CHEMISTRY COMMUNITY

Leanne Wong 1H

Iodine vapor has a larger entropy than bromine vapor because the element iodine is larger and more electrons, therefore, there is more possibility of obtaining higher states.

Leanne Wong 1H

there would be no difference if the catalyst was homogeneous or heterogeneous that would change how the catalyst affects the activation energy or delta G.

Leanne Wong 1H

There would be a high possibility that the ochem discussed in class would appear in the test because for the chem14a final with Lavelle, he had a question on hemoglobin that he briefly touched upon in lecture.

Leanne Wong 1H

The answer should be in mmol/Lxs and there's no need to change L. If anything, you should just convert mmol to mol to get the answer in mol/LxS.

Leanne Wong 1H

The reaction rate is given in M/s because its the change in concentration over time where M is molarity which could also be written as mol/L.

Leanne Wong 1H

yes, it depends on the mole to mole ratio in the reaction.

Leanne Wong 1H

The best way to determine if something is an anode or cathode, you would look if the electrons are gained or lost.

Leanne Wong 1H

Yes, you have to multiply the coefficient with the charges because the charge is only for one atom/molecule so if you have multiple of the same molecules/atom then you have to multiply the charge by the coefficient.

Leanne Wong 1H

Did you know that you can cool yourself to -273.15˚C and still be 0K?

Leanne Wong 1H

O 3 is being reduced because you have to balance the half reaction of O 3 -> O 2 which would have H 2 O on the O 2 side which would then force there to be two hydrogen ions on the ozone side which means that it would also have 2e- on that side too. Therefore, ozone is reduced since it is gaining ele...

Leanne Wong 1H

In this case, n is the number of electrons involved in the reaction. You can determine it by balancing the half reactions.

Leanne Wong 1H

When the standard Gibbs free energy of formation is considered thermodynamically stable when it is negative because the pure compound is then considered to have a lower Gibbs free energy than the Gibbs free energy of the pure elements which would mean that the pure element would have the tendency to...

Leanne Wong 1H

it would all depend on which side is losing heat or not. the side that loses heat would be the one with the negative sign.

Leanne Wong 1H

Yes, it is because you are going from liquid to ice which is the opposite of fusion. You could also think of this in terms of the molecules gaining or losing heat since the molecule is going from liquid to ice, it is losing heat so deltaH would be negative.

Leanne Wong 1H

There is no relationship between the number of moles and entropy for 9.37d. Instead, it is because there is a tendency for disorder based on the second law of thermodynamics, therefore, the reaction would tend towards becoming more disordered. The key word in the problem is that it says it is decomp...

Leanne Wong 1H

You would calculate the degeneracy by the general formula: $(number of orientations)^{number of molecules}$
However, this is only true when you are given the number of molecules; if you are given the moles then you just do basic stoichiometry where 1 mole = 6.023x10^23 molecules.

Leanne Wong 1H

First Law: The conservation of energy (deltaU = w + q) Second Law: nature of entropy increases over time; tend toward disorder (deltaS = q/t) Third Law: the entropy of perfect crystal at absolute zero is equal to 0 (eqn derived from second law) It is perfectly fine to think it the way you have howev...

Leanne Wong 1H

Isothermal processes are processes at a constant temperature throughout the whole process so the temperature remains the same at the end. This would mean that the change in temperature would be the same values subtracting from each other which would equate to 0. Furthermore, the kinetic energy and p...

Leanne Wong 1H

Gibbs free energy determines the favorability of a reaction whereas S shows the change in entropy/"disorder".

Leanne Wong 1H

You determine the sign of entropy by the direction of heat flow.

Leanne Wong 1H

Gibbs free energy is considered a state function because Gibbs free energy is defined by the equation: G= H-TS where entropy and enthalpy are considered state functions therefore Gibb free energy is a state function.

Leanne Wong 1H

They are essentially the same thing. The only difference is what element/molecule is part of the reaction.

Leanne Wong 1H

Volume would not be necessary because specific heat capacity is in the units of Joules per grams and Celsius or Kelvin.

