CHEMISTRY COMMUNITY

Mahli Martinez 2I

You can indicate this if you're given the value of the work. If the work value is negative, then work is being done by the system. If the work value is positive, then work is being done on the system.

Mahli Martinez 2I

A graph depicting a second order reaction will have a linear graph for 1/{A} vs time.

Mahli Martinez 2I

To calculate the overall order, you can just add up the order of each reactant! It's as simple as that.

Mahli Martinez 2I

The rate constant can only be changed by a change in temperature.

Mahli Martinez 2I

If there is a positive value for work, that indicates that work is being done ON the system. If there is a negative value for work, that means that work is being done BY the system.

Mahli Martinez 2I

Yes! The salt bridge does in fact allow movement, owed to the oxidation that occurs.

Mahli Martinez 2I

Le Chat's principle helps us observe how a change in temperature, concentration, or pressure/volume affects a reaction. It tells us which way the reaction will shift in response to the aforementioned change.

Mahli Martinez 2I

The spontaneity of a reaction can be figured out if you observe its value for gibbs free energy. If it has a positive value for gibbs, it's nonspontaneous. If it has a negative value, then it's spontaneous!

Mahli Martinez 2I

Hey! I definitely feel like there is more math involved in 14B than in 14A, but it's kind of similar in my experience. Doesn't feel like more or less work.

Mahli Martinez 2I

When discussing kinetics, we're referring to what's happening on a molecular level with reaction rates and and times, whereas thermodynamics allows us to discuss the spontaneity/occurrence of reactions and the changes in energy.

Mahli Martinez 2I

Work can be defined as the mechanical transfer of energy between two systems. The way you calculate work depends on a few factors.

Mahli Martinez 2I

All of the things you listed are state functions. Remember, state functions have both a final and initial state, and that is applicable to Gibb's free energy, entropy, and enthalpy.

Mahli Martinez 2I

It is crucial to distinguish between these two functions. ln has log base e while log is base 10. ln is the natural log.

Mahli Martinez 2I

The First Law of Thermodynamics states that energy can neither be created or destroyed (i.e. conservation of matter). It can be transferred, just not destroyed or made.

Mahli Martinez 2I

Hi! One thing I do is pay particular attention to charge and any changes that may occur. Remember that oxidation refers to the loss of electrons while reduction refers to the gain of electrons. With that being said, if I notice that a species goes from a +1 to +3 charge, I observe that it has a more...

Mahli Martinez 2I

Hey! A huge huge tip I found to work was switching up the locations I do work in. This may not work for everyone but it serves to refresh me and give me a change of space that invigorates me. I really like the Charles Young Library, the Bombshelter, and sometimes I even work on a random bench I find...

Mahli Martinez 2I

I pay particular attention to charges in the reaction. If I notice a molecule's charge increases, it has been oxidized. This makes sense because oxidation correlates to the loss of electrons, thereby a more positive charge.

Mahli Martinez 2I

For something to be an oxidizing agent would mean that it would be the compound gaining electrons/ being reduced. The reducing agent would be the compound losing electrons/ being oxidized in the reaction.

Mahli Martinez 2I

For something to be isothermal would refer to the temperature being constant throughout a system. Therefore, the temperature would not change.

Mahli Martinez 2I

Closed systems are only able to exchange energy with their surroundings, meanwhile isolated systems can't exchange energy or matter with their surroundings, hence them being completely isolated.

Mahli Martinez 2I

∆U=0 in an isolated system, when there is no internal energy change. There would be no changed in the work or heat by the system.

Mahli Martinez 2I

When making ice tables, one is typically looking to determine concentrations of reactants and/or products. Thus, using molarity in your table is most useful.

Mahli Martinez 2I

R is a constant value, therefore it can not change. However, the units can change

Mahli Martinez 2I

In sum, closed systems are not completely isolated but they still block the transfer of matter. In a closed system, the transfer of heat/energy can still occur. In an isolated system, the system itself is completely isolated and do not allow the transfer of matter or heat.

Mahli Martinez 2I

You would use moles when solving for molar heat capacity, and grams with specific heat capacity.

Mahli Martinez 2I

It depends on whether or not the reaction is endothermic or exothermic. If it is an endothermic reaction, the reaction will shift to the right. If it is an exothermic reaction, the reaction will shift to the left.

