CHEMISTRY COMMUNITY

Niveda_B_3I

ln[A] vs time is the rate plot for a first order function.

Niveda_B_3I

The anode is oxidized, loses electrons.
The cathode is reduced, gains electrons.

Niveda_B_3I

The rate law depends on how quickly a product is formed, and that depends on how quickly the reactants used to make it up are used up.

Niveda_B_3I

The H+ would be with the Cr2O7 since the oxygen atoms in it are balanced with H20, and the H20 are balanced with H+

Niveda_B_3I

E^o is the standard reduction potential, or basically how badly the molecule wants to be reduced (positive means it wants to be reduced more, negative means it wants to be oxidized more). Ecell basically refers to the total standard reduction potential of the cell with E^o of the cathode - E^o of th...

Niveda_B_3I

Being reversible allows the cell to do more work!!!

Niveda_B_3I

Instantaneous change would imply a derivative, because you're finding the changing at a certain time t, versus average would be you finding the change over a period of time, from t1 to t2.

Niveda_B_3I

Kinetics tells you the rate of the reaction; a reaction might be deemed spontaneous due to thermodynamics, but sometimes that reaction occurs very slowly. Kinetics tells you how fast or slow that reaction occurs.

Niveda_B_3I

Isobaric basically means there is no change in pressure, which means you can have work and heat changing your internal energy.

Niveda_B_3I

Free energy is a state function, because it involves enthalpy and entropy, two other state functions.

Niveda_B_3I

It should cover whatever we learned on the Friday lecture of Week 6, and everything covered in Week 7.

Niveda_B_3I

Gibbs free energy is the amount of energy that is available to do work, and the equation shows the relationship between entropy and enthalpy as well.

Niveda_B_3I

Are reversible reactions are isothermal!

Niveda_B_3I

When you are calculating an entropy change due to pressure, and not volume.

Niveda_B_3I

The change in entropy would be zero when the heat transferred into or out of the system is 0.

Niveda_B_3I

The change in internal energy could be 0
if q = -w
if T = 0
and if the system is isothermal and the reaction is reversible

Niveda_B_3I

Cv is for when volume is constant, and Cp is used for when pressure is constant.

Niveda_B_3I

-PdeltaV would be used if your external pressure is constant, and with irreversible reactions.

Niveda_B_3I

pressure of the system=the pressure of the exterior

Niveda_B_3I

We will have to know how to do calculations involving calorimetry.

Niveda_B_3I

On the other hand, entropy is basically the degree of disorder.

Niveda_B_3I

Your x has to be less than 5% of the initial concentration for your assumption/approximation to be valid

Niveda_B_3I

Not really. You'd have to use the Ka or Kb value to solve an ICE table and find the concentration of Hydronium ions to find that.

Niveda_B_3I

I had Lavelle last quarter, and the best way to study is to do the homework problems, and the practice worksheets that UA's like Karen and Lyndon give and attend their sessions. Also read (or at least skim) the textbook.

Niveda_B_3I

PV = nRT shows the relationship between pressure and concentration so it would be used to convert Kp to Kc and vice versa.

Niveda_B_3I

since it's a asalt, the potassium ions dissociate completely on both sides, and don't really count toward finding your equilibrium constant value.

Niveda_B_3I

Ka time Kb is Kw, and pKa + pKb is 14, and also equal to pKw

Niveda_B_3I

Kelvin is the SI unit for temperature.

Niveda_B_3I

However, make sure you remember that just because a reaction is at equilibrium, it doesn't necessarily mean that the reaction is over.

Niveda_B_3I

You can determine whether you should be using Kc or Kp depending on the states of the molecules in the chemical equation, or also the information given to you.

Niveda_B_3I

We know that potassium has a +1 charge, and we know that cyano has a -1 charge and there are 4 cyano so there's a -4 charge but nickelate has a +2 charge so in general the anion has a -2 charge. So there has to be 2 potassium ions so that it is a neutral compound.

Niveda_B_3I

The conjugate base is just the deprotonated acid.

Niveda_B_3I

There has to be a proton (aka hydrogen) that can be pulled off the acid and create a H3O+ ion to increase the acidity of the solution.

