CHEMISTRY COMMUNITY

Shivam Rana 1D

The instantaneous rate should decrease with time.

Shivam Rana 1D

I think you would need experimental data to determine this.

Shivam Rana 1D

It depends on where the dilution takes place but diluting the cathode solution should decrease the cell potential.

Shivam Rana 1D

Salt bridge is usually made of inert anions and cations that balance out charge buildup.

Shivam Rana 1D

Since the electrode is a solid it is not factored into the equilibrium constant and therefore increasing or decreasing its mass will not affect the Ecell.

Shivam Rana 1D

cell potential does not change with the mass of electrodes.

Shivam Rana 1D

A galvanic cell prodices electrical energy and an electrolytic cell produces chemical energy.

Shivam Rana 1D

I don't think we need to know about fractional and negative orders.

Shivam Rana 1D

I think the "concentration" of solids and liquids is not included in the rate law.

Shivam Rana 1D

Rechargeable batteries use reversible chemical reactions. Chemical reactions used in non rechargeable batteries are irreversible when a current is passed in the reverse direction

Shivam Rana 1D

I can think of two main ones: G=-nFE and G=-RTlnQ

Shivam Rana 1D

H2O is used to intially balance the oxygens, then H+ to balance the hydrogens, and then e- to balance the charge.

Shivam Rana 1D

I think these are the half reactions:
Cl-(aq) --> Cl2(g) + 2e-
MnO4- + 5e- --> Mn2+

Shivam Rana 1D

To prevent charge buildup

Shivam Rana 1D

You would need experimental data to find the rate of the reaction. I don't think its possible to determine the effects of the temp change without experimental data.

Shivam Rana 1D

You will have a different K at different temperatures since the equilibrium concentrations vary with temperature.

Shivam Rana 1D

You can find the K using the delta g value and the delta G0 value. The van't hoff equation may help.

Shivam Rana 1D

The n in -nFE represents the mole of electrons transferred in a redox reaction.

Shivam Rana 1D

A salt bridge will contain stable anions and cations like Na+ and NO3- which will migrate to the anode and cathodes to prevent charge buildup when electrons flow from the anode to the cathode.

Shivam Rana 1D

Delta G0 is given under standard conditions whereas delta G is given for modified conditions.

Shivam Rana 1D

Entropy can also equal zero at absolute zero when the molecules only have one orientable state (no residual entropy).

Shivam Rana 1D

For a pressure versus volume graph a reversible process, which is usually isothermic, will be a curved line. An irreversible reaction will be a straight line.

Shivam Rana 1D

Isochoric means at the same volume.

Shivam Rana 1D

A redox reaction is any reaction in which the oxidation numbers of an atom is changed by the transfer of electrons.

Shivam Rana 1D

You want to use the equation with ln in it when you are trying to figure out the delta G at non-equilibrium concentrations.

Shivam Rana 1D

If work is being done on the system the free energy is increasing because the external environment is transferring energy to the internal system and when the system is doing work like expansion that energy is being transferred outside.

Shivam Rana 1D

Reversible reactions will have a Kc between 10^-3 and 10^3

Shivam Rana 1D

At constant volume, the heat goes towards raising temperature but at constant pressure, some go towards work.

Shivam Rana 1D

Maximum means that all possible energy states have been realized.

Shivam Rana 1D

I think you would need to first relate the work to heat and then heat to entropy as shown in class today.

Shivam Rana 1D

A closed system cannot exchange mass with its surroundings but it can exchange energy, while an isolated system cannot exchange either.

Shivam Rana 1D

That is the specific heat of water, the amount of energy needed to raise one gram of water one degree celcius.

Shivam Rana 1D

Steam at 100 degrees will contain more energy than water at 100 degrees because of the phase change (the flat line on the heating curve).

Shivam Rana 1D

Using this method is less accurate and takes longer because all the bonds need to be broken and reformed. It is less accurate because the bond enthalpies are averages, not exact values.

Shivam Rana 1D

Hess's law is used to find the change in enthalpy. It states that regardless of the pathway taken to reach a final product, the change in enthalpy will be the same. This is because enthalpy is a state function.

Shivam Rana 1D

water is included in the Kp expression if it is a vapor.

Shivam Rana 1D

We're not at buffers yet, I don't think you'll need to do a buffer problem.

Shivam Rana 1D

Delta H and q measure two different things even though they may be related. Q measures work while dH measures enthalpy which only depends on initial and final conditions.