Mahli Martinez 2I

I think that a negative pH occurs when the molarity concentration of OH- or H+ is greater than 1.

Mahli Martinez 2I

The reason steam causes more of a burn is because steam changes phases when it comes into contact with skin. One can observe the heating curve and notice that the heat of vaporization for water is greater than that of boiling water, explaining why its burn is more severe.

Mahli Martinez 2I

Hi! If I am correct, ideal gases do not exist in real life as we know them. There are gases that share some characteristics and behave similarly, but they don't occur naturally. They can be produced in a lab.

Mahli Martinez 2I

No, for a system to be truly isolated would signify that its energy may not be altered. Nothing in an isolated system can be exchanged with its surroundings, and this includes energy.

Mahli Martinez 2I

I understand that take honestly, but think about what needs to be put into the cake for the bonds to form. Cake batter is put into an oven, heat is absorbed by the batter, and it becomes a cake. Thus, it is endothermic.

Mahli Martinez 2I

Our first midterm will be on Wednesday, February 2nd. It will be proctored via zoom and I am under the impression that we will take the midterm for whatever time coincides with your enrolled lecture time. For example, I am enrolled in Lecture 2 and will likely have to take the exam between 1:00 p.m....

Mahli Martinez 2I

To say that an acid is monoprotic is state that it is capable of donating one proton when it dissociates.

Mahli Martinez 2I

In sum, Hess's Law states that the change in energy in an overall chemical reaction is equal to the sum of the energy changes in the reactions that compromise the overall reaction. With this law, we are able to add the enthalpies of said reactions to calculate the total enthalpy of the system (and d...

Mahli Martinez 2I

He has not said anything specific yet, but I am sure that a detailed email will be sent out beforehand letting us know what we'll be tested on. My guess is that we will be tested on content from week 1 up until the end of this week.

Mahli Martinez 2I

For a reaction, to be endothermic, that means that it requires heat to actually take place. For something to melt, heat must be applied to break the bonds and convert a solid to a liquid.

Mahli Martinez 2I

I was wondering this too! It is possible that we could have the option of doing either/or, but I am honestly unsure. For now, I'll just assume that he'll do class in person but I may be wrong.

Mahli Martinez 2I

Usually, the problem will distinguish which to use and we likely wont have a problem that asks us to convert the two, since they are so close in value (1 atm = approx 1.013 bar).

Mahli Martinez 2I

There are three!! There's freezing, which is the transition from liquid to solid, Condensation, which is the transition from gas to liquid, and deposition, which is gas to solid.

Mahli Martinez 2I

Ka is the acid dissociation constant and is used to represent the strength of the acid. pKa is the negative log of Ka. The large the Ka value, the smaller the pKa and the stronger the acid.

Mahli Martinez 2I

Ka is the acid dissociation constant and is used to represent the strength of the acid. pKa is the negative log of Ka. The large the Ka value, the smaller the pKa and the stronger the acid.

Mahli Martinez 2I

Condensation is an exothermic process! Think about the phase change. Going from gas to liquid releases energy.

Mahli Martinez 2I

A smaller pH value means a higher presence of hydrogen ions, thus a more acidic solution.

Mahli Martinez 2I

Ka is specific to weak acids, while K is the general equilibrium constant.

Mahli Martinez 2I

Q represents the reaction quotient and represents the ratio of products to reactants at any time. K represents the equilibrium constant for when the reaction is in equilibrium.

Mahli Martinez 2I

The only factor that really changes K would be temperature, as K remains constant so long as temperature is constant.

Mahli Martinez 2I

It depends. If the reaction is favoring products (reaction shifted to the right), the reactant change would be negative. If the reactants are being favored, then more reactants would be made, making the change positive in an ICE table.

Mahli Martinez 2I

The two values have an inverse relationship. When volume increases, pressure decreases, and vice versa.

Mahli Martinez 2I

Hi! I am certain that we keep the same account, since it is already linked to our UID. All I would advise is to update your name so that it has your discussion section number, which will make it easier for your TA to find your posts.

Mahli Martinez 2I

Achieve is designed so each question has unlimited attempts. Also your grade may not be fully updated, so the grade that shows on CCLE does not always reflect an up-to-date record.

Mahli Martinez 2I

By definition, Q is the reaction quotient while K is the equilibrium constant. Q is used to represent the ratio of products/reactants at any given time during the reaction. We can use Q and K and compare both values to determine in which way the reaction will proceed.

