CHEMISTRY COMMUNITY

Tiffany_Cacy_3D

I believe it just speeds up the overall reaction, both forward and backwards. If this is the case then the amount of reactants and products being formed shouldn't change.

Tiffany_Cacy_3D

Positive standard cell potential correlates to K>1 because of the equation Delta G=-nFE. This shows that whenever E is positive, Delta G will be negative (moles are never negative and F is a positive constant). When Delta G is negative this means the reaction will be spontaneous and will favor produ...

Tiffany_Cacy_3D

I did the same exact thing and got the same answer. I think as long as everything cancels out correctly it should be the same. On the test there will only be a certain number of reactions to choose from as well so I think it will be more clear which reactions we are supposed to use.

Tiffany_Cacy_3D

How do you tell which step in a multistep reaction is the slow step? Would we be given this information or is there a way to tell by the step itself? I am having trouble figuring out which step is the rate limiting step.

Tiffany_Cacy_3D

Hello, it has been a while since we took test two but I am still really confused about one of the problems. I am sure it varied slightly for other people but a brief outline of how to do this problem would be really helpful. The question was.... 5. The ionic dissociation of water us given by the fol...

Tiffany_Cacy_3D

This is our last out of ten. We don't need to turn in an extra 7 because finals week doesn't technically count towards the quarter.

Tiffany_Cacy_3D

It is probably a good idea to know what these look like just because that knowledge could potentially help you figure out which order a reaction is. It is a useful way to test the order of a reaction.

Tiffany_Cacy_3D

I would say so. My TA went over a past exam question today which asked for the rate law given a table of reactants and concentrations. It would be a good idea to study this sort of thing as the concept will surely come up even if it's not in that specific form.

Tiffany_Cacy_3D

The order is generally the sum of the exponents of each concentration contributing to the rate law. This information not only helps you calculate the rate law, it gives you a clearer understanding about the mixture and which concentrations effect the rate of the reaction the most.

Tiffany_Cacy_3D

The double >> just means that it is very favorable, it is just a way to express that it is strongly favored.

Tiffany_Cacy_3D

Delta G is 0 at equilibrium because the forward and the backward reactions are equivalent which would mean they cancel each other out.

Tiffany_Cacy_3D

I was wondering the same thing, there doesn't seem to be an actual trend that you can just look at or infer. I think you may actually just need the values to evaluate them.

Tiffany_Cacy_3D

No just like how you add and subtract the electrons that you include in the half reactions you can cancel out H20 in that situation as well.

Tiffany_Cacy_3D

Is the reverse given? I couldn't find the values anywhere, I wasn't sure if you are maybe supposed to derive them from the ones that are given? I am not sure how to go about that though.

Tiffany_Cacy_3D

So in the 7th edition in section 6M there are several questions including 6M.3. which ask you to predict the standard potential of different galvanic cells. In the book there is a tabel containing many of the E/V values which you use plug into the formula Ecell=E(cathode)-E(anode) but in some cases ...

Tiffany_Cacy_3D

Yes they will be as long as it is a forward reaction because nothing would be reduced or oxidized before a reaction even happens. The oxidizing agent would become the reduced product and the reducing agent would become the oxidized product.

Tiffany_Cacy_3D

When constructing your cell diagram I know that the anode portion goes on the left of the salt bridge and the cathode goes on the right but within those limits does the order of the species matter? For example if the anode half reaction is H2(g) --> 2H+(aq) + 2e- would it matter when you are drawing...

Tiffany_Cacy_3D

Hello, I am trying to plan my classes for next quarter and as of right now I am planning on taking Math 3C and Chem 14C for sure. For the sake of units I need to take a GE as well and I was thinking of maybe taking 14BL also. I know 14BL is only worth three units but does anyone know how time consum...

Tiffany_Cacy_3D

Yes we still have homework due regardless of the midterm.

Tiffany_Cacy_3D

" During the test of an internal combustion engine, 3.00L of nitrogen gas at 18.5 degrees C was compressed suddenly (and irreversibly) to .500L by driving in a piston. In the process the temperature of the gas increased to 28.1 degrees C. Assume ideal behavior and 1.00 mole of nitrogen gas. Wha...

