CHEMISTRY COMMUNITY

ellenulitsky Dis 1I

This is how I did #15! Hope this helps!!

ellenulitsky Dis 1I

This is how I did it! Hope this helps!!

ellenulitsky Dis 1I

This is how I did it! Hope this helps!!

ellenulitsky Dis 1I

Here is how I did it! Hope this helps!

ellenulitsky Dis 1I

Here is how I did it! Hope this helps.

ellenulitsky Dis 1I

I really like Khan Academy!

ellenulitsky Dis 1I

I had trouble balancing as well and I just watched a youtube video on how to do it and just did a bunch of practice problems. Hope this helps!

ellenulitsky Dis 1I

You add when they are state properties, but since K or Q arent, then you cannot just add, it is more complicated than that since the path taken MATTERS. Hope this helps!

ellenulitsky Dis 1I

And you just tell if it is either of the three orders by looking at the graph and seeing which type of graph it is?

ellenulitsky Dis 1I

No, they aren't always at equilibrium, as they create a voltage when reaching equilibrium.

ellenulitsky Dis 1I

Remember that the standard cell potential is zero for S.H.E! Hope this helps.

ellenulitsky Dis 1I

Make sure your zeros are not Os because that is what got me stuck. Hope this helps!!

ellenulitsky Dis 1I

Hi, this is how I was able to solve it! Hope this helps!

ellenulitsky Dis 1I

I had a different reaction than you but this is what I did for question 3. Hope this helps!

ellenulitsky Dis 1I

You are very close. The answer is 4Fe+3O2+6H2O⟶2Fe2O3∙3H2O. Hope this helps!!

ellenulitsky Dis 1I

You first have to convert J/s to J/Hr and then divide (J/Hr)/(Degree in C + 273K) to get the units J/K*Hr. Hope this helps!

ellenulitsky Dis 1I

I had this same question too and was told it's only gases, not aqueous solutions too.

ellenulitsky Dis 1I

How I like to think about this is that it is a battery and there is an exchange of electrons, and, therefore this movement of electrons is electricity. Hope this helps!

ellenulitsky Dis 1I

I was wondering the same thing! I'm not sure if we need to know this or not.

ellenulitsky Dis 1I

Molecules that are polar have entropy! Hope this helps.

ellenulitsky Dis 1I

Make sure you convert the 57.91 J·mol−1·K−1 to kJ/mol*k and then plug it into the T=deltaH/deltaS equation to solve to T. Then since the answer is in K, you have to subtract 273K to get the final answer in Celsius. Hope this helps!

ellenulitsky Dis 1I

I would use what is on the constants sheet to be safe! Hope this helps!

ellenulitsky Dis 1I

How I thought about it is that there are two things happening, the first is a change in volume and also a temperature change. The total entropy is equal to Sv+St. Hope this helps!

ellenulitsky Dis 1I

Remember that Q=[products]^coefficient/[reactants][reactants]^coefficient. And then use the equation deltaG=RTlnQ+deltaGstandard! Hope this helps. Also, watch out for the units.

ellenulitsky Dis 1I

You know that deltaE is equal to q-w(w is neg bc work out of system). You then convert kcal to kJ to find q, then you do q-w(which is what was given to you). Hope this helps!

ellenulitsky Dis 1I

Yes, I assumed that when he said O2, he also meant that other diatomic particles would approach zero since there are 2 identical elements and there cannot be a lot of variations in their reactions. Hope this helps!

ellenulitsky Dis 1I

I was wondering the same thing because when I looked it up online it said "Negative heat capacity would mean that when a system loses energy, its temperature decreases", so it is possible? I'm not really sure if that is the correct answer though!

ellenulitsky Dis 1I

Yes, I think it can be both! It just depends on what the system is and what is happening. Hope this helps!

ellenulitsky Dis 1I

I just look at the units and see what matches up with it from the constant sheet given to us! Hope this helps.

ellenulitsky Dis 1I

I think the rest of the quarter will be on thermodynamics(so thermochemistry included) since that is the main topic we are covering in 14b. Hope this helps!

ellenulitsky Dis 1I

Only gas and aqueous entities affect K. Liquids and Solids do not. Hope this helps.