Mahli Martinez 2I

I do believe that in this case, we would assume a temperature of 25 degrees celsius, or 298 K, depending on which SI units are asked for.

Mahli Martinez 2I

No, the addition of a catalyst would not affect K. It would likely cause a shift in the reaction and a speeding up of it.

Mahli Martinez 2I

Because it has a positive charge, it is looking to accept electrons to neutralize the charge, thus making it an acid (electron acceptor).

Mahli Martinez 2I

Remember that the values of pH and pOH added together equal to 14! Using that and the formulas Lavelle provided, these calculations are fairly simple. Say for example, a problem states that the pH of a solution is equal to 2.9 and it wants the pOH, all you have to do is subtract the pH value from 14...

Mahli Martinez 2I

To convert pH to [H+], use the formula pH= 10^-pH. Some scientific calculators actually show this as the inverse calculation!

Mahli Martinez 2I

From what I have heard, we should know them by the end of finals week :)

Mahli Martinez 2I

Yes! I do believe you can make them up at any point in the quarter, it's just better to do them ASAP to keep track of them.

Mahli Martinez 2I

H2O has a bent shape, which can be attributed to the lone pairs on oxygen that repel each other.

Mahli Martinez 2I

Generally, electronegativity increases as you move along the periodic table, and decreases as you move down, meaning that the elements in the upper right hand of the periodic table have pretty high electronegativity (close to fluorine, which is the most electronegative).Think of it as the closer it ...

Mahli Martinez 2I

The number you should be implementing in the equation should be [H+], or the concentration of H+. It usually provides this number if it wants you to calculate the pH, or in some cases, the pOH.

Mahli Martinez 2I

From what I have heard from other people who have taken the 14 series in the past, Chem14B does build off of concepts we learned about this quarter, but introduces many new topics.

Mahli Martinez 2I

I do believe that the other grade cutoffs are normal as they are (ex. 80-89% being a B). The C- being down to 200 points out of 400 is the only exception. Other than that, calculate your grade as you normally would.

Mahli Martinez 2I

Ligands are classified as a type of Lewis Base. However, not all Lewis Bases are ligands.

Mahli Martinez 2I

I personally am going to go over the outlines and practice problems provided to us, placing emphasis on what I feel I am lacking on.

Mahli Martinez 2I

Hi! The professor has yet to announce exactly how many questions but I am sure that an email announcing details of the final will come out soon.

Mahli Martinez 2I

The strength of an acid is reflected by how completely it dissociates in water. The bond between HF is stronger due to Fluorine's higher electronegativity, so it won't dissociate as much as HCl. Thus, HCl is a stronger acid.

Mahli Martinez 2I

Pi bonds are formed by the overlapping of p orbitals on adjacent atoms, while sigma bonds are formed by orbitals overlapping end-to-end. One important thing to note is that sigma bonds are stronger.

Mahli Martinez 2I

If I'm not mistaken, this arrow signifies a reversible reaction. The forward reaction is the reaction that yields the products to the right, while the reversed reaction moves to the left. The reaction can proceed in both directions.

Mahli Martinez 2I

My TA told me to look at the regions of electron density around the central atom. You will have to determine which is the central atom and counting the bonds/ lone pairs surrounding it. Be careful though, as a double bond still counts as a single region of electron density. Take CH4 for example. The...

Mahli Martinez 2I

No, s orbitals only have the ability to form sigma bonds!

Mahli Martinez 2I

You have to go to your TA's office hours if you want to discuss your results! Other than that, we can't access our results.

Mahli Martinez 2I

Midterm results are up!! Also, I am thankful for my family and friends :)

Mahli Martinez 2I

Hey! In my opinion, I wouldn't take all stem classes in a single quarter. While it may be tempting to get things over with and load up your schedule, make sure you are going to have time for your assignments and your self, first and foremost. If you do decide to take all of this though, I wish you l...

Mahli Martinez 2I

Yes! The final is indeed cumulative!

Mahli Martinez 2I

I do not see context in which Lavelle will require of us to memorize boiling points of any specific molecules for calculations. Like in this past midterm, he really wants us not to be able to determine exact boiling points with little to no information, rather to be able to predict differences of bo...

