CHEMISTRY COMMUNITY

Michael Du 1E

Thank you, Dr. Lavelle, for your hard work in these two quarters that I have had you! Chemistry was definitely difficult to learn but with your resources and chemistry community, I was able to get through it. We appreciate all you have done :)

Michael Du 1E

it said that all inorganic phosphate came from ATP so I assumed that the phosphate, as a result, had the same concentration as ATP which was 4 x 10^3 or something I believe. As a result, my reaction quotient equation was: ((ADP)(P)/(ATP) / (9 x 10^-6)(4 x 10^-3)/ (4 x 10^-3). However, I am not sure ...

Michael Du 1E

Can anyone please explain to me why when it is an isothermal reversible expansion, we can assume that internal energy is 0 and q = -w? Thank you

Michael Du 1E

Just for clarification, before we solve for the equilibrium constant, we have to make sure the chemical equation is balanced right? thank you

Michael Du 1E

When a reaction is in equilibrium, does that mean E cell is 0 and we can alter the equation to where it would be E cell (standard) = 0.0592/n x log K? Thanks

Michael Du 1E

In the review packet, 1a, what determines the fact that the lower concentration of the Ag+ (0.10M) is on the left anode side and the higher concentration (2.0 M) is in the cathode side of the concentration cell? or it doesn't matter, thanks!

Michael Du 1E

Why is it that the inert (Pt) is also inserted in the anode side when there is already a solid there? I understand why the Pt was inserted for the cathode side as both solutions were of an (aq) phase. Thanks!

Michael Du 1E

Just for clarification, a dead battery means that the E potential is 0 right, also implying that Delta G is 0? Thank you

Michael Du 1E

If Oxygen is left alone in a reaction without any charge, would its oxidation/ reduction number still be -2 or 0? Thank you

Michael Du 1E

Can anyone please explain why an endothermic reaction would have a higher activation energy than the reverse reaction? Thank you

Michael Du 1E

I'd say we would use it so calculate for the activation energy and maybe the rate constant if we are given the activation energy and temperature.

Michael Du 1E

Can anyone please explain to me on how to do 7b. 3c? Thank you

Michael Du 1E

Just for clarification, is the equation E cell = E cathode - E anode the same as simply adding the reduction potential for the cathode and the oxidization potential (the flipped number of the reduction potential) of the anode? thank you

Michael Du 1E

The anode would be on the left and cathode would be on the right. This way makes more sense as the flow of electrons goes from left to right. The electrons come from the anode side that is oxidized, taking to the other side for reduction.

Michael Du 1E

You would first have to add H20 in order to balance the O's and then add H+ to balance the H's.

Michael Du 1E

in order to find the n of the equation of DeltaG = -nFE, would I have to separate the equation into half redox reactions to see how many electrons there are? Or is there a shorter way to determine it, thank you!

Michael Du 1E

When solving for the standard gibbs free energy, how do I know when to use the products and reactants' gibbs free energy of formation and subtract them from each other or use the equation standard Delta G = standard delta H - T x standard delta S? Thank you

Michael Du 1E

For the problem, the solution manual changed standard Delta G into -RTlnK. How can we make the assumption that the reaction was in equilibrium when it wasn't mentioned on the problem?

Michael Du 1E

Under what conditions would Delta U = 0 and q = -w ? Thank you

Michael Du 1E

When calculating the q for the reaction why was -2.058 kJ divided by the moles of CO? thank you

Michael Du 1E

Can anyone please explain why q = delta U in the equation for the heat capacity at constant volume and why q = delta H in the equation for the heat capacity at constant pressure? Thank you

Michael Du 1E

Can anyone please explain why the delta internal energy for am isothermal expansion or compression of an ideal gas is zero? Thank you.

Michael Du 1E

Hi Michael Du 1E! The given value is the temperature change that the calorimeter experienced when the 3.50 kJ of heat was added to the calorimeter containing 200 mL of solution. Because the temperature change is the same as if it was in Celsius or Kelvin, you can interchange the units. Take for exa...

Michael Du 1E

For 4a13. how did the given 7.32 degrees celsius turn into 7.32 K according to the solution manual? or its just simply an error

Michael Du 1E

For the equation (heat given off by rxn = -heat absorbed by solution), why would the heat that is absorbed by the solution be a negative number? Wouldn't the solution be a positive q if it absorbed the heat? thank you

Michael Du 1E

Can anyone please clarify the differences between the reversible and irreversible process? thank you Yes, I am confused on this as well. I think I understand it now. When you're given a constant external pressure, it would be considered irreversible because once the gas expands the piston outward, ...

