CHEMISTRY COMMUNITY

Chloe Little 3K

I believe it tells you the percent of collisions that occur with the correct orientation.

Chloe Little 3K

If the collisions aren't in the correct orientation, then there won't be a reaction.

Chloe Little 3K

just relaxing and spending time with my family

Chloe Little 3K

You use the Nernst equation to calculate E.

Chloe Little 3K

The single lines indicate an interface between phases that are in contact with each other. For example, in my question, Pb and PbCl2 were on one side while Ag and AgCl2 were on the other side. Here, Pb and PbCl2 would be separated by a single and Ag and AgCl2 would be separated by a single line.

Chloe Little 3K

In galvanic cells, the (spontaneous) redox reaction is powering the electric current whereas in electrolytic cells, the electric current is powering a non spontaneous redox reaction.

Chloe Little 3K

You need to have 50 points by the end of the quarter and having more than 50 doesn't give you extra credit.

Chloe Little 3K

The workload is very manageable and Dr. Casey is an amazing professor! But regardless of the professor, the class is fairly easy. Almost all of the concepts are things that we've covered in chem 14a or 14b, and the few concepts that we haven't covered are very easy to understand.

Chloe Little 3K

On the class planner, it says that they will be online but not recorded, but I don't know if this is necessarily the case.

Chloe Little 3K

I think that this is because work is done in order to achieve equilibrium or at least move closer to equilibrium. And so if the reaction is already at equilibrium, it doesn't do any work.

Chloe Little 3K

I'm taking Chem 14C, Physics 5C, and a GE. I was going to take Chem 14CL too but it's filling up pretty fast.

Chloe Little 3K

Lavelle hasn't ever mentioned curving test grades, so I don't think that it's very likely.

Chloe Little 3K

This is because one degree unit on the Celsius scale is equivalent to one degree unit on the Kelvin scale. So, as long as all your temperatures are in Celsius or all your temperatures are in Kelvin, it doesn't matter which you use.

Chloe Little 3K

When work is done by a system, the system is using energy, meaning that energy is being released from the system to the surroundings, which is why work is negative. When work is done to a system, the system is gaining energy from the surroundings, so work is positive.

Chloe Little 3K

How should we determine the delta T when applying the q=mcdeltaT equation in this problem, since final temperature is not given because it is what we need to solve for? delta T would be T(final) minus T(initial), and since you know T(initial), when you use q = -q, you can solve for T(final). So, yo...

Chloe Little 3K

Isn't delta H negative when the reaction is exothermic, meaning heat is released from the solution?

Chloe Little 3K

For part A, you find q by multiplying the number of moles you have by the heat of combustion. Then you find the heat capacity of the calorimeter (C) by dividing q by the change in temperature. For part B, you use the equation q = C(delta T). And since it asks for the heat combustion, you divide q by...

Chloe Little 3K

It's not too difficult. I'm not sure how hard the exams are since we haven't had our midterm yet, but the homework is very manageable. You usually have one group lab activity and an individual lab report every week.

Chloe Little 3K

I'm not sure what most people do, but I'm taking 14BL right now and I'm planning on taking 14CL next quarter with chem 14C. Has it been hard to manage 14BL with 14B? Nervous about taking 14C and BL together next quarter but feel like I don't have much a choice. No it actually hasn't been too hard, ...

Chloe Little 3K

You use the equation q = mcΔT. The heat gained by the cold water is equal to the heat lost by the hot water, so q for the cold water is equal to negative q for the hot water.

Chloe Little 3K

I'm not sure what most people do, but I'm taking 14BL right now and I'm planning on taking 14CL next quarter with chem 14C.

Chloe Little 3K

This means that the heat of the surroundings has to equal the heat of the system. For example, if 200 J of heat was released from the system (meaning it left the system), this means that 200 J of heat was added to the surroundings.

Chloe Little 3K

I watched netflix and then caught up on homework for my other classes :)

Chloe Little 3K

Your rounded answer should have 4 sig figs which would be 4.044*10^-5 mol because when you divide, the number of significant figures in the answer should match the number of significant figures of the least precisely known number used in the calculation, meaning the number with the fewest sig figs. ...

