CHEMISTRY COMMUNITY

JooHyun Koh 1H

Q: What do you call a clown who's in jail?
A: A silicon.

JooHyun Koh 1H

Wouldn't bond lengths be different within the ozone molecule because there is a single bond and a double bond and a double bond is shorter than a single bond?

JooHyun Koh 1H

^ Whether an acid/base is strong or weak will tell us how it behaves in water. Strong acids and bases will ionize/dissociate completely in water, while weak acids and bases will not. This information is crucial in figuring out the molarity of a solution and how the addition of acids and bases affect...

JooHyun Koh 1H

Q: Why do chemistry students do well when working with NaOH?
A: Because it's pretty basic stuff.

JooHyun Koh 1H

The charge of the ligand is listed on Table 17.4 of the textbook

JooHyun Koh 1H

I converted the molarity of Na2O into moles, which I got 115.5 moles, and then I doubled to get moles of OH, since Na2O + H2O <--> 2Na+ + 2OH--. So, I got 1.1M for [OH--], which means the pOH is -.04, making the pH 14.04. IS this right? can pH be over 14 and can pOH be negative?

JooHyun Koh 1H

To figure out hybridization, say SO2 for example, do u only need to look at the number of sigma bonds and lone pairs? So would the hybridization on sulfur in SO2 be sp2 because it has 2 sigma bonds and one pair of lone pair electrons?

JooHyun Koh 1H

The composition of bonds refer to sigma bonds and pi bonds. A single bond is comprised of one sigma bond, while a double bond is made of a sigma bond and a pi bond. For example, a H and C bond in CH2CHCHO is made up of a sigma bond between H1s and C2sp^2 because it is a single bond. For another exam...

JooHyun Koh 1H

Amphoteric means that it can either function as a base or an acid in a chemical reaction, meaning it can either accept or donate an H+ ion (under the Bronsted definition). One example of an amphoteric compound is water. For example: H2O + HCl <--> Cl-- + H3O+ Since H2O accepted a proton, it acts as ...

JooHyun Koh 1H

Does a sigma bond always have to be in the 2pz orbital?

JooHyun Koh 1H

This is mentioned in Chapter 3.3 in the textbook, but I am having a hard time understanding the concept of why NaCl has a lower energy than the separated sodium and chlorine atoms. I'm just confused on where they got the number for the energy released during the formation of NaCl (which is 787 kJ/mo...

JooHyun Koh 1H

Yea, My TA said that Professor Lavelle didn't really cover electron affinity and said it would most likely not be on the exam.

JooHyun Koh 1H

To answer the questions listed above... 1)What will happen if I increased intensity? Intensity (the number of photons) has no effect on the velocity of the electron because the photoelectric effect illustrates a 1-to-1 interaction between photons and electrons of the metal. This is shown in the exam...

JooHyun Koh 1H

I remember there being a specific order in which we have to draw the dots (that represents valence electrons) around the element, but I have forgotten. Can someone explain to me the order?

JooHyun Koh 1H

Exactly, as stated above, the correct units should be used. But nobody said the correct units, but only alluded to it. So, yea, in solving a De Broglie's equation, using kg for the mass is important for 1 J = 1kg*(m^2)*(s^-2)

JooHyun Koh 1H

Energy can never be negative; however, delta E, can be. Delta E is what we get when we try to figure out what the change in energy is when an electron jumps energy levels. Energy of the photon emitted during that process is positive, because according to the conversation of energy, no energy can be ...

JooHyun Koh 1H

As stated above, 1 eV = 1.60218 * 10^-19 J; however, sometimes eV will have the same prefixes that the metric system uses, so it's important to take that into account. For example 1 keV = 1000 eV, and then u can convert that to joules if necessary.

JooHyun Koh 1H

The equation E = hv explains why shorter wavelengths have more energy than longer wavelengths. Shorter wavelengths equate to higher frequency due to the c = v*lambda equation, and frequency (v) is directly proportional to the energy of a photon

JooHyun Koh 1H

I don't think so because if the question will probably provide the wavelength of visible light, like in HW 1.16, but I'm not 100% sure if we don't need to memorize it. It might be nice to know like the red and violet wavelengths, 700 nm and 400 nm, respectively.

JooHyun Koh 1H

I know that sig figs aren't that important this test, but I think it'd be helpful to make it a habit of writing the answer in the right sig figs (my TA said that sig figs only matter for the answer and not in the actual process) since it might be useful later in the course or maybe in other courses

JooHyun Koh 1H

I think it's because this question isn't really asking to find the initial volume of the Cu(NO3)2 solution, it's asking for a conversion. So, to solve this problem, you would get the number of moles of Cu(NO3)2 by multiplying the Molarity by the volume, which is (.3842 M)*(.04388 L) = 0.01686 mol Cu...

JooHyun Koh 1H

I would agree with the person above about checking with your TA, for each might be different. But, my TA did say we were expected to memorize and know the chemical formulas of common compounds. So, I would probably advising at least like looking over that, better safe than sorry!

CHEMISTRY COMMUNITY

Search found 22 matches

Re: Post All Chemistry Jokes Here

Bond length in Ozone (French Toast #33b)

Re: Strength between 2 weak/strong acids/bases

Re: Post All Chemistry Jokes Here

Re: Oxidation Numbers and how to get them

Re: Calculating pH of a solution given molarity

How to figure out hybridization

Re: 4.95 [ENDORSED]

Re: Amphoteric Compiund

Sigma bonds

Energetics of Ionic Bond Formation

Re: Trends to Know

Re: Photoelectric Problems

Order of Dots

Re: HW 1.39 [ENDORSED]

Re: Negatives and Planck's Constant in finding the energy of a transitioning hydrogen atom?

Re: Converting eV to J

Re: Why do shorter wavelengths have more energy than longer wavelengths?

Re: Light Spectrum

Re: Basic Sig Figs

Re: Review Worksheet from Lab Week 1 Question 1 [ENDORSED]

Re: Common Compounds to know