Michael Du 1E

I'm sure we have to know the equation for it. The textbook does a decent job in covering it.

Michael Du 1E

Is anyone else struggling with the content a bit? I felt like the lectures moved a bit too quick on the topics for me to process everything and to be able to work out the problems on the homework. Any advice to understand the content would be appreciated, thank you!

Michael Du 1E

Daniel Chen 2L wrote:So if the pressure of the system is not constant, then the formula is reversible?

correct
while if the pressure of the system is constant, it is irreversible

Michael Du 1E

Can anyone please clarify the differences between the reversible and irreversible process? thank you

Michael Du 1E

Since the diameter is given, we know the radius. Delta V also equals Area x distance so you can simply plug in the radius into the Area equation times the distance (20).

Michael Du 1E

What are the rules for the equilibrium shift by the change of pressure? Will the change of pressure only affect the equilibrium if the pressure change is caused by a change in volume? I believe I heard from somewhere that there will not be a shift in the equilibrium if only pressure is changed. Than...

Michael Du 1E

Can anyone explain to me how the calorimeter works? I only know the basics of it in which it measures the specific heat capacity. However, I believe he went more into detail on it with a picture of it etc. Thank you.

Michael Du 1E

Can anyone please explain to me the heating curve for water that was brought up at the end of lecture and the correlation as to why steam causes severe burns? Thank you!

Michael Du 1E

with the given pH we can convert that to the equilibrium concentration of H+ which would be 0.063. With this, we now know that x is also 0.063 as in your ICE table, the equation in finding the equilibrium concentration of H+ is 0 + x = 0.063. Because the equation is a 1:1 mol ratio, we can subtract ...

Michael Du 1E

How do we know if the given concentration of benzoic acid (0.110 M) is either the equilibrium concentration of initial concentration? Thank you!

Problem: "The percentage deprotonation of benzoic acid in a 0.110 M solution is 2.4%. What is the pH of the solution and the Ka of benzoic acid?"

Michael Du 1E

We use the ICE tables when the initial concentrations rather than the equilibrium concentrations are given meanwhile we can go straight to the K equation (products over reactants) when the equilibrium concentrations are already given.

Michael Du 1E

On 6D. 3, when finding the H30+ solution from the given pH (0.09 M), would it be the equilibrium concentration or initial? Thank you!

Michael Du 1E

When given a K that is small, does it have to be (< 10^-4) or (< 10^-3) to approximate the x values? thank you

Michael Du 1E

Given that the H3O+ concentration is 1.50 mol/l, why is it that the OH- concentration is 1.50x10^(-14) mol/l? When they are multiplied together, it does not equal the water constant (1.0 x10^-14). Thank you!

Michael Du 1E

Is there an explanation as to why the constant of water is so small? (kw = 1x10^-14), thank you!

Michael Du 1E

I would say consider both the K constant and initial concentrations because you used both pieces of information in order to figure your answer. Sig figs are determined by all the numbers you used in a problem. That's what I initially thought too but there were some problems where the k had 2 sig fi...

Michael Du 1E

When we are asked to find the equilibrium concentrations and are given the initial concentrations and K constant, would our equilibrium concentrations follow the significant figures of the initial concentrations or the K?

Michael Du 1E

Recall that in the formula for the equilibrium constant, we put in the concentration of each substance to the power of their coefficient. Consider also that when summing reactions, the product of one reaction is the reactant in the next. Thus, when we multiply K for these reactions, the product-tur...

Michael Du 1E

Is there an explanation as to why the K's are multiplied when adding two reactions together to form one? Thank you.

Michael Du 1E

The reaction quotient is often asked for when the reaction is NOT YET at equilibrium. You will often need to solve for it when the problem states that there is an "initial concentration of ...", implying that it is not in equilibrium. Solving for Q is the same as solving for K and it is es...

Michael Du 1E

You do not have to convert to concentration as the provided equilibrium constant is of partial pressures (Kp). "Bars" is a pressure unit so you can simply just plug in 65 bars to all of the molecules. The work should be (65)^2/(65)^2(65) and the answer would be 1.54 x 10^-2 in which is les...

Michael Du 1E

Dr. Lavelle mentioned today in lecture that a more stabilized molecule would have more concentration and a higher k value as a result. Can anyone please explain this to me? Thank you

Michael Du 1E

GFolk_1D wrote:So would anything between k > 10^3 and k > 1 be only slight favoring?