Shivam Rana 1D

Solids are not in solution because they are not dissolved, and thus there exists no concentration for solids. solids function as a pure substance

Shivam Rana 1D

When you cancel out the x and solve. You see if the x value is less than 5% afterwards.

Shivam Rana 1D

All strong acid and base cations/anions will not affect the pH of the solution.

Shivam Rana 1D

You multiply the two kc values.

Shivam Rana 1D

The equilibrium constant will only change when there is a change in the temperature. Otherwise, the Kc does not change, only the Q will change.

Shivam Rana 1D

I think it would be good to know this information just in case it shows up on the test.

Shivam Rana 1D

I think this would produce both an acid and base in water. The Ka and Kb values would need to be compared to determine which character would be prevalent.

Shivam Rana 1D

Inert gases do not affect the equilibriums of the gases already in the container because they are not part of the reaction.

Shivam Rana 1D

Kc and Kp would not be the same values and i think there is a way to convert between the two for gases.

Shivam Rana 1D

Im assuming it will be on outline 1 and parts of outline 2.

Shivam Rana 1D

If you know 60% reacted then you know the moles that were used and you can use that to find the leftover moles for the other reactant and the moles of product made. You can use these new concentrations to find the equilibrium constant.

Shivam Rana 1D

For pressure the equilibrium moves towards the side with the lower moles, what Dr. Lavelle showed in class Friday.

Shivam Rana 1D

There are 4 spots for hydrogen bonding on H20

Shivam Rana 1D

This depends on the flexibility of the ligand (whether it can rotate) and the locations of the lone pairs. Might be best to just memorize the sheet that is on the website because its difficult to determine the denticity sometimes.

Shivam Rana 1D

You do not need to know this for the test if I am right. I think that was all an introduction for Chem 14b.

Shivam Rana 1D

The bicarbonate ion will react with a H30+ when it is acting like a base to make carbonic acid and water.

Shivam Rana 1D

NH4+ is not a ligand if I am right. I think the other two are just spelling conventions.

Shivam Rana 1D

This is just the convention for iron based on its latin name and periodic symbol.

Shivam Rana 1D

probably stronger b/c there is direct electron sharing in the bonds for coordination compounds.

Shivam Rana 1D

i think the sum of the pKa and pKb should be 14.

Shivam Rana 1D

Water is not large enough to wrap around and bind in two places. The lone pairs are only on the oxygen, they need to be physically spread apart by being on two different atoms for a ligand to be a polydentate.

Shivam Rana 1D

I think the coordination number is based on the number of ligands bound to the transition metal. I'm guessing lone pairs may play a role in determining how many ligands can bind to the transition metal.

Shivam Rana 1D

I think this would depend on the presence of other compounds present in solution. Also would depend on the concentration of OH- or H30+ in the water, since amphoteric compounds act like a buffer. If I remember correctly the pKa of the buffer (amphoteric compound) is what the solution will try to bal...

Shivam Rana 1D

I think it is 2-

Shivam Rana 1D

I think this means that the metal is inorganic but it is bound to organic ligands like diethyldiamine.

Shivam Rana 1D

There is a naming sheet for ligands. You just need to memorize these

Shivam Rana 1D

you count the number of lone pairs + bonds (regardless of bond type). for example, 2 bonds with one lone pair would be sp2. 2 bonds by themselves would be sp.

Shivam Rana 1D

if the question is aqua v hydrate, aqua refers to water that is within the coordination sphere and bound to the transition metal.

Shivam Rana 1D

You need to understand VSEPR theory and atomic trends to help you determine the type of IM force present.

Shivam Rana 1D

when a double bond is formed, you have one sigma bond or an S orbital interaction and one pi bond or p orbital interaction which fixes the bond in place (non-rotatable). you can only have on sigma bond b/c there is only one s orbital.

Shivam Rana 1D

Larger molecules and atoms are also more massive, and therefore, it takes more energy to make that substance change states.

Shivam Rana 1D

Induced dipoles occur when polar molecules cause shifts in the electron density of non-polar molecules.

Shivam Rana 1D

You can also think of strength by how diffuse each type of pair is. Therefore, because the lone pair is the most diffuse, it is the most repulsive. Lone pairs also have lower effective nuclear charge acting on them.

Shivam Rana 1D

Electron distortion is when electron densities are shifted. This can only happen if electrons are loosely held so they can move more, or in other words, an atom that is more polarizable.