Chloe Little 3K

Since he didn't mention a non-perfect system, I would assume the system is always a perfect system, unless stated otherwise.

Chloe Little 3K

Yes, I think generally all neutralization reactions are exothermic because every neutralization reaction involves the formation of water which releases heat, making it exothermic.

Chloe Little 3K

Yes, that's what it means.

Chloe Little 3K

The units of Kelvin and Celsius are essentially the same in that a temperature in Kelvin is just the temperature in Celsius + 273.15. So, for example, an increase of one Kelvin is the same as an increase of one degree Celsius.

Chloe Little 3K

If you're working with gases then for the constant pressure calorimeter, you use the molar heat capacity of a gas at constant pressure (Cp) and for the constant volume calorimeter, you use the molar heat capacity of a gas at constant volume (Cv).

Chloe Little 3K

I think that's something we need to look up or we'll be given it.

Chloe Little 3K

I think this would be considered exothermic because the reaction itself is releasing heat which then causes the temperature of the surroundings to increase. Because the reaction is releasing heat, it is considered exothermic.

Chloe Little 3K

Kelvin is always interchangeable with Celsius because raising the temperature of a substance by one degree Celsius is the same as raising the temperature by one Kelvin.

Chloe Little 3K

I listen to mostly alt rock and indie :) Some of my favorites are Arctic Monkeys, Cage the Elephant, Wallows, Clairo, and Surf Curse.

Chloe Little 3K

You more or less just have to memorize all the strong acids and bases and anything that isn't a strong base or acid is considered weak.

Chloe Little 3K

procrastinate less and meditate and do yoga more often

Chloe Little 3K

Hi, so from lecture, Dr. Lavelle talks about how we use the quadratic formula to solve for the x change value in ICE tables, and then proceeds to show how we omit the negative x value and use the positive one. What happens when we get two positive x values? Would we test both x values into the ICE ...

Chloe Little 3K

I love watching all the Harry Potter movies :) and also Coraline is one of my favorites too.

Chloe Little 3K

He does this to find the concentration. In the example there's 1.5 moles of PCL5 in a 0.5 L reaction vessel. So to find the concentration, you divide the moles by the volume which would be 1.5/0.5.

Chloe Little 3K

Kw is the autoprotolysis constant of water at 25 degrees Celsius, so it's only used for the reaction where water is forming hydroxide (OH-) and/or hydronium (H3O+) ions. You'd typically use it to find the concentration of H30+ or OH-.

Chloe Little 3K

I don't think there's really a strict deadline, as long as you have 50 posts by the end of the quarter.

Chloe Little 3K

I've found that doing the textbook problems has helped me a lot. I'd also suggest spreading out your studying and not just cram right before the midterms and final. Going to step up sessions and peer learning sessions can also be very helpful if there's something in particular that you're struggling...

Chloe Little 3K

It depends on the units that you're given, but I think we'll typically be using either one of those values.

Chloe Little 3K

I don't think there'll be any other audio-visual topics. The main forms of practice would be the Sapling homework problems and the textbook problems.

Chloe Little 3K

I think typically the answer is yes because when we're using ICE tables, the goal is usually to find the concentrations in order to calculate Kc and so you'd want to use molarity for the table.

Chloe Little 3K

I've heard that trying it through a different browser might help.

Chloe Little 3K

Hi, I was wondering if anyone knew if the Sapling questions were due this coming Sunday as in three days from now, or if it is due next Sunday as in a week and three days from now. I know Sapling says that the first assignment is due Sunday of week 2, but I did not want miss anything, so if someone...

Chloe Little 3K

Just a small correction to what was said above, an ideal gas won't turn into a liquid when the temperature is lowered (not raised).

Chloe Little 3K

This is the groupme for Chem 14b with Lavelle: https://groupme.com/join_group/62288203/dSSkobMS

Chloe Little 3K

A solvent is typically a liquid (l), such as water, and it is not included when calculating the equilibrium constant.

Chloe Little 3K

https://groupme.com/join_group/62288203/dSSkobMS

Chloe Little 3K

https://groupme.com/join_group/62288203/dSSkobMS

Chloe Little 3K

Metalloid oxides are generally amphoteric but this doesn't mean that all amphoteric compounds are metalloid oxides. Bi2O3 is an amphoteric compound because it has both basic and acidic characters.