Mahli Martinez 2I

Prefixes are so important in the physical science world. So 'intra' means within and ' inter ' means between. In terms of chemistry, intra would refer to bonds within the molecule, while intra would mean bonds between molecules. I remembered this by thinking of other words that being with inter, suc...

Mahli Martinez 2I

Thank you so much!!

Mahli Martinez 2I

Yep! Think about the bigger radius and what that would mean. The increase in radius means further distance which means longer bonds. As we know, longer bonds are easier to break.

Mahli Martinez 2I

Based off the hw we had, I definitely think knowing Lewis Structures will be so important. Knowing intermolecular forces also seems like a big thing, knowing how to distinguish them and such. Bond lengths, bond strength, formal charges, resonance structures, all that stuff.

Mahli Martinez 2I

Hello! As to determining which structure is more favorable by looking at formal charge, you should look to which structure has the closest charge to 0. In this case, more than one has charge equal to 0. So, look to whichever structure has the negative charge on the more electronegative atom. In this...

Mahli Martinez 2I

Okay I may ramble a bit so I'm sorry in advance! Lo-fi is very soothing imo. I love The Marias and their music, so listening to their songs help me destress a lot. Chinese meditation music also helps so much, as do artists such as Ichiko Aoba and Lamp. Bossa nova type music is very calming.

Mahli Martinez 2I

I think almost any calculator is acceptable, with the exception of one on our devices of course. Throughout all of the science courses I have taken, a scientific calculator has definitely been the most helpful.

Mahli Martinez 2I

As of right now, I don't think so. I do know there is a cumulative amount they check for at the end of the quarter so perhaps just keeping track of them will help!

Mahli Martinez 2I

I am not 100%, but from what I have heard it will be the materials not covered on the first midterm in week 4 up until week 7 materials. Will update you!

Mahli Martinez 2I

Thank you so much for this! Reading this really gave me hope.

Mahli Martinez 2I

Hi! I swear by listening to classical and lo-fi music. Lots of research has discussed the benefits of listening to classical music by studying. Sometimes I do like listening to my favorite songs on rotation but not when I want to be super focused on my work, since I can find myself singing along to ...

Mahli Martinez 2I

Yes! It is due tonight at 11:59 p.m.!

Mahli Martinez 2I

There's a lot of things you can do! For starters, trying to read the entirety of your notes 5 minutes before does not help. At that point, you know what you know and it'll be okay. Set up a study routine that works for you! Not everyone can study for 8 hours in a single sitting and that's okay! Also...

Mahli Martinez 2I

Music, Music, Music. I love listening to dreampop, lo-fi, classical, meditation music. But listen to whatever winds you down. I find music to be a good distraction from the real world, a temporary escape if you will.

Mahli Martinez 2I

An email was just sent out saying we will receive our results in a few days!!

Mahli Martinez 2I

Hi! I do find myself reading the textbook once I need more help understanding a certain concept or idea. If you find yourself intimidated, maybe refer to some of the modules Lavelle has provided? Those are always pretty helpful.

Mahli Martinez 2I

I really relied heavily on Khan Academy when I took AP Chemistry a while back and I have found it to be helpful so far as well. I also really like LearnCheme and the chem modules on Lavelle's class site as well.

Mahli Martinez 2I

Hi! The units for 1 joule are as follows
kg*(m^2)/(s^2)

Mahli Martinez 2I

Hi! I have taken chemistry before, but I will be honest in saying that it has been a while and I have needed major memory refreshment. I took honors chem my freshman year of high school and AP chemistry the following year, so it has been years since I was in a chemistry course, let alone one this ri...

Mahli Martinez 2I

I do believe that it would be useful to memorize it, but if I have heard correctly, there will be constants and such provided to us on any exam. I would not stress about worrying it, unless it is specified that we will have to know constants by memory.

Mahli Martinez 2I

I am going to approach it as I usually do, by doing practice problems that have been suggested by the professor. I will probably watch some videos but wont be rewatching lectures or anything like that since it would not help much.

Mahli Martinez 2I

If I am not mistaken, those problems are simply for practice! It would be specified if we had to turn them in on any form.

Mahli Martinez 2I

This example would be both accurate and precise. Because of the shots being very clustered together, the arrows would be precise. The fact that they are all in the center means the shots were accurate.

Mahli Martinez 2I

Yes! I can not recall an instant in a chemistry course where I was asked to list the theoretical yield in units that weren't grams.

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