Shivam Rana 1D

When two polar molecules interact that is a simple dipole dipole interaction where the positive regions of the opposing molecules align with the negative regions of the other. Dipole induced dipole induced occurs when electron densities shift spontaneously and positive and negative regions randomly ...

Shivam Rana 1D

Usually the length (which correlates to strength) of a bond is a factor that determines the energy stored in a bond. These values are determined experimentally, however.

Shivam Rana 1D

Instantaneous dipoles occur in all molecules. Electrons exist in the orbitals which are in theory just regions where the electron is most probably found. These electrons are in continuous motion all across the molecule, and therefore, they may randomly and spontaneously congregate in one region crea...

Shivam Rana 1D

Instantaneous dipole moments, like Van der Waals forces, last for fractions of seconds in the sense that the electron densities continually shift causing continual and sporadic interactions in different regions of the two molecules.

Shivam Rana 1D

If n is 12 what can l be? What can ml be?

Shivam Rana 1D

Does polarizability apply to both cations and anions?

Shivam Rana 1D

Whats the maximum number of electrons an expanded octet can have?

Shivam Rana 1D

What would be three resonance structures for SO2? Having S with an expanded octet and two double bonds and a lone pair seems to be the most stable due to formal charge. However, experimental evidence suggests that there is one single and one double bond on the S. On the test if we were given a quest...

Shivam Rana 1D

I think that amplitude would determine energy if light acted as a classical wave and any light with enough intensity could excite electrons if shined at the right amplitude.

Shivam Rana 1D

This hasn't been discussed yet, but I am more familiar with the arrow pointing towards the more negative region since the electrons would shift that way.

Shivam Rana 1D

Probably just a typo. The problem does ask for power so Watts is the correct unit

Shivam Rana 1D

Does dimethyl ether make a hydrogen bond?

Shivam Rana 1D

An electron is moved from the s subshell to the d subshell when an atom is at d^4 because then all the subshells would be singly filled and this is more stable.

Shivam Rana 1D

Are you referring to nodes? Electrons exist in hybridized orbitals when molecules form.

Shivam Rana 1D

I don't think we need to be able to calculate electronegativity values right now

Shivam Rana 1D

Electronegativity is the measure of an atoms tendency to attract an electron. Atoms at the right of the table are close to filling an octet and are therefore more electronegative.

Shivam Rana 1D

This is done because that adding electrons with parallel spins into different orbitals is a more stable configuration.

Shivam Rana 1D

Paired e- are electrons that occupy the same orbital in a subhsell with opposite spins. Electrons that independently occupy multiple orbitals in a subshell with the same spin are parallel.

Shivam Rana 1D

A and C do not work. Correlate each subshell to its quantum number.

Shivam Rana 1D

(a)3 (b) 5 (c) 1 (d)7
Correlate subshells to l values. Ex. p is 1

Shivam Rana 1D

You can use De Broglie's equation to find the wavelength.

Shivam Rana 1D

a) 1; (b) 5; (c) 3; (d) 7
orbitals for l can be calculated by 2l+1

Shivam Rana 1D

I think you only need to know the purpose of Schrodinger's Eq., there is no further use of it than that in our class. Know that the square of the wave function represents probablilty density and that the solutions to a wave equation are quantum numbers.

Shivam Rana 1D

I'd start by finding where 102.6 nm falls in the EM spectrum (this will help you understand what series you are in for hydrogen). After this you can calculate the energy for the photon and then find n2.

Shivam Rana 1D

Sodium has one unpaired electron in the 3s subshell, thus it is more inclined to lose that electron. If it loses that electron to an electronegative atom like chlorine the subshells are "satisfied" because the valence electrons are balanced in a "full" subshell. Aluminum requires...

Shivam Rana 1D

As the photon excites the electron it transfers its energy to the electron, thus the electron gaining energy. when the electron falls to its original level it emits a photon of the same energy; it loses energy in this phase as a new photon gains that energy.

Shivam Rana 1D

I know that there was a problem on the quantum hw that said an electron is excited by UV light and knowing the details about the lyman series makes the problem easier.

Shivam Rana 1D

Just adding to the previous responses, as mentioned in lecture because energy is quantized you need a specific wavelength of light for an electron to jump from one level to a higher energy level. Atomic emission spectra have bands that are isolated in specific regions; like how the Lyman series is i...

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