Yea, I would assume so

Michael Du 1E

So you can use either one^

Michael Du 1E

How would you guys go about this problem? I believe it is asking for the k constant of concentration, I converted the units, etc., solved for concentration with the ideal gas law equation and wanted to know what you guys did. Thank you! "You are studying the following unbalanced reaction at hig...

Michael Du 1E

Hopefully what I say helps but from the video modules that he sent to us on his website, he mentioned how if k > 10^3, it means that the equilibrium STRONGLY favors the products meanwhile if k > 1, it favors the products too but only SLIGHTLY. But one thing that they have in common is that they favo...

Michael Du 1E

In today's lecture, for the last past exam question that we went over, can anyone please explain again why the H was bonded to the O atom instead of the Cl atom? (molecule is HClO3) Thank you!

Michael Du 1E

What is the explanation behind the fact that the conjugate base of a strong acid is neutral, while the conjugate base of a weak acid is a stronger base (basic)? Thank you!

Michael Du 1E

Quick question upon oxoacids/ so if an oxoacid has an atom that has a strong or high electron-withdrawing ability, it makes the acid more stable as it removes some of the negative charges from an atom. Does this stability result in a stronger acid or weaker acid? Thank you!

Michael Du 1E

Why is it that the H is attached to one of the O atoms and not the Cl atom despite it being the central atom? Thank you!

Michael Du 1E

how can I determine which is the stronger base of BrO- or morphine (C17H19O3N)? Thank you!

Michael Du 1E

How can we determine if a certain molecule is a strong base? For example, why is is Na(OH) considered a strong base? is there a like a certain rule, thank you!

Michael Du 1E

Is the reasoning behind HCl, HBr, etc. being a strong acid is that its anion is stable? if not whats the particular reasoning behind why they are strong acids? thank you!

Michael Du 1E

In the lecture, Professor Lavelle mentioned that Cl- in NH4+Cl- does not affect the ph and therefore we leave it out. Can someone explain how and why the Cl- does not affect the pH?

Michael Du 1E

BF3 is a lewis acid as if you draw out the lewis structure of it, it only has 3 shared bonds with no lone pairs, having a total of 6 electrons. However, this does not complete the octet rule so it is willing to accept an electron pair which is defined as a lewis acid.

Michael Du 1E

Ag+ would only have 6 valence electrons in the outer shell. It would want to complete its octet so it would want to be an electron pair acceptor which is defined as a lewis acid.

Michael Du 1E

Yes! I got the same equations as you

Michael Du 1E

Why does HCO3^- act as a base, receiving a proton from water?

Michael Du 1E

Ka is given when there is a weak acid and is the acid dissociation constant. Since its a weak acid, the whole thing does not "fall" apart and we are given a dissociation constant as a result. Meanwhile, pKa is used to simply solve for the pH to determine its acidity on the ph scale.

Michael Du 1E

Only b would be able to form a chelate structures. Chelate structures are formed through bonds from the ligands and a transition metal, creating a ring like structure. Imagine a transition metal that comes into play between the H2N atoms. Both of the H2N atoms would share its electrons with the tran...

Michael Du 1E

Edta has 6 potential binding sites to bind to a transition metal, as it is a hexadentate. I would assume that these binding sites would count as one individual bond, having a total of 6 bonds and 6 as the coordination number as a result. Not too sure if I am correct.

Michael Du 1E

What charge does an Oxalato (OX) have?

Michael Du 1E

In a chelate, how does a ligand form a ring of atoms?

Michael Du 1E

In the notes, I have a quick question ligand binds. For example, if a ligand binds at 1 site it would be a monodentate. What exactly does a site refer to? thank you!

Michael Du 1E

According to my notes, these species are electron rich, replacing the H20 ligands, which is an easy way to make coordination compounds. I'm not too positively sure if the main reason is that the species are electon rich. There may be other factors to it that he did not discuss in class.

Michael Du 1E

According to the solution manual of E15, a seesaw would have an approximate angle of 90 and 120 degrees. Wouldn't the angles be less than 90 and 120 due to the lone pair causing a smaller angle than the typical angles of an electron arrangement of a trigonal bipyramidal?

Michael Du 1E

If I'm correct, polar dipoles will only cancel if they are on the opposite side of one another right? However, they will not cancel if the dipoles are adjacent to one another?

Michael Du 1E

From class, a bent example was shown through 2 lone pairs and 2 bound atoms of a central atom. Can a bent also occur from one lone pair and 2 bound atoms? if so, would the bond angle be the same or different?

Michael Du 1E

I remember Professor Lavelle mentioning how there could be two tetrahedrals of two different molecules (same central atom but different outside atoms attached to it) and that one of them would have a slightly lower bond angle due to the atom's size or electronegativity from what I recall. How would ...

