Search found 25 matches

by Jamie_Lin_3I
Tue Mar 14, 2017 12:24 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation
Replies: 2
Views: 421

Re: Arrhenius Equation

Hi! I believe your equation actually works. I tried using the one you wrote and the one in the equation sheet and I got the same answer. I think one of the problem is that you used the wrong T2 (temperature). It should be 350K not 348K because the second temperature is 77 degree Celsius not 75 degre...
by Jamie_Lin_3I
Sun Mar 12, 2017 12:24 am
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Eclipsed and staggered
Replies: 1
Views: 262

Re: Eclipsed and staggered

Hi! Molecules are constantly converting between the different conformations that they have. When collisions occur, a molecule in a stable position such as a staggered ethane could change conformation to a less stable position. However, most of the time, molecules at a certain temperature would spend...
by Jamie_Lin_3I
Fri Mar 03, 2017 12:40 pm
Forum: *Alkynes
Topic: Naming an Alkyne
Replies: 1
Views: 522

Re: Naming an Alkyne

Hello! I would suggest drawing the structure out with a chain of 4 carbons and a chain of 5 carbons. You will notice that for the chain of 5 carbons, the structure doesn't quite work out. There are 2 CH3. If you use the 5 carbon chain, you can only place the 2 groups of CH3 at the ends of the struct...
by Jamie_Lin_3I
Fri Feb 24, 2017 9:47 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-equilibrium approach
Replies: 1
Views: 258

Pre-equilibrium approach

Will the experimentally determined rate law always be given for a problem involving pre-equilibrium approach? if not, would the rate law simply be that of the slowest step with intermediates included, or is there a way to approach the problem to substitute the intermediate without knowing the experi...
by Jamie_Lin_3I
Sun Feb 19, 2017 3:12 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Ideal Gas Constant (R) vs Molar Heat Capacity
Replies: 2
Views: 884

Re: Ideal Gas Constant (R) vs Molar Heat Capacity

Hello! I would suggest reading chapter 8.7 the box if you want a more detailed explanation and 8.10 if you want the chart of molar heat capacity of ideal gases. (it might be a clearer explanation) The different values we use for molar heat capacity of idea gases has to do with the consideration that...
by Jamie_Lin_3I
Fri Feb 10, 2017 8:00 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Crystal Problem on Quiz 1
Replies: 1
Views: 323

Re: Crystal Problem on Quiz 1

Hello! I'm not sure if we had the same question or what you meant by perfect. But if you're referring to the question about which molecule, H2O or HOCl, has larger molar entropy at T=0 K, then HOCl would have a larger molar entropy. This is because the two atoms attached to O in H2O is the same, whi...
by Jamie_Lin_3I
Sun Feb 05, 2017 4:00 pm
Forum: Balancing Redox Reactions
Topic: Reduction Potentials
Replies: 2
Views: 225

Re: Reduction Potentials

Using standard reduction potentials and determining which one to make negative is kind of similar to using Hess's law when finding change in reaction enthalpy. You are essentially adding together the two half reactions to obtain the overall redox reaction. Let's say, if one of the product you see in...
by Jamie_Lin_3I
Tue Jan 24, 2017 10:27 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Reversible vs. Irreversible Processes?
Replies: 1
Views: 256

Re: Reversible vs. Irreversible Processes?

Hello! I had trouble with this topic as well, so it took me a while to grasp the idea. An irreversible process, like you said, is a case when the pressure of the system is equal to the external pressure or when the difference between the pressure of the system and the external pressure is so insigni...
by Jamie_Lin_3I
Thu Jan 19, 2017 7:16 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units involved in calculating the work done [ENDORSED]
Replies: 1
Views: 259

Re: Units involved in calculating the work done [ENDORSED]

Hello! If you want to read about pressure units, I would suggest reading Chapter 5 Section 3. It explains the unit of Torr, bar, pascals, and atmospheres and their relations to each other. For this problem, since there is a constant pressure, you should use the equation w = - external pressure x cha...
by Jamie_Lin_3I
Wed Jan 11, 2017 11:16 pm
Forum: Calculating Work of Expansion
Topic: Calculating the work done when water freezes and expands
Replies: 1
Views: 1931

Re: Calculating the work done when water freezes and expands

Hello Kira! For this question, the answer key in the textbook does say -0.86 kJ, but from previous posts on chemistry community most students were getting -0.98 or -0.94 (that is if you rounded the answers until the end). However, I'm not sure which exactly is the correct answer... To get an answer,...
by Jamie_Lin_3I
Wed Jan 11, 2017 11:02 pm
Forum: Calculating Work of Expansion
Topic: Self Test 8.1A on page 264
Replies: 1
Views: 195

Re: Self Test 8.1A on page 264

Hello Derek!
Yes, I got the same answer too -0.94 kJ. When I did the question I was confused as well. After googling it, it seems that people from previous years have the same question as well and have posted it here on chemistry community. I believe most students also commented that they got -0.94.
by Jamie_Lin_3I
Wed Nov 30, 2016 2:33 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 12.59
Replies: 1
Views: 225

Re: 12.59

Hi! If you think about NH3 in terms of of a Lewis Base definition (an electron pair donor) and the lewis structure of NH3, you'll realize that N has a lone pair that it can "donate" to form a coordinate covalent bond with a hydrogen proton coming from water. As for why... Since NH3 is a we...
by Jamie_Lin_3I
Sun Nov 27, 2016 4:51 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acidity and atomic radius
Replies: 1
Views: 523

