Search found 22 matches

by Yoon Lee 2A
Thu Mar 10, 2016 9:43 pm
Forum: *Electrophilic Addition
Topic: The Number of Intermediates for Electrophilic Addition
Replies: 3
Views: 509

The Number of Intermediates for Electrophilic Addition

For the reaction profile of an electrophilic addition reaction, there are two peaks for the two steps/two transition states, and one trough in the graph. I thought this single trough means there is only one intermediate, but for electrophilic addition, there are always two intermediates? Why does th...
by Yoon Lee 2A
Sat Mar 05, 2016 4:16 pm
Forum: *Ketones
Topic: HW 2.27 Numbering the Carbons
Replies: 1
Views: 737

HW 2.27 Numbering the Carbons

2.27 asks to draw a structure of 2,2-dimethyl-3-pentanone. I was wondering why it is numbered as 2,2-dimethyl-3-pentanone instead of 4,4-dimethyl-3-pentanone since the functional group is given the priority (so pentanone should have a lesser number than the methyls)?

Thank you in advanced!
by Yoon Lee 2A
Sat Feb 27, 2016 3:47 pm
Forum: *Alcohols
Topic: Why 4-chloro-3-butanol?
Replies: 2
Views: 478

Why 4-chloro-3-butanol?

I was confused with this last example in lecture on Friday with ClCh2Ch2CHOHCH3 (the OH on the third carbon to the right). Why is it butanol? If the functional group carbon is #1 then isn't it propanol?

Thank you in advanced!
by Yoon Lee 2A
Sun Feb 07, 2016 10:07 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: 14.55 How to determine the anode
Replies: 1
Views: 533

14.55 How to determine the anode

14.55 A 1.0 m NiSO4(aq) solution was electrolyzed by using inert electrodes. Write (a) the cathode reaction; (b) the anode reaction. (c) With no overpotential or passivity at the electrodes, what is the minimum potential that must be supplied to the cell for the onset of electrolysis? How come in th...
by Yoon Lee 2A
Wed Feb 03, 2016 10:25 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: G(naught) vs G
Replies: 1
Views: 358

Re: G(naught) vs G

deltaG is zero when the reaction is at equilibrium. deltaG(naught) is zero when K = 1 because since deltaG(naught) = -RTlnK, when K =1, then lnK = 0, and deltaG(naught) = 0.
by Yoon Lee 2A
Mon Jan 25, 2016 3:33 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 9.83 Homework Problem: using volume to find concentration
Replies: 2
Views: 1039

9.83 Homework Problem: using volume to find concentration

9.83 Hydrogen burns in an atmosphere of bromine gas to give hydrogen bromide gas. (a) What is the standard Gibbs free energy of the reaction H2(g) Br2(g) S 2 HBr(g) at 298 K? (b) If 120. mL of H2 gas at STP combines with a stoichiometric amount of bromine and the resulting hydrogen bromide dissolves...
by Yoon Lee 2A
Sun Jan 24, 2016 3:20 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Knowing when a value is equal to zero
Replies: 2
Views: 414

Re: Knowing when a value is equal to zero

Why isn't delta S surr also zero since it is also a state function?
by Yoon Lee 2A
Sat Jan 23, 2016 7:57 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Homework 9.47 Isothermal/Expansion Problem
Replies: 1
Views: 1913

Homework 9.47 Isothermal/Expansion Problem

9.47 Initially a sample of ideal gas at 323 K occupies 1.67 L at 4.95 atm. The gas is allowed to expand to 7.33 L by two pathways: (a) isothermal, reversible expansion; (b) isothermal, irreversible free expansion. Calculate Stot, S, and Ssurr for each pathway. I solved for the number of moles, n, an...
by Yoon Lee 2A
Wed Jan 20, 2016 8:20 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Concepts about Internal Energy and Entropy
Replies: 1
Views: 193

Concepts about Internal Energy and Entropy

Hello! I was hoping someone could clarify what we learned in lecture today about how internal energy has to be zero in order to figure out what makes a reaction favorable (entropy or enthalpy) and so that q equals -w. Why does internal energy have to be zero? And I am also a bit confused about what ...
by Yoon Lee 2A
Mon Jan 11, 2016 7:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Using Volume of Solution for Calorimetry Calculations
Replies: 1
Views: 401

Using Volume of Solution for Calorimetry Calculations

Hello! Today in lecture, we went over the example with 50.0 mL of 1.0 M HCL and NaOH. We used the volume and density to find mass, but I was wondering why we cannot find the moles of water produced and then convert the moles to grams and then use q = g x Csp x change in temperature? Why do we need t...
by Yoon Lee 2A
Sat Jan 09, 2016 7:48 pm
Forum: Phase Changes & Related Calculations
Topic: Conditions for Standard Enthalpy
Replies: 1
Views: 281

Conditions for Standard Enthalpy

The standard conditions are 25 deg Celsius and 1 atm...how come there is no standard for volume? Is it because volume depends on the numbers of moles of a gas there are?
by Yoon Lee 2A
Wed Dec 02, 2015 2:43 pm
Forum: Calculating the pH of Salt Solutions
Topic: HW 13.97 Finding pH involving CaCO3 and HCl
Replies: 1
Views: 590

HW 13.97 Finding pH involving CaCO3 and HCl

I need help figuring out how to do: 13.97 Two friends go to an all-you-can eat restaurant but eat a little too much and get heartburn. Both return to their rooms and look for a remedy. One friend takes two tablets, each containing 750 mg CaCO3, and the second friend takes 3 teaspoons of milk of magn...
by Yoon Lee 2A
Mon Nov 30, 2015 10:30 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: What is K for 12.69.b?
Replies: 1
Views: 382

What is K for 12.69.b?