Niveda_B_3I

Coordination number is basically the number of bonded atoms to the central atom.

Niveda_B_3I

The stomach and digestive system in general have a layer of protection. Your ski is that layer of protection for the rest of your body (like the outside) so when you have a cut, there's no protection.

Niveda_B_3I

Probably both. What if you're asked to find the molarity of a solution that is made up of water and a compound but they give you the name of the compound rather than the molecular formula?

Niveda_B_3I

The arrangement of the electron density would be trigonal bipyramidal, but the arrangement of the atoms would be tetrahedral, since there's a lone pair. As a result, you would end up with seesaw structure.

Niveda_B_3I

Furthermore, sp3 means there's one sigma bond, sp2 means one sigma bond, one pi bond, and sp means there's one sigma bond and two pi bonds.

Niveda_B_3I

It's probably a good idea to know that, especially if it shows up in the textbook. We can probably assume from previous tests that it would be fair game for the test since the same thing happened with nodes on the second test.

Niveda_B_3I

A square planar has an octahedra; electron density arrangement, but since two of those areas of electron density are lone pairs, and only four atoms are bonded to the central atom, it is square planar in molecular shape.

Niveda_B_3I

Also, it's good to know that:

single bond - one sigma
double bond - one sigma, one pi
triple bond - one sigma, two pi

etc.

Niveda_B_3I

Basically the electron density arrangement is what would give you your hybridization orbitals. So if your electron density arrangement is tetrahedral, then you would have sp3 hybridization. However, your molecular shape is actually based on the number of atoms bonded to the central atom, so if you h...

Niveda_B_3I

Also, you wouldn't make the atom that has the most electronegativity a radical, because it would want a full octet.

Niveda_B_3I

The actual structure is the resonance hybrid, but we draw out the resonance structure to show the possible positions of the delocalized electrons.

Niveda_B_3I

Electron affinity is the amount of energy released when an atom is given an electron, and ionization energy is the energy not takes to remove an electron.

Niveda_B_3I

also, this half shell stability extends to things like Boron and why it doesn't need a full octet.

Niveda_B_3I

Also if you draw all the resonance structures, draw arrows between them!

Niveda_B_3I

It just symbolizes that the molecule is negatively charged, and that charge should be equal to your overall formal charge.

Niveda_B_3I

You just need to know trends, and maybe why the trends make sense.

Niveda_B_3I

The last shell is the valence shell, and the number of valence electrons is the number of electrons in the last shell (determined by n value).

Niveda_B_3I

Hydrogen bonds, from what I remember from high school chem, were the strongest intermolecular forces, but bonds are technically between molecules, which would explain why they're actually bonds like someone had mentioned earlier.

Niveda_B_3I

Hi Nikitha xD
Basically there's 3 p orbitals, px py and pz. The x,y, and z simply tell you the orientation of the orbitals. However, it doesn't really matter in terms of when you're doing electron configuration or anything like that.

Niveda_B_3I

Really, the concepts you should know based on Schrodinger's are the fact that there's different energy levels and the types of orbitals you can find at each one, as well as properties of them. (For example, the s-orbital is the only orbital with symmetric electron distribution).

Niveda_B_3I

Given that you know either the change in momentum or position, you should be able to find the minimum value of the other using Heisenberg's.

Niveda_B_3I

Basically, the work function (threshold energy) is going to be equal to the energy of the photon (hv) minus the kinetic energy of the electron upon removal (excess energy). Of course, if the threshold energy is not equal to or less than the energy of the photon, then the electron will not be removed...

Niveda_B_3I

Also, it's important to note that the energy of a photon is determined by E = hv, where h is Planck's constant and v is the frequency of light.

Niveda_B_3I

The threshold energy differs between various metals, just like the spectra for different elements is different. This is because the change in energy from level to level is different depending on the element.

Niveda_B_3I

Regardless of the heat, it's still a chemical reaction. So the Law of Conservation of Mass applies as it usually would, and you balance the equation normally.

Niveda_B_3I

It's never going to be completely accurate. You just have to round to the nearest whole number.

Niveda_B_3I

There's no such thing as an unacceptable % yield. % yield is simply the comparison of the actual yield to the theoretical yield.

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