Re: Acidity and atomic radius

Hello ~ When an atomic radius increases, the bond length also increase. When bond length increases, the bond is actually weaker than when the bond length is short. Think about HCl and HI. HI is a stronger acid because I has a greater radius. When the radius is bigger you can imagine the electron clo...
by Jamie_Lin_3I
Tue Nov 15, 2016 2:38 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Charge of an ion
Replies: 1
Views: 235

Re: Charge of an ion

Hi! I'm not sure about having to know it, but to figure out the oxidation number for the metal atom in coordination compounds/complexes it is better to just memorize the for the common polyatomic ions such as sulfate or carbonate. Type "polyatomic ions" into google and there should be a lo...
by Jamie_Lin_3I
Sun Nov 13, 2016 6:45 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Molecular Orbital Diagram
Replies: 1
Views: 253

Re: Molecular Orbital Diagram

We draw different diagrams for Z<8 and Z>8 because of s-p orbital mixing in elements of atomic number less than 8. For Z>8 elements the addition of protons pull 2s orbitals closer to the nucleus and provide better shielding for electrons in p orbitals. Hence, there is a greater energy difference bet...
by Jamie_Lin_3I
Tue Nov 01, 2016 10:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-Shaped?
Replies: 1
Views: 315

Re: T-Shaped?

I think if the lone pairs occupy the axial positions, they would be as far from one another as possible, but the lone pairs would now have to repel 3 bonded pairs at the equatorial position. If the lone pairs occupy two of the three equatorial positions, then it would exert repulsion to only 2 axial...
by Jamie_Lin_3I
Tue Nov 01, 2016 10:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dipole Moment
Replies: 3
Views: 363

Re: Dipole Moment

Typically when the two atoms involved in bonding are different atoms, they have different electronegativity. With different electronegativity, the atom with the higher electronegativity would pull on the electrons in the covalent bond more as it "wants" the electrons more. Thus, bonded ato...
by Jamie_Lin_3I
Tue Oct 25, 2016 1:28 pm
Forum: Octet Exceptions
Topic: lewis structure for(I_3)-
Replies: 1
Views: 337

Re: lewis structure for(I_3)-

Hi! For I3- Since iodine can expand its octet using the 5d subshell, Iodine can bond with more than 1 atom. Let's start with calculating the valence electrons... 7 valence of iondine X 3 atoms + 1 electron from charge = 22 electron Thus, the central iodine would be single bonded to the other two iod...
by Jamie_Lin_3I
Tue Oct 25, 2016 1:19 pm
Forum: Resonance Structures
Topic: (NH2)COCH3 Molecule structure
Replies: 1
Views: 394

Re: (NH2)COCH3 Molecule structure

Hi! I believe the O should be sticking out from the first C without hydrogen. This way you can double bond the O sticking out to the carbon or double bond nitrogen to Carbon for the two resonance If you put the O between the Carbon, for one resonance you would have to double bond the O to one carbon...
by Jamie_Lin_3I
Thu Oct 20, 2016 9:23 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Problem 2.81
Replies: 1
Views: 190

Re: Problem 2.81

Hello! You can find a detailed explanation for this question in section 2.10 of the textbook If you write out the electron configuration and draw out the orbitals for oxygen, nitrogen and fluorine, you can see that nitrogen has a half-filled 2p orbital and typically a half-filled orbital or a filled...
by Jamie_Lin_3I
Tue Oct 11, 2016 3:10 pm
Forum: Photoelectric Effect
Topic: Quiz 1 Prep [ENDORSED]
Replies: 1
Views: 452

Re: Quiz 1 Prep [ENDORSED]

Hello! When I read this question, I did have to read it again to reinterpret it in my own words. 1) Calculate the lowest frequency of light that will cause photoelectric emission. I believe this is just saying the minimum frequency of light that will cause the electron to emit from the metal (so it ...
by Jamie_Lin_3I
Tue Oct 11, 2016 3:00 pm
Forum: Molarity, Solutions, Dilutions
Topic: Quiz 1 Fall 2015 #5 [ENDORSED]
Replies: 2
Views: 502

Re: Quiz 1 Fall 2015 #5 [ENDORSED]

Hello! Regarding this question, I think EX M.4 in the Fundamental M section does a great job explaining this type of problem, specifically for combustion reactions. So to visually see the chemical equation... (since we don't know what the compound empirical formula is, let's substitute it as X) X + ...
by Jamie_Lin_3I
Fri Oct 07, 2016 5:40 pm
Forum: General Science Questions
Topic: QUIZ 1
Replies: 2
Views: 583

Re: QUIZ 1

I believe he said everything up to this Wednesday, meaning October 5th!
by Jamie_Lin_3I
Fri Oct 07, 2016 12:38 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Changing signs [ENDORSED]
Replies: 2
Views: 331

Re: Changing signs [ENDORSED]

Hello! Yes, when you use the Heisenberg uncertainty equation, use the = sign to acquire the minimum value. Anything greater than what's equal to the left side of the Heisenberg equation would then become values that are bigger than the minimum value (anything equal to) The reason why the 2 is multip...
by Jamie_Lin_3I
Mon Sep 26, 2016 10:21 pm
Forum: Empirical & Molecular Formulas
Topic: Chem Workbook Self Test Q4 [ENDORSED]
Replies: 3
Views: 658

Re: Chem Workbook Self Test Q4 [ENDORSED]

Hello Abigail! So the problem is asking for the empirical formula based on the given that Cobalt (339.20g) + Fluorine gas -> compound (996.08) (of unknown chemical formula) We can figure out the mass of fluorine gas by doing: Compound mass - Cobalt mass = fluorine gas mass (law of conservation of ma...

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