ellenulitsky Dis 1I

It is the 5% rule, which is the same method as finding percent ionization! Hope this helps!

ellenulitsky Dis 1I

Use the 5% rule which is the same way of doing percent ionization! Hope this helps!

ellenulitsky Dis 1I

Since you need to know the concentration which is mol/liters, it will be .0025mol/.1L which is 0.025M. as the concentration of [Ba(OH2)] and [Ba+], the concentration of [OH-] is 2*.025M since there are two [OH-]. Hope this helps!

ellenulitsky Dis 1I

Yes, they are the same thing and are used interchangeably! Hope this helps.

ellenulitsky Dis 1I

An example of a state property is delta H, as it doesn't depend on the path to get this change, but rather the initial and final. Hope this helps!

ellenulitsky Dis 1I

Yes, so even though there is heat being added, the temperature does not change since the heat added is breaking the bonds. Hope this helps!

ellenulitsky Dis 1I

It is called the "5% rule" where it is (concentration you found/given)*100% (has to be less than 5% in order to use the assumption), which is the same process as finding the percent ionization. Hope this helps!

ellenulitsky Dis 1I

A lower pKb value indicates a stronger base! Hope this helps!

ellenulitsky Dis 1I

They are added together. The examples we had in sapling added together 1/K or K^2 to show how if you reverse the reaction or double its moles then it still be added all together, but in a trickier way! Hope this helps.

ellenulitsky Dis 1I

K is the equilibrium constant and is present at equilibrium. However, when solving for Q, it can be happening at any point, hence why it can be greater, less, or equal to K. If it is less or greater than K then you know it is NOT at equilibrium yet. Hope this helps!

ellenulitsky Dis 1I

How I like to think about it is that if it is aA+bB<---->cC+dD then it is Kc, if it is cC+dD<---->aA+bB then it is 1/Kc (this is the inverse). Hope this helps!

ellenulitsky Dis 1I

I believe that if the temperature is not 25 degrees Celsius then the Kw is not 10^-14. Hope this helps!

ellenulitsky Dis 1I

How I like to think about it if when plugging in the two positive x concentrations into the actual concentration of a molecule, if it is negative then that does not make sense and therefore you will be needing to use the one that makes a positive concentration since concentration cannot be negative....

ellenulitsky Dis 1I

Using ICE tables are applicable to both partial pressures and concentrations as you use Kp and Kc the same way([products]/[reactions]). Hope this helps!

ellenulitsky Dis 1I

I feel as though the TAs will be looking for posts made in 2021 so that it is fair throughout the class! Hope this helps.

ellenulitsky Dis 1I

Is an ICE table to only way to solve questions when missing one of the concentration values?

ellenulitsky Dis 1I

Yes, I did some research and found that the K value of pure water at 25*C is 1x10^-14! Hope this helps.

ellenulitsky Dis 1I

You will always be using Kelvin since when looking at the other units in PV=nRT, there is only kelvin being used, so if using celsius for example, the units will not cancel out. Hope this helps!

ellenulitsky Dis 1I

Molarity is given by doing (mol/volume). n is the number of moles, while V stands for volume so by doing n/V, it gives molarity, which is equivalent to the concentration(why we include molarity inside [] not only moles! Hope this helps!

ellenulitsky Dis 1I

H-bonding is a type of intermolecular force and is the strongest intermolecular force out of D-D and LDF, therefore when a molecule is present in water(ie. intermolecular forces are between two molecules), it is the hardest to break, and therefore has a higher boiling point. Hope this helps!

ellenulitsky Dis 1I

O2- is a very strongly basic anion due to its very small size and high charge. Hope this helps!

ellenulitsky Dis 1I

Yes, I just think that a pair of electrons, a single bond, double bond, and triple bond are each just ONE region of electron density.

ellenulitsky Dis 1I

I drew out the different orbitals to help me with this problem! Hope this helps!

ellenulitsky Dis 1I

I drew out the different orbitals to help me with this problem! Hope this helps (sorry that it is a little messy)

ellenulitsky Dis 1I

N2H4 makes the trigonal pyramidal shape, which should have an angle of <109.5 degrees, however in the answer key, it says that the angle is 107 degrees. How should we know the exact degrees for this molecule? Thank you!