Chloe Little 3K

P-orbitals have one nodal plane, and d-orbitals have two nodal planes.

Chloe Little 3K

Denticity refers to the number of donor groups in a single ligand that bind to a central atom in a coordination complex. For example, if a ligand binds at one site, meaning it donates 1 electron pair, it is said to be monodentate. Denticity basically just refers to how many site a ligand binds to, o...

Chloe Little 3K

I think that it's just another way of defining acids and bases. A Bronsted acid means that it is a proton donor and a Bronsted base means that it is a proton acceptor. Similar to how a Lewis acid means that that species accepts an electron pair and a Lewis base means that that species donates an ele...

Chloe Little 3K

Cobalt is in the vitamin.

Chloe Little 3K

I'm a biology major and honestly the main reason I chose it is because the requirements for my major line up with the requirements for medical school and I don't really have a strong passion for any other subject. But I think you should major in whatever interests you or whatever you're passionate a...

Chloe Little 3K

I think in that case it would just be called iron.

Chloe Little 3K

Yes, the equatorial bond angles are 120° and the axial bond angles are 90° and 180°.

Chloe Little 3K

oh got it! So do I have to have all 5 posts every week or I disperse the number of posts whenever, but make sure I have 40 by the end of this week? You need to have 50 posts in total by the end of the quarter (by the end of week 10). And you can post whenever, it doesn't have to be strictly 5 per w...

Chloe Little 3K

All single bonds are sigma bonds. A double bond has one sigma bond and one pi bond. And a triple bond has one sigma bond and two pi bonds.

Chloe Little 3K

I go on walks with my dogs and my family and sometimes I do yoga.

Chloe Little 3K

Yes, you can take Chem 14BL after you take Chem 14b, they don't have to be taken at the same time.

Chloe Little 3K

For the dipoles to cancel out, they must point in opposite directions. In cis-dichloroethene, the dipoles are pointing in different directions but they are not completely opposite. In other words, the directions of the dipoles must be 180 degrees apart for them to cancel out.

Chloe Little 3K

Yes that's what they're referring to.

Chloe Little 3K

Having ten electrons in the d sub shell is more favorable than filling the s sub shell, so in this case, the electrons would fill up the d sub shell before the s.

Chloe Little 3K

London dispersion forces occur between all atoms and molecules whereas dipole-dipole interactions can only occur between molecules that have dipoles.

Chloe Little 3K

I think if you go to your TA's office hours (or any TA's office hours) you can review Midterm 1 with them.

Chloe Little 3K

Ag has 11 more electrons than Kr, so you would start with the electron configuration for Kr which is represented by [Kr] and then fill the following shells with the remaining 11 electrons. [Kr] = 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶ so the orbitals that come after this are 4d and 5s. Typically, you'd fill the ...

Chloe Little 3K

Discussion sections don't affect your grade, they're really just for extra practice.

Chloe Little 3K

The points through week 4 are posted on CCLE under Grades. If you've been posting 5 times a week, then you should have a total of 20 points. By the end of the quarter you need 50 points, which means you need a total of 50 posts.

Chloe Little 3K

For me, doing the textbook questions was very helpful, as well as reviewing my notes on the lectures.

Chloe Little 3K

l can be any integer between 0 and n-1. So if n=6, then l can be anywhere between 0 and 5.

Chloe Little 3K

Lewis structures show the number of valence electrons each atom has, and each atom can typically only have eight valence electrons at most (with some exceptions), hence the maximum of 4 lone pairs. This goes for all elements, transition metals included.

Chloe Little 3K

I think that was a mistake. Oxygen does have a lower ionization energy than nitrogen.

Chloe Little 3K

The number of electrons an element has is equal to its atomic number.

Chloe Little 3K

I think you can put them on any side, I don't think it matters.

Chloe Little 3K

It's just the charge of the molecule. So when writing the Lewis structure for the molecule NO3-, you would put brackets around the structure and a minus in the top right corner. It just depends on the charge of the molecule. For example, if the molecule's charge was +1, you'd put a + in the corner o...

