Search found 22 matches

by JooHyun Koh 1H
Wed Jun 13, 2018 9:38 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 786291

Re: Post All Chemistry Jokes Here

Q: What do you call a clown who's in jail?
A: A silicon.
by JooHyun Koh 1H
Wed Jun 13, 2018 8:06 pm
Forum: Bond Lengths & Energies
Topic: Bond length in Ozone (French Toast #33b)
Replies: 1
Views: 193

Bond length in Ozone (French Toast #33b)

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?
by JooHyun Koh 1H
Wed Jun 13, 2018 7:23 pm
Forum: Lewis Acids & Bases
Topic: Strength between 2 weak/strong acids/bases
Replies: 5
Views: 204

Re: Strength between 2 weak/strong acids/bases

^ 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...
by JooHyun Koh 1H
Wed Jun 13, 2018 3:27 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 786291

Re: Post All Chemistry Jokes Here

Q: Why do chemistry students do well when working with NaOH?
A: Because it's pretty basic stuff.
by JooHyun Koh 1H
Wed Jun 13, 2018 3:23 am
Forum: Naming
Topic: Oxidation Numbers and how to get them
Replies: 4
Views: 281

Re: Oxidation Numbers and how to get them

The charge of the ligand is listed on Table 17.4 of the textbook
by JooHyun Koh 1H
Tue Jun 12, 2018 12:28 am
Forum: Calculating the pH of Salt Solutions
Topic: Calculating pH of a solution given molarity
Replies: 3
Views: 203

Re: Calculating pH of a solution given molarity

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?
by JooHyun Koh 1H
Mon Jun 11, 2018 7:57 pm
Forum: Hybridization
Topic: How to figure out hybridization
Replies: 5
Views: 594

How to figure out hybridization

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?
by JooHyun Koh 1H
Mon Jun 11, 2018 11:29 am
Forum: Hybridization
Topic: 4.95 [ENDORSED]
Replies: 1
Views: 133

Re: 4.95 [ENDORSED]

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...
by JooHyun Koh 1H
Thu Jun 07, 2018 1:34 pm
Forum: Amphoteric Compounds
Topic: Amphoteric Compiund
Replies: 2
Views: 168

Re: Amphoteric Compiund

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 ...
by JooHyun Koh 1H
Thu Jun 07, 2018 1:19 pm
Forum: Sigma & Pi Bonds
Topic: Sigma bonds
Replies: 1
Views: 140

Sigma bonds

Does a sigma bond always have to be in the 2pz orbital?
by JooHyun Koh 1H
Sun Jun 03, 2018 1:09 pm
Forum: Ionic & Covalent Bonds
Topic: Energetics of Ionic Bond Formation
Replies: 2
Views: 128

Energetics of Ionic Bond Formation

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...
by JooHyun Koh 1H
Mon May 07, 2018 11:42 pm
Forum: Trends in The Periodic Table
Topic: Trends to Know
Replies: 12
Views: 390

Re: Trends to Know

Yea, My TA said that Professor Lavelle didn't really cover electron affinity and said it would most likely not be on the exam.
by JooHyun Koh 1H
Mon May 07, 2018 11:39 pm
Forum: Photoelectric Effect
Topic: Photoelectric Problems
Replies: 4
Views: 214

Re: Photoelectric Problems

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...
by JooHyun Koh 1H
Mon May 07, 2018 11:32 pm
Forum: Lewis Structures
Topic: Order of Dots
Replies: 11
Views: 290

Order of Dots

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?
by JooHyun Koh 1H
Fri Apr 20, 2018 2:28 pm
Forum: DeBroglie Equation
Topic: HW 1.39 [ENDORSED]
Replies: 8
Views: 277

Re: HW 1.39 [ENDORSED]

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)
by JooHyun Koh 1H
Wed Apr 18, 2018 2:07 pm
Forum: Properties of Light
Topic: Negatives and Planck's Constant in finding the energy of a transitioning hydrogen atom?
Replies: 2
Views: 119

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

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 ...
by JooHyun Koh 1H
Wed Apr 18, 2018 2:04 pm
Forum: Photoelectric Effect
Topic: Converting eV to J
Replies: 4
Views: 152

Re: Converting eV to J

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.
by JooHyun Koh 1H
Fri Apr 13, 2018 2:09 pm
Forum: Photoelectric Effect
Topic: Why do shorter wavelengths have more energy than longer wavelengths?
Replies: 4
Views: 133

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

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
by JooHyun Koh 1H
Wed Apr 11, 2018 2:26 pm
Forum: Properties of Light
Topic: Light Spectrum
Replies: 2
Views: 144

Re: Light Spectrum

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.
by JooHyun Koh 1H
Mon Apr 09, 2018 2:12 pm
Forum: Significant Figures
Topic: Basic Sig Figs
Replies: 13
Views: 841

Re: Basic Sig Figs

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
by JooHyun Koh 1H
Sat Apr 07, 2018 8:18 pm
Forum: Molarity, Solutions, Dilutions
Topic: Review Worksheet from Lab Week 1 Question 1 [ENDORSED]
Replies: 1
Views: 571

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

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...
by JooHyun Koh 1H
Fri Apr 06, 2018 5:15 pm
Forum: Balancing Chemical Reactions
Topic: Common Compounds to know
Replies: 3
Views: 153

Re: Common Compounds to know

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!

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