ellenulitsky Dis 1I

I just had the discussion section and I think my TA said something similar to Table 9C.1 would be provided(which gives common ligands and their formulas). Please correct me if I'm wrong. Hope this helps!

ellenulitsky Dis 1I

Do the TEXTBOOK problems, especially since Dr, Lavelle wrote that in the document with the description about the final.

ellenulitsky Dis 1I

Yes, so the charge of the total oxygen atoms would be -8 since there are 4 oxygens, each with a -2 charge. Hope this helps!

ellenulitsky Dis 1I

This helped me a lot to understand the differences between the types of ligands. Hope this helps!

ellenulitsky Dis 1I

I think we use ferrate for coordination compounds. Hope that helps!

ellenulitsky Dis 1I

How I like to think about it is if it is an odd number of bonds attached to the central atom (ex. 3) and the central atom can have a full octet, then usually it has resonance. Resonance in terms of the bond strength is the average of the different identical ways of making the lewis structure. Hope t...

ellenulitsky Dis 1I

To add to the posts above, a triple bond is more stable than a double, and then a double bond is more stable than a single bond. Hope this helps!

ellenulitsky Dis 1I

Yes, I also agree that Dr. Lavelle does not expect us to know how to calculate EN. Just know the trends of EN! Hope this helps.

ellenulitsky Dis 1I

H2O has an AX2E general formula, which is a bent shape! Hope that helps.

ellenulitsky Dis 1I

I think since it is Li^+ and O^2-, I would assume it comes from the oxygen since the overall charge of Li2CO3 is zero! Hope that helps.

ellenulitsky Dis 1I

When doing this problem, the biggest thing to remember is how in CO3^2- it has resonance meaning the double bond and 2 single bonds average out, making it still longer than the CO2 and CO! Which makes it easier to understand how to rank the molecules. Hope that helps!

ellenulitsky Dis 1I

Yes! How I like to think about it is that the molecules that have higher BP and MP are "stronger"(they can withstand dramatic temperatures) than molecules that have lower BP and MP. Hope that helps!

ellenulitsky Dis 1I

I also agree that that is correct! Also, I like to look at the periodic table and know that for that column, the charge is 2-, because then it gets to that full octet! Hope that helps.

ellenulitsky Dis 1I

Also remember that Hydrogen bonding is a type of intermolecular force, which means that if it is given only one molecule, you have to assume that it H-bonds with another identical molecule, so now there are two identical molecules in play! Hope that helps!

ellenulitsky Dis 1I

How come Ba-Br has a greater EN difference than Be-Br? Since EN increases when going up the periodic table, I am thinking that Be has a greater EN and therefore a bigger EN difference between Be-Br, but that is incorrect since the textbook says that the EN difference is greater for Ba-Br.

ellenulitsky Dis 1I

Yes, that looks correct. Since losing three electrons is easier than gaining 5, it seems as though it will be Ga+3. Hope this helps!

ellenulitsky Dis 1I

So the M2+ ions (where M is a metal) makes it very simple to find since you take away from the 4s2, however when it is M3+ ions (where M is a metal), you have to take away 4s2 and 3d1. Hope this helps!

ellenulitsky Dis 1I

When looking at boiling points or melting points, you want to be using INTERmolecular forces NOT INTRAmolecular forces. This helped me a lot when figuring out how to solve this type of problem. Hope this helps!

ellenulitsky Dis 1I

Yes, since when drawing the lewis structures, the most accurate ones are the ones that are the most stable. The closes to zero the lewis structure are the more stable it is! Hope this helps!

ellenulitsky Dis 1I

How come in the molecule, BCl3, boron does not follow the octet rule(ie. it has 6 shared electrons, not 8). I thought the only exceptions are H, He, Li, and Be. Thanks!

ellenulitsky Dis 1I

Yes, your reasoning is correct because they can only hold a maximum of two electrons in its valence level, which defies the octet rule! Hope this helps.

ellenulitsky Dis 1I

When finding the charge of the lewis dot structure, I first find the charge of each individual atom and then add up the charges to find the total charge! Hope this helps.