Tiffany_Cacy_3D

I noticed that a couple problems in the book ask you to "assume ideal behavior". After looking at the solutions manual it looks like this means assume there is 1 mole of the given substance? I am not familiar with this phrase and I am hoping someone can maybe shed some light on the subject.

Tiffany_Cacy_3D

When work is done by the system the value you are going to get will be negative and when work is done on the system the value you will get will be positive. You shouldn't really have to worry about whether or not to put a negative because the determining sign will be a part of your equation you use....

Tiffany_Cacy_3D

Although the both of these seem to be changing at the same time we treat them as though they happen separately. So when calculating volume you act as though your temperature is a constant and when you calculate the temperature you do the same thing. We can take the entropies separately and then add ...

Tiffany_Cacy_3D

If you are referring to the q=nCm(Delta T) then usually it will give you specific heat or another value for C that you can plug into the equation q=C(Delta T) or q=mCs(Delta T) if it does not give you the moles.

Tiffany_Cacy_3D

Expansion work is work dealing with pressure-volume while non expansion work is pretty much everything else. I believe Gibbs helps you find the maximum amount of non expansion work that can potentially be done, but I am not sure how this relates to reversibility so hopefully someone else can answer ...

Tiffany_Cacy_3D

How do we find the enthalpy for a complicated molecule? I know some of them are listed in the book but are we expected to figure out complicated enthalpies during a test or will those generally be given?

Tiffany_Cacy_3D

I am pretty sure that we don't get the lewis structure because my TA broke the process of calculating this down in steps and one of the first steps was to draw out the lewis structures to make sure that we account for all of the bonds.

Tiffany_Cacy_3D

In both of these the number of particles is fixed and there is no exchange with outside systems in either of them. I am pretty sure the only difference is that a closed system can have a fluctuation in energy but the isolated system cannot. Could anyone explain why? I am still confused how that is a...

Tiffany_Cacy_3D

Just as with any other problem it is good to have more than one way to solve it. That being said, the information you are given will dictate which one of the three options you can or cannot use. For example if you are only given the total Delta H of the reactions you would have to use the first meth...

Tiffany_Cacy_3D

In my notes from lecture on January 25th I wrote that bond enthalpies of diatomic molecules are accurate but other bond enthalpies are not as accurate and I was wondering why? I didn't write an explanation so I was struggling to make sense of what this means.

Tiffany_Cacy_3D

I believe this rule is actually anything below 10 to the -3 not -5 so if you had a number to the -4 you should be alright to leave it out. I am not 100% sure that is correct but the 5% rule at the end will always let you know if it was okay to round it a bit.

Tiffany_Cacy_3D

During the last bit of class we talked about exo- and endothermic reactions and how this is determined by delta H. What is delta H and if it is positive does that mean it is always going to endothermic and favor the products when heat is added? If it is negative does it always mean it is exothermic ...

Tiffany_Cacy_3D

Would the products or the reactants be favored when volume of a system is compressed if there was an equal number of moles on both sides? What else would determine which is favored if not the number of moles?

Tiffany_Cacy_3D

Thank you that is actually very helpful!

Tiffany_Cacy_3D

In class the example we did for ice tables involved the equation H2o + ATP = ADP +P. When finding the solutions we found that the change in molarity for ATP was about -8.435 so in turn we added 8.435 to both ADP and P. Do we add the same amount to both because there is a 1-1 ratio between them or wo...

Tiffany_Cacy_3D

I am not sure I can explain as in depth as you are looking for, but I believe Charle's law describes how gasses expand when they are heated up. Basically the experiment showed that when pressure is constant, the volume of the gas will be directly proportional to the temperature of the gas (in Kelvin).

Tiffany_Cacy_3D

So if you have a chemical equation that you want to find the equilibrium constant for, you do not include solids or liquids at all? I understand that this means that you do not include them in the K equation but if they are a part of the reaction shouldn't they affect the equilibrium? I am just a li...

