Search found 35 matches

by Jose_Arambulo_2I
Thu Mar 16, 2017 10:38 pm
Forum: Calculating Work of Expansion
Topic: winter 2015 final Q3 C
Replies: 1
Views: 321

winter 2015 final Q3 C

To calculate the volume after inhalation, why are you supposed to add the initial volume, 2.500L, by 0.705L. I don't understand how 0.705L is the delta V. If anything, shouldn't the delta v be 0.705L-0.667L? Because that'd give us the change in volume that accompanies the change in temperature.
by Jose_Arambulo_2I
Mon Mar 13, 2017 7:18 pm
Forum: *Alcohols
Topic: Functional Groups and Double/Triple Bonds
Replies: 1
Views: 535

Functional Groups and Double/Triple Bonds

Since we won't be tested on organic molecules with more than 1 functional group, does that mean that we won't be asked to name organic compounds with both a double (or triple) bond and a functional group?
by Jose_Arambulo_2I
Tue Mar 07, 2017 9:34 pm
Forum: *Ethers
Topic: Introduction to Organic Chemistry Textbook Page 69
Replies: 3
Views: 656

Re: Introduction to Organic Chemistry Textbook Page 69

That is because there are two methyl groups, one attached to carbon 1 and the other attached to carbon 2.
by Jose_Arambulo_2I
Tue Mar 07, 2017 9:31 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Intro to Organic Chemistry HW Section 4.3 #29 and 30
Replies: 2
Views: 390

Re: Intro to Organic Chemistry HW Section 4.3 #29 and 30

On page 154 of the organic textbook, it says that a reaction will only occur at room temperature if the activation energy is about 80 kJ/mol or less.
by Jose_Arambulo_2I
Wed Mar 01, 2017 2:25 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Catalyst
Replies: 6
Views: 635

Re: Catalyst

Furthermore, a catalyst lowers the free energy of activation by lowering the energy required to break bonds (decreases standard enthalpy of activation) and puts the reactants closer together and in their correct orientations (increases standard entropy of activation).
by Jose_Arambulo_2I
Wed Mar 01, 2017 12:45 am
Forum: *Electrophilic Addition
Topic: Electrophilic addition reaction of HBr and Propene
Replies: 2
Views: 373

Electrophilic addition reaction of HBr and Propene

In the first step of this reaction mechanism, does the hydrogen have to form a bond with carbon 3? Because I don't see why it couldn't also do the same with carbon 2 instead. The reaction can be found on pg 152 in the organic textbook.
by Jose_Arambulo_2I
Mon Feb 27, 2017 11:52 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: 4.30
Replies: 1
Views: 251

4.30

If an organic reaction has an activation energy of 125 kJ/mol, how can you be sure that the reaction will not occur at room temperature?
by Jose_Arambulo_2I
Mon Feb 27, 2017 2:19 am
Forum: *Electrophiles
Topic: Difference Nucleophile and Electrophile
Replies: 2
Views: 307

Re: Difference Nucleophile and Electrophile

A nucleophile wants anything positively charged, whereas a an electrophile wants electrons. This is directly related to lewis acids and bases; it's basically another way to refer to them. For example a general chemist might call NH3 a a base because it's a proton acceptor and it can donate its lone ...
by Jose_Arambulo_2I
Fri Feb 24, 2017 2:54 am
Forum: First Order Reactions
Topic: 15.23 (c)
Replies: 3
Views: 447

Re: 15.23 (c)

This is because the rate that B increases is equal to the rate that A decreases. I currently don't have the book on me, but it's probably doubled due to the rxn's stoichiometric coefficients
by Jose_Arambulo_2I
Thu Feb 23, 2017 5:20 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Mechanisms with equilbrium
Replies: 1
Views: 249

Mechanisms with equilbrium

If you're given a two-step mechanism, where the first step is in a state of equilibrium, does that immediately make that step the fast step since pre equilbrium assumes that the equilibrium reaction comes before the slow step? Or do you have to compare the rate constants of each step to determine th...
by Jose_Arambulo_2I
Thu Feb 23, 2017 5:15 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-Equilibrium Approach
Replies: 2
Views: 309

Re: Pre-Equilibrium Approach

Yes you're right. If the slow step was the first step, and there were no intermediates on the reactant side, then that rate law should be the same as the experimental rate law.
by Jose_Arambulo_2I
Wed Feb 22, 2017 4:10 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 2 Prep answers
Replies: 2
Views: 422

Quiz 2 Prep answers

Will the answers to the quiz 2 practice questions be posted?
by Jose_Arambulo_2I
Sun Feb 19, 2017 2:16 am
Forum: First Order Reactions
Topic: Quiz 2 prep #3
Replies: 4
Views: 457

Quiz 2 prep #3

This question gives the reaction N2O---> N2 + O2 and it gives the rate constant r*k[N2O]. Would this be first order because of the given rate law, or do we have to balance it then add an exponent (in this case 2) to the concentration?
by Jose_Arambulo_2I
Tue Feb 14, 2017 4:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: State Functions
Replies: 1
Views: 243

State Functions

Hi all,

Can someone explain why E isn't a state function? We're always adding them and/or looking at its final and initial states, so I don't understand why they would,t be state functions.
by Jose_Arambulo_2I
Tue Feb 14, 2017 4:31 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Midterm 2014 Q5B
Replies: 1
Views: 340

Midterm 2014 Q5B

This question reads:
"Which has a higher molar entropy value at 25 degrees Celsius: benzene or hexane?"

Is the answer hexane because it has single bonds and can rotate (giving it more orientations), while benzene is basically "stuck" in its ring shape?
by Jose_Arambulo_2I
Sun Feb 12, 2017 12:31 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cells and water
Replies: 1
Views: 285

Galvanic Cells and water

I have a quick question about designing galvanic cells. Once you figure out the half reactions and choose the cathode and anode sides, is it just convention to leave out water even though it shows up in one or both of the half reactions? Or is it left out for the same reason why it's left out in equ...
by Jose_Arambulo_2I
Fri Feb 10, 2017 2:31 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Inert Electrodes
Replies: 2
Views: 371

Inert Electrodes

I was wondering if I could have some clarification on the purpose of using inert electrodes. Also, how come sometimes an inert electrode will be on both the