ellenulitsky Dis 1I

Since this is general chemistry, I believe that most ionic compounds that will be given to us include Na+. And the reason Na+ makes an ionic compound is since the bonds formed between two ions of opposite charge makes it an ionic compound. Hope this helps!

ellenulitsky Dis 1I

I think molecules with multiple resonance structures will be more stable than one with fewer resonance structures and some resonance structures contribute more to the stability of the molecule than others (ie. formal charges aid in determining this). So you are correct! Hope this helps.

ellenulitsky Dis 1I

The oxidation number of a free element is always 0 and the oxidation number of a monatomic ion equals the charge of the ion, which is found in the periodic table.

ellenulitsky Dis 1I

I don't think we need to know the difference between a ring and a chain bc that is more organic chemistry.

ellenulitsky Dis 1I

^^^ yes I believe so since diffraction patterns are caused by waves! Hope this helps.

ellenulitsky Dis 1I

I was going to ask this question on chemistry community too! All I know is that oxygen has lower ionization energy than fluorine, as fluorine is farther to the right on the periodic table and follows the trend that IE increases as you go right. However, the anomaly is that oxygen has lower ionizatio...

ellenulitsky Dis 1I

This diagram helps me understand the trends in the periodic table and how they interplay with each other! Hope this helps!

ellenulitsky Dis 1I

Yes, that is what I also got from the lectures. It makes sense because if you see that electrons have been "moved" to a higher orbital before filling the lower orbital, then that atom is in an excited state, which would be different than the ground-state electron configuration.

ellenulitsky Dis 1I

I ended with phosphorous too! So I think it is the correct reasoning!

ellenulitsky Dis 1I

We use the periodic table that Dr. Lavelle provides us on his website! It is next to the equation sheet that is also going to be used in the midterm! Hope this helps.

ellenulitsky Dis 1I

I usually do nm, but it all depends on what the problem is asking you to convert to. I look at the word problem and also what unit the multiple-choice options are in! Hope this helps!

ellenulitsky Dis 1I

How I like to think about it is if the uncertainty is 10Å, then it is just 10 x10^-10 m, while if it gives you +/-10Å, it will be 10x10^-10 m in the positive direction and 10x10^-10 m in the negative direction as the uncertainty. Hope this helps!

ellenulitsky Dis 1I

Yes, I noticed that problem too in the module. In the lecture, there was a problem where something was greater than the speed of light(which is impossible) and it was clearly stated that this isn't logical. So I would definitely use logic over the answer you get! Hope this helps.

ellenulitsky Dis 1I

I was confused by that too! So you multiply it by 2 so that it can be within the entire spectrum of uncertainty, which accounts for the positive or negative uncertainty?

ellenulitsky Dis 1I

They were surprised that this diffraction pattern of the waves worked on a substance like crystal(ie. table salt) and what was flowing like a wave was the photons.

ellenulitsky Dis 1I

T/F, An increase in intensity means an increase in energy?

I am not sure what the answer to this is.

ellenulitsky Dis 1I

I think there will be a step up session that will have a practice midterm. That's all I know so far though :/

ellenulitsky Dis 1I

My phone and Ipad worked well for this! Hope this helps!

ellenulitsky Dis 1I

To answer the multiple-choice question, the answer is electron diffraction (B). During Friday's lecture, Dr. Lavelle showed us that electrons have wave properties by visualizing the two types of diffraction patterns, constructive (waves in-phase) and destructive interference (waves out of phase). Th...

ellenulitsky Dis 1I

In the diagram that I posted above, it shows how the Balmer series is in the infrared region, while the Laymen series is in the UV region. The infrared region has less energy as it has a longer wavelength then the UV region which has a shorter wavelength and thus making it have a higher energy. This...

ellenulitsky Dis 1I

Hi, here is a diagram Dr. Lavelle showed us in his lecture on Wednesday. This really helped me understand how the energy levels relate to the two different types of series.

ellenulitsky Dis 1I

I think most of the Sun's light is in the infrared, visible, and ultraviolet parts of the electromagnetic spectrum but it emits shorter wavelengths like UV rays.

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