Tiffany_Cacy_3D

Just to be clear we only need to conceptually understand Ka and Kp values and equilibrium constants but we do not actually have to solve for this or use these factors for anything except determining which acid or base is stronger?

Tiffany_Cacy_3D

Usually this value is given to you as the molarity of the solution or you are given moles and volume of a certain solution and you have to find the molarity by dividing moles of solute by liters of solution to find the molarity to in turn plug into the pH equation.

Tiffany_Cacy_3D

If you draw the lewis structure for (SO4)2- with only single bonds it would not have an expanded octet but in order to draw the lewis structure with the least amount of formal charges you have to draw the lewis structure with two single bonds and two double bonds so that only two Oxygens have negati...

Tiffany_Cacy_3D

Those rules are only applicable in certain situations. When you have the case where you're looking at two acids that they all have the same configurations such as ClOH, BrOH, and IOH you can't look at the atomic radius because the hydrogens are not directly attached to the differing atoms. In this c...

Tiffany_Cacy_3D

I don't fully understand why SO3 is the base but when I draw the lewis structure you can see that there is resonance in its structure and in order to fill the octet rule the Sulfur in the center has to make one double bond. When you draw the lewis structure for H2O2 it is nicely balanced, it is non-...

Tiffany_Cacy_3D

A ligand is polydentate if it has more than one place where it is binding to a central metal atom. An example of this would be EDTA, which binds to a metal in six different places, also known as a hexadentate ligand.

Tiffany_Cacy_3D

I know that ligands are molecules that bind to a central atom but I am a little confused on what the difference is between a regular ligand and a chelating ligand. Also can ligands ever have double or triple bonds or are they strictly single? I have only seen single bonds so I was curious if they wo...

Tiffany_Cacy_3D

So i know several elements can act as both an acid and a base such as water but how do you tell when a water should act as an acid or a base. When do you know when it should give up or accept electrons? Also does water affect the likelihood of certain compounds being stronger or weaker acids or bases?

Tiffany_Cacy_3D

If it does completely dissociate in water how do you actually tell when this happens? Is there a way to tell how much it will dissociate?

Tiffany_Cacy_3D

I believe we are just supposed to know the different trends that occur as more and more lone pairs are presented on certain types of molecules. This would include the two you have listed above as well as linear, see saw, trigonal bi-pyramidal, t-shaped, among others as the molecules get bigger and b...

Tiffany_Cacy_3D

While Fluorine is a very electronegative atoms, this electronegativity creates very strong Intramolecular bonds which make the molecule itself very hard to break apart. When you are talking about boiling point however the bonds between molecules, or the intermolecular bonds, are what you actually ne...

Tiffany_Cacy_3D

When you are trying to decide wether a molecule is an acid or a base is there more ways to determine this other than if the molecule donates or accepts electrons? I know there are some other indicators but what are they and are they as accurate as looking at whether they receive or donate electrons?

Tiffany_Cacy_3D

Bent molecules actually do not have a bond angle of 109.5 degrees because the lone pairs are more electronegative and push the other atoms more closely together. This would cause the bond angle of a bent molecule to be less than 109.5, the exact value i believe was 104.5 degrees. I think the only mo...

Tiffany_Cacy_3D

I am a little bit confused about what a dipole actually is. When we were talking about interactions in lecture and ion-ion, ion-dipole, and dipole-dipole reactions were brought up how do you determine whether something is a dipole or not?

Tiffany_Cacy_3D

So when considering the shape of a molecule it helps to first look at how many electrons are going to be connected to the central atom. The difference between a trigonal planar and a trigonal pyramidal is the planar has a total of three things connected to the central atom while the pyramidal has fo...

Tiffany_Cacy_3D

In that instance you would have to consider a 3D model instead of a 2D model. The surrounding atoms want to be as far away from each other as possible so a three dimensional model provides the most space between the atoms.

Tiffany_Cacy_3D

Group 13 elements only have three electrons available to make bonds. They can only accept three more because once they have six there are no more electrons available to bond with.