12.69 Calculate the pH of each of the following solutions:
(b) 0.055 m AlCl3(aq).

I am pretty sure Al3+ would be an acid...how do we know what K is when [Al(H2O)6]3+ is formed? (and how did we know that [Al(H2O)6]3+ formed and not some other compound like [Al(H2O)3]3+?
by Yoon Lee 2A
Sun Nov 29, 2015 11:04 pm
Forum: Bronsted Acids & Bases
Topic: HW 12.9.c is not a proton transfer?
Replies: 2
Views: 443

HW 12.9.c is not a proton transfer?

I need help putting to words why (c) CH3COOH(aq) + NH3(aq) -> CH3CONH2(aq) + H2O(l) is not considered a proton transfer? It doesn't "look" like it but I need help explaining. Thank you!
by Yoon Lee 2A
Fri Nov 20, 2015 5:18 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Clarification on Acid/Base concepts
Replies: 2
Views: 471

Clarification on Acid/Base concepts

I had a few questions about the concept of acid and bases:

Does H3O+ actually have three hydrogens bonded to the oxygen, or is it just a H+ interacting with the H2O?

And, I think this might have been mentioned in class, but are Lewis acids/bases always Bronsted acids/bases?

Thank you!
by Yoon Lee 2A
Tue Nov 10, 2015 9:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW problem 11.7c: Calculate K given initial Pressure in bar
Replies: 1
Views: 252

HW problem 11.7c: Calculate K given initial Pressure in bar

For this problem, I made an ICE box using the equation X2 <-> 2X since the diatomic gas is becoming two "X"s. However, I keep on getting an answer different to the textbook...help please! Thank you!
by Yoon Lee 2A
Mon Nov 02, 2015 7:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Comparing Equilibrium Concentrations
Replies: 1
Views: 229

Comparing Equilibrium Concentrations

In the equation N2 + 3H2 <-> 2NH3, how come the equilibrium concentration for hydrogen is not three times more than that of nitrogen? Are the equilibrium concentrations of the reactants and products in anyway related to each other through the coefficients?(ie. would equilibrium concentration of N2 b...
by Yoon Lee 2A
Wed Oct 28, 2015 7:00 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Energy difference between 2s and 2p based on nuclear charge
Replies: 1
Views: 698

Energy difference between 2s and 2p based on nuclear charge

Hello!

How come the energy difference between the 2s and 2p orbitals decreases as effective nuclear charge decreases? And how come when we "add" two 2s atomic orbitals we get a bonding sigma molecular orbital of lower energy rather than higher? Does it have to do with stability?

Thank you!
by Yoon Lee 2A
Fri Oct 23, 2015 10:36 am
Forum: Hybridization
Topic: Textbook Problem 3.21C
Replies: 1
Views: 877

Re: Textbook Problem 3.21C

Hello! Te has 6 valence electrons. (It is in the same group as oxygen.) However, Te^2- is an anion with two more electrons than the neutral Te. Therefore, it has 6 + 2 electrons or 8 electrons. This make Te^2- have the same configuration as the element two spaces next to Te (and thus, two electrons ...
by Yoon Lee 2A
Wed Oct 14, 2015 6:34 pm
Forum: Ionic & Covalent Bonds
Topic: More than Octect
Replies: 5
Views: 986

More than Octect

Hello,

Sulfur can have more than eight electrons because there are 3d orbitals available...so do the extra electrons on sulfur go into the 3d orbitals? I thought that we filled in the 4s orbital first?

Thank you!
by Yoon Lee 2A
Wed Oct 07, 2015 9:03 am
Forum: Quantum Numbers and The H-Atom
Topic: Chapter 2, Problem 19, part A # of values for l
Replies: 1
Views: 395

Chapter 2, Problem 19, part A # of values for l

Hello! Can someone explain to me why the answer to this problem is seven? (2.19.a) "How many values of the quantum number l are possible when n =7? " I thought it would be four because in the seventh row, the electron can be in s, p, d, or f which is 0, 1, 2, 3...four possible values for q...
by Yoon Lee 2A
Mon Sep 28, 2015 9:41 pm
Forum: Properties of Light
Topic: Hw 1.7
Replies: 2
Views: 491

Re: Hw 1.7

Hi, Kayla!

I also got 150 pm! For some reason, the back of the book says nm, but the problem even asks for pm, so I am pretty sure we are correct! :)

-Yoon

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