Michael Du 1E

Are we expected to know the exact bond angles on the test? Or just naming the shape of the molecule. Thank you!

Michael Du 1E

Ruby Richter 4G wrote:Just for clarification, how exactly does an atom having an incomplete octet make it more stable?

You can check the formal charge of the atom with the incomplete octet, and it would have a formal charge of 0, meaning it didn't gain or lose any electrons, making it stable. Hope this helps!

Michael Du 1E

How come diethyl ether does not have a H-bond in it like butanol?

Michael Du 1E

What is the explanation behind a bigger size of atom would result in a lower interaction potential energy?

Michael Du 1E

From the lecture, can anyone please explain to me why F2 and Cl2 are gases at room temp. while Br2 is liquid and I2 is a solid? Thank you.

Michael Du 1E

How do we know if a lewis structure or molecule has a van der waal intermolecular force? What do we look at?

Michael Du 1E

What is the explanation behind why single bonds have longer bond lengths than double and triple bonds?

Michael Du 1E

Why is it that in some problems or molecules, the central atom doesn't follow the lower ionization rule? Say for example, CH3Br, I would assume Br would be the central atom since Br has a lower ionization energy as it has a larger radius. However, C would be the central atom rather than Br. thank you.

Michael Du 1E

I have a question upon the order of the electron configuration. Say for example for copper the configuration would end with 3d^9 and 4s^2 coming after. When the 4s donates an electron to 3d to make it fully stable, would the 4s^1 now come before the 3d^10 when writing down the configuration? Thank y...

Michael Du 1E

When a problem asks to draw the lewis structure of a molecule, are we expected to draw the one with the lowest energy or only when the problem says to?

Michael Du 1E

On the midterm, are we expected to write the formal charges on the lewis structure even if the problem does not ask for the formal charges?

Michael Du 1E

Adding to Daniel, you would use the De broglie equation when the velocity of some particle or so is given. The other equations have no correlation with velocity in it and you would think about using them when trying to solve for frequency or so.

Michael Du 1E

This is what I was wondering too, I was thinking about that process in which after converting to Kg, I would then convert from mols to atom with the Avogadro's number, but I am not too positive.

Michael Du 1E

Can anyone please explain to me how bonds can potentially have both ionic and covalent character? thank you.

Michael Du 1E

Check out the example in the textbook reading. I also struggled on this at first, but I was able to understand how to do it a bit more after I looked at the example. In these complex compounds there's often double central atoms and I would take the initial step in finding those first.

Michael Du 1E

Despite Cl having a lower ionization energy than C, why is C still the central atom and not Cl? (Formula is CCl4) thank you.

Michael Du 1E

For the homework problem of 1E 13 e, the solution is [Xe] 4f^14 5d^4 6s^2. Why don't we transfer an electron from the 6s orbital to the 5d orbital to make it half full? thank you.

Michael Du 1E

In the homework problem, for 2A c, why are the 5 electrons in the 3d orbital included with the 2 valence electrons of 4s? (having a total of 7 valence electrons as a result). Thank you

Michael Du 1E

Referring to how atoms and ions having the same number of electrons, the chemistry, bonding, structure will be different as mentioned above. Part of the reason is that despite that atoms and ions having the same number of electrons, they will have a different amount of protons from one another.

Michael Du 1E

When doing the electron configuration for any atom, and making it stable, why can't I move an electron from an S orbital to a p orbital like how we do with an electron from the s orbital to the d orbital?

Michael Du 1E

This is due to the Hund's rule in which there is e- repulsion, where electrons in the same sub-shell can only occupy different orbitals with parallel spin. From this, we will get the lowest energy which is what we want to obtain the ground state of an atom.

Michael Du 1E

Can explain please explain to me the effective nuclear charge? thank you. I'm not really understanding what it is.

Michael Du 1E

Adding on to Ashley, the orbitals can also be interpreted as regions of probability where an electron can be found rather than just simply shapes as introduced in high school.

Michael Du 1E

According to the solution manual error in Professor Lavelle's website, there was an error for the answer in the solution manual and the actual answer is a transition from n=3 to n=1 as it is emitting. Wouldn't this contradict the concept that n initial would be 1 due to the Lyman series? With the ac...

Michael Du 1E

In the problem, the given information of the velocity is 5.00 (+-) 5.0 m/s. If this is the case, the interval of the velocity would be 0-10 m/s and the uncertainty of the velocity would be 10 m/s, if I'm correct. However, in the solution manual, it states that the uncertainty of the velocity is 5.0 ...

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