Tiffany_Cacy_3D

So when you're writing out the electron configuration for an element such as Bromine would you write this as 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{5} or would you switch the 3d^{10} and 4s^{2} orbitals. I am not sure when to write the d orbital before the s or if I should always writ...

Tiffany_Cacy_3D

So i know that sometimes you can have ten electrons in the valence shell by using the d orbital but is there ever a time when you have even more in the valence shell? Do you ever use the f orbital to accommodate more electrons?

Tiffany_Cacy_3D

On the class website there are lists of everything you need to know for each subject. The midterm covers "Review of Chemical & Physical Principles", "The Quantum World", and part of "Chemical Bonds" and I don't believe those topics are listed under these subjects. T...

Tiffany_Cacy_3D

I know that electronegativity is the tendency an atom has to attract a bonding pair of electrons to itself but how do we find the electronegativity of an atom? Why is Fluorine higher than the other halogen elements? I am just a little confused on how the electronegativity trend works and why it decr...

Tiffany_Cacy_3D

How do elements actually keep their shape and the same number of electrons as they bond and detach from other elements. Is it just the magnetic pull that keep them together? Once they lose or gain electrons how do they regain or get rid of them after?

Tiffany_Cacy_3D

When you have an example like the one that professor went over during lecture with 2 cations and 1 anion where do they bond together if they all have full valence shells? I believe the example was ammonium sulfate (NH4)2+ (SO4)2-

Tiffany_Cacy_3D

Argon and copper both share the exact same beginning of their electron configurations. By putting argon before the rest of the configuration it just makes it shorter to write out. These short cuts make it so that the elements with longer configurations are more easily written.

Tiffany_Cacy_3D

We went over this a little bit in our discussion week so hopefully this will help. 1)Energy of a photon: E=hv and c=v(lambda) -These are commonly used in questions concerning the photoelectric effect.These are used for photons only. 2) De Broglie's Equation: lambda=h/p(momentum) -Although this also ...

Tiffany_Cacy_3D

Is test 2 on only the the quantum world section or will there be questions on the previous section as well?

Tiffany_Cacy_3D

On Lavelle's website under "Lecture Outlines" he has a list of everything you need to know for each subject. Neither one of those subjects are on there so you won't need to know them for the chapter two test.

Tiffany_Cacy_3D

I believe the reason that this equation is negative is because all free electrons (when they are not near something) have a value of zero joules and because bound electrons have a lower energy then free electrons the bound electrons have to be less than zero (or negative).

Tiffany_Cacy_3D

In any problem where you were using the equation E=1/2(MV2) how would you find M? Is there any way you could find the mass of the actual electrons themselves if you are given what time of element it is from? Does it just have to be given in order for you to use this equation?

Tiffany_Cacy_3D

I am taking the post-module test for the photoelectric effect module and I am having trouble with number 28. So the information given is the velocity and the work and the work function. Because it is asking for the Kinetic Energy I assume you would need to use the formula E=1/2(MV2) but I am not sur...

Tiffany_Cacy_3D

21. According to the following equation, 0.750 g of C6H9Cl3 is mixed with 1.000 kg of AgNO3 in a flask of water. A white solid, AgCl, completely precipitates out. What is the mass of AgCl produced? C6H9Cl3 + 3AgNO3 ---> AgCl + C6H9(NO3)3. Molar Mass: C6H9Cl3 (187.50 g/mol), 3AgNO3 (169.88 g/mol), Ag...

Tiffany_Cacy_3D

The difference between molar mass and formula mass is that formula mass is the sum of all the atomic weights of the atoms in its empirical formula while molar mass is just the mass of 1 mol of a substance. Molar mass also uses the units g/mol while formula mass uses atomic mass units (amu).

Tiffany_Cacy_3D

I believe the only necessary materials for this course are the "Chemical Principles The Quest for Insight" (7th edition) textbook and the Student Solutions Manual that accompanies it. The textbook has a periodic table of elements on the first page and the formulas can all be found in the b...

Search found 70 matches