Chloe Little 3K

It means the 4s orbital is filled before the 3d orbital. When you write out the electron configuration, though, the 3d is still written before the 4s (ex. scandium would be written as [Ar]3d^1 4s^2) even though the 4s gets filled first.

Chloe Little 3K

Z means the atomic number of an element. So for example, the atomic number of hydrogen is 1, so you would add 1 electron to the electron configuration.

Chloe Little 3K

Javier Perez M 2J wrote:Will we be provided with conversion units for the exam? (such as how many nanometers are in a meter and ml in a liter)
Or are we expected to memorize this?

Some conversions are on the constants and equations sheet, like kg to g, angstroms to meters, nanometers to meters, and picometers to meters.

Chloe Little 3K

I've been taking notes on all the lectures and doing all of the practice textbook questions assigned in the syllabus.

Chloe Little 3K

I'm not entirely sure, but I think light behaves like a particle, since the atomic spectra experiment has to do with photons of energy which would behave as particles, not waves.

Chloe Little 3K

Since there's no way to know how much H2O you began with, I think it's safe to assume that PCl3 is the limiting reagent.

Chloe Little 3K

He was talking about how the 4s orbital is occupied before the 3d orbital, but this doesn't change the way we write the electron configuration. You'd still write 3d before 4s, for example scandium would be: [Ar] 3d^1 4s^2. But for potassium and calcium, the 3d orbital isn't occupied, so it'd be writ...

Chloe Little 3K

1 Electron volt (eV) = 1.602176565 x 10-19 joules (J)

Chloe Little 3K

1 volt (eV) = 1.602176565 x 10^-19 joules (J)

Chloe Little 3K

Since it's multiple choice, there isn't going to be any partial credit. But, according to my TA, there won't be a lot of questions that depend on your answers to previous questions.

Chloe Little 3K

3.24x10^-20 J is the energy for a single photon. To find the number of photons, you need to divide the heat absorbed by the energy per photon. So you would divide 26.19 J by 3.24x10^-20 J/photon.

Chloe Little 3K

What I did was convert the 5.15 ounces to kilograms and the 92 mph to meters/second. Then I used the De Broglie equation: wavelength = h/(mass*velocity).

Chloe Little 3K

I got 1.10 * 10^-34

Chloe Little 3K

how would we go about calculating the wavelength range?

Chloe Little 3K

n is the energy level that the electron is at. the lower the n value, the closer the electron is to the nucleus of the atom and the lower its energy is. When the electron is at n=1, it must absorb energy to move to a higher energy level such as n=2 or n=3. And when the electron is at an energy level...

Chloe Little 3K

I don't think that high frequency necessarily causes a shorter wavelength. But if the frequency is high then this means that the wavelength will be short, and if the frequency is low, that means the wavelength will be long. And different metals do require different energies to eject electrons, so ye...

Chloe Little 3K

And because you need to have a certain wavelength/frequency to eject electrons, increasing the light intensity alone would not cause electrons to be ejected if none were ejected in the first place because increasing the light intensity only increases the number of photons, not the wavelength or freq...

Chloe Little 3K

I think that increasing the light intensity just means that you're increasing the number of photons.

Chloe Little 3K

Atomic spectra are the transitions of electrons between electronic energy levels in isolated atoms. They are affected by interactions of the transitioning electrons with the nuclei spins and with the other electrons in the atom. Molecular spectra involve transitions in molecules with two or more ato...

Chloe Little 3K

Also, the first thing you would need to do for this problem is balance the reaction. For more help, I'd suggest watching today's lecture on how to solve a stoichiometry problem.

Chloe Little 3K

The percent yield is the actual yield divided by the theoretical yield multiplied by 100%. So, if the percent yield is 100%, then that means the actual yield divided by the theoretical yield is equal to one. This means the actual yield is equal to the theoretical yield. So, you'd find the theoretica...

Chloe Little 3K

When you multiply or divide several numbers, or when you take roots, the number of significant figures in the answer should match the number of significant figures of the least precisely known number used in the calculation. For example, in 3.73×5.7=21, 3.73 has three significant figures and 5.7 has...

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