CHEMISTRY COMMUNITY

katie_sutton1B

Also, a positive E means a -delta G, which is a spontaneous reaction. This comes from the equation deltaG=-nFE

katie_sutton1B

Catalysts are not used up in the reaction. Rather, they just lower the activation energy of the reaction.

katie_sutton1B

He was pretty lenient last quarter and if you had missed a couple he still gave full points, so it should be the same.

katie_sutton1B

A large K means that there are more products than reactants at equilibrium. This means the products are more stable than the reactants, because reactions generally proceed to form the most stable things possible. Therefore, forming SO3 is more stable than forming SO2 and O2.

katie_sutton1B

Yes, zero order is independent of the concentration of reactants. This has a graph that has concentration as its y-axis, and time as the x-axis.

katie_sutton1B

The reaction rate or rate of reaction is the speed at which reactants are converted into products.
The formation rate is the rate that products are being formed.
The two definitions are very similar.

katie_sutton1B

Basically, if there is no solid, you add Pt as your cathode or anode because it does not affect the reaction as it is an inert solid.

katie_sutton1B

Don't forget that n=1 is usually assumed, so it might not be explicitly said.

katie_sutton1B

Yes, It will be a straight line. But I think Lavelle also said if you also see an exponential decrease, that would be [A] graphed and indicate a first order reaction as well

katie_sutton1B

To add on, a single vertical line represents an interface between phases - reactant|product. And a Salt Bridge consists of a gel containing a concentrated aqueous salt solution in an inverted U-tube. This allows the ions to flow without affecting the concentration and is denoted by double lines ॥

katie_sutton1B

The oxidation number for H is +1, so 6*(+1)=6.
The oxidation number for O is -2, so 1*(-2)=-2
Together that equals 4. Since there is no charge on the compound, set it equal to zero
2 (C) + 4 = 0
C=-4/2, C=-2

katie_sutton1B

In the seventh edition, it says to set delta G = to zero and solve for T to find the range of temperature using deltaG=delatH - TdeltaS. Any number from 0 to the found T value will be a spontaneous reaction.

katie_sutton1B

K indicates equilibrium, so you would use that equation for a reaction at equilibrium. You would use Q when it not.

katie_sutton1B

At zero, there is no more work that can be done, and the reaction does not favor either the reactants or products. Thus, it is at equilibrium.

katie_sutton1B

delta G knot indicates standard conditions, while regular delta G is the change in free energy under other conditions

katie_sutton1B

Also, deltaU = 0 for the isothermal reaction(or compression) of an ideal gas.

katie_sutton1B

Entropy is, in simple terms, how many ways an object can position itself. Therefore, the higher the entropy is based on how complicated the molecule is. The more complicated, the more shapes it can form, and therefore the more entropy. This then means that entropy goes in the order gas>liquid>solid,...

katie_sutton1B

Basically - Isothermic, Reversible --> w=-nRTln(v2/v1)
Irreversible --> w = -P ΔV

katie_sutton1B

You want to use the moles to find the concentration by dividing by the volume. The coefficients of the balanced equation give you your exponent.

katie_sutton1B

Since a solid is compact and the molecules do not move, it has less entropy. Since gas molecules are very spread out, they have more disorder and therefore more entropy.

katie_sutton1B

Energy is the ability of a system to do work and the change of energy, while heat is the energy being transferred.

katie_sutton1B

Glucose is used to form ATP, which is the actual stored energy that the heart uses. So breaking glucose bonds is not the direct source of energy.

katie_sutton1B

An inert gas does not react with the species in the reactions. Therefore, it does not affect any of the concentrations, and K remains the same

katie_sutton1B

You want to look at which side has less moles of gas, once it is equilibrium and balanced. Increasing the pressure forces the reaction to decrease the amount of moles, therefore going towards whichever direction has the least amount of moles. And vice versa for decreasing pressure

katie_sutton1B

Also, t the end of the equation it might give you delta H. If it is positive it is endothermic, while negative is exothermic.

katie_sutton1B

Also, if the question asks for Kc you know you need to use concentration

katie_sutton1B

K does not change because it is a constant. If you remove products, the reaction would move to favor the production of more products to reestablish equilibrium. Therefore it would be Q that would change

katie_sutton1B

Blanking an equation gives you the correct stoichiometric values for the equation. This is important because you have to raise the concentration of a species to its stoichiometric concentration to get the correct Kc

katie_sutton1B

Kp is only used for gases, so you won't be able to use liquids or solids for that reaction. But for reactions with liquids, solids, and aqueous, then no, you do not include liquids or solids. This is because a pure substance does not really have a concentration and therefore does not affect the equa...

katie_sutton1B

Endothermic reactions requires heat, and can basically be included as a reactant of the formation. Exothermic releases heat, and can be thought of as a product.

