structures that if, let's say there's two double bonds, you can hold that one double bond constant and rotate the other around to other pairs. Would this account for all of the possible answers that would be required for a question a...

Trent Yamamoto 2J

In the Heisenberg Indeterminacy Module, question 22 asked for the uncertainty in kinetic energy (which I was able to calculate) and the conversion of that into moles. How would I do that?

Trent Yamamoto 2J

When we're solving for the initial energy level in a transition using E=hv and E= -hR/(n^2 final) + hR/(n^2 initial), should the manipulation to find the initial energy level be done at the beginning of the problem to isolate n initial or should you just plug in the values and solve for it algebraic...

Trent Yamamoto 2J

The x is in reference to the plane, among the x, y, and z planes

Trent Yamamoto 2J

My key takeaway from the experiment was that electrons have different spins (spin up vs. spin down), which create different electric fields.

Trent Yamamoto 2J

A Hamiltonian is a second derivative (ie. d/dx[sinx]= cosx d/dx[cosx]= -sinx)

Trent Yamamoto 2J

Hi! I've found it very helpful to take lecture notes on a notepad, then the following day condensing the notes into a separate notebook. I've found it really useful in helping the information stick and it makes referring to my notes so much easier. It'll also help having a notebook full of notes for...

Trent Yamamoto 2J

What specifically makes the answer from the incorrect atom model's (electron located inside of the nucleus) application of the Heisenberg Equation 'unrealistic?'

Trent Yamamoto 2J

At the end of today's lecture, Lavelle wrote some PSI values on the board and said that they were untrue. One of them was PSI (1, 1, 0, +1/2); can someone explain why this wouldn't be able to exist?

Trent Yamamoto 2J

DeBroglie is used when detecting extremely small masses (unlike the car example in lecture).

Trent Yamamoto 2J

e=hv is in regards to energy per photon, which directly relates to light.

Trent Yamamoto 2J

De Broglie is applied when we are solving for an object's wavelength, and the the resting mass is given. For example, it could be the baseball being hit or a car moving.

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