Leanne Wong 1H

Yes, they are the same because they are both state functions.

Leanne Wong 1H

you should always consider if first energy is being transferred such as heat/work then it narrows down the possible systems to the open or closed system. after you have to consider if matter is being transferred from the system to the surrounding.

Leanne Wong 1H

open system = matter and energy exchanged with the surrounding
closed system = only energy exchanged with the surrounding
isolated system = no matter or energy is exchanged with the surrounding

Leanne Wong 1H

Yes, you can because enthalpy is a state function.

Leanne Wong 1H

When you're calculating for the change in temperature, it doesn't matter what units of temperature it is in.

Leanne Wong 1H

Yes, it would be 524 + 340 because internal energy is the total store of energy in a system.

Leanne Wong 1H

For melting, work is negative because work is done by the system. For condensation, work is positive because work is done on the system. Furthermore, enthalpy and heat are correlated with work.

Leanne Wong 1H

pH is the measure of the concentration of hydrogen ions whereas pKa the acid dissociation constant and is able to predict what a molecule would do at specific pH.

Leanne Wong 1H

For a bronsted-lowry acid, the acid is a electron donor, whereas in a lewis acid, it is an electron acceptor.

Leanne Wong 1H

You can figure out if a molecule is monodentate, bidentate, tridentate, etc if you just draw out the lewis dot structure and see where there are lone pairs on the central atom.

Leanne Wong 1H

You would say Iron (II) however, you only use Ferrate (II) when you are naming the coordination compound.

Leanne Wong 1H

[] indicates the concentration of something. For example, [x] is the concentration of x in molarity.

Leanne Wong 1H

You know an element has an expanded octet when it has any d orbitals. This is because d orbitals are able to hold more electrons than s and p orbitals.

Leanne Wong 1H

Usually, you would just memorize the bond angles for the standard molecular shapes and when there is a lone pair, you know that the angles would be slightly less than the standard bond angle.

Leanne Wong 1H

In the second diagram posted above, can someone please explain the significance of the thicker line and the dotted line? The thicker line indicates that the bond is towards us and the dotted line shows that the bond is going away from us. This is to help represent the 3D shape of the molecule which...

Leanne Wong 1H

As long as you have the correct electron distribution and number of electrons, the shape shouldn't matter that much to Dr. Lavelle.

Leanne Wong 1H

yes, it's covalent because the electronegativity difference is literally 0, where its considered nonpolar.

Leanne Wong 1H

Unlike s and p orbitals, d orbitals can expand beyond the octet rule and xenon is so low on the periodic table, therefore, Xe is able to hold more than 8 electrons.

Leanne Wong 1H

No, only fundamentals and chapter 1-3 are going to be on the midterm.

Leanne Wong 1H

The reason why the two statements contradict is due to the fact that 4s orbital is lower in energy when 3d is only partially filled however when 3d is completely filled then it becomes lower than the 4s orbital.

Leanne Wong 1H

This is because for 3d and 4s orbitals, 4s orbitals must all be filled for 3d to be completely filled too.

Leanne Wong 1H

When you draw the electron configuration, it will determine if the electron is spin up or down.

Leanne Wong 1H

Yes, velocity should be in meters per second.

Leanne Wong 1H

After you solve for frequency, you use Rydberg's formula which is v (frequency) = R( $\frac{1}{n1^{2}}$ - $\frac{1}{n2^{2}}$ ). You always assume that n1 = 1, so you just plug in Ryberg's constant, n1 and frequency to solve for n2.

Leanne Wong 1H

When we're solving for the change in energy, it gives us the energy emitted by the electrons because of E (photon) - E (energy remove e-) = $E_{K}$ which is the energy of the electron emitted.

Leanne Wong 1H

Lavelle said in class that it would be given to us with the constant but my TA said that we should still know the conversion factors for future reference.

Leanne Wong 1H

Wavelength and frequency are inversely proportional to each other which means if frequency increases then wavelength decreases or vice versa.

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