katie_sutton1B

Since both anions have an H, they can donate it to a base. This means it can be acidic. I also believe that H2PO4- can donate two protons, but i'm not quite sure

katie_sutton1B

After identifying the intermolecular forces, you would want to look at the size, or amount of electrons in the atom. The more electrons there are, the more polarizable it is. The more polarizable element has the strongest Van der Waals forces and therefore Se would be the higher boiling point.

katie_sutton1B

Generally it will be the protons that are farthest from the central atom. You also want to check stability of the Lewis Structure after the deprotonation.

katie_sutton1B

I think he wanted to show where the lone pairs on the atoms bonded together. They are the exact same, just one accurately shows the bonding.

katie_sutton1B

Yes, the charge is mandatory to know when naming compounds because you have to be able to make it neutral or charged, depending on what the question is asking

katie_sutton1B

To figure out the hybridization, you just count the number of electron density areas. Then, you equate it to the orbital levels. For example, if you have three electron density regions, you would write sp2 (s has 1 and p has 2). P can have up to three, and d can have up to 5

katie_sutton1B

I believe that would be stated directly in the question. If asked for molecular geometry, then you would give the VSEPR geometry which excludes the lone pair in naming the shape. If asked for electron domain geometry, then you would give the shape which includes the lone pairs

katie_sutton1B

A sigma bond is stronger because of the head to head overlapping, while a pi bond is weaker because of side to side overlapping. A sigma bond requires more energy to break than a pi bond does.

katie_sutton1B

Electron density is given by all regions that have electrons, including both lone pairs and bonded atoms. However, the molecular geometry refers only to the atoms that are bonded to the central atom.

katie_sutton1B

Yes it would be because the dipole moments do not cancel out

katie_sutton1B

I think you have to look at N as the central atom. So you would draw the Lewis Structure relative to each nitrogen, and bond them together. This would make it trigonal pyramidal

katie_sutton1B

Electron density geometry takes into account all the bonded regions between two atoms, as well as the lone pairs. However, molecular geometry is just the bonded regions of atoms in a molecule.

katie_sutton1B

How may should we have by now?

katie_sutton1B

Will we be tested on lewis structures again?

katie_sutton1B

They bond with O,N,and F and are dipole-duple bonds

katie_sutton1B

It's obviously better if you do because of partial credit, but it's not necessary.

katie_sutton1B

What would be an example problem that includes the concepts of coordinate covalent bonds?

katie_sutton1B

Ions will have to have a formal charge, but that could be stated in the chemical formula given. For example, BrO- will have a formal charge of -1. There will be 6 lone pairs on Br, a covalent bond to O, with 6 lone pairs on O. This gives Br a formal charge of 0, and O a formal charge of -1. (FC = va...

katie_sutton1B

He said we wouldn't have to

katie_sutton1B

Is this the one where you would just square the value of (n) level to find the degeneracy?

katie_sutton1B

It decreases across a period (left to right) and increases down a group (top to bottom).

katie_sutton1B

This was not discussed in lecture to the best of my memory either. Because degenerate orbitals are when there are two orbitals of the same energy, all you have to do is square the (n) level.

katie_sutton1B

Will he be testing on anything related to test 1?

katie_sutton1B

So I get the conversion, but what exactly is an eV and what the difference between eV and J? Do they both measure energy?

katie_sutton1B

I'm also confused. I thought Lavelle said we didn't have to know how to solve questions with Schroedinger's equation. Is it rydberg or schroedinger?

katie_sutton1B

This spectroscopic analysis of light shows only photons of particular energy. By looking at the energy levels of the excited atoms, you can form the structure of your element and identify it.

katie_sutton1B

The atomic spectra is the spectroscopic analysis of light given off by excited atoms, and shows only photons of a particular energy given off. The experiment takes the energy of the photon, and identifies its energy level. Then, using these energy levels, you can see the electronic structure of the ...

katie_sutton1B

A photon must be able to reach the threshold energy required to eject an electron. Consider that the longer the wavelength, the lower the frequency, and the energy off each photon is proportional to its frequency, given by E=hv. Therefore, shorter the wavelength is, the more energy it has.

katie_sutton1B

To add on, does this mean that the molar ration of one reactant to another is useless information in finding theoretical yield?

katie_sutton1B

To add onto this question, does it matter which order we put CO2 and H20 as the products? For example, can we write C6H6 + O2 --> H20 + CO2, or does it have to yield CO2 + H2O?

katie_sutton1B

I have not been able to find any good youtube videos either. I find it easier to balance chemical equations by checking them one at a time from reactant to product and isolating them (I do it in my head but if it's too long I write it down). It's not bad to write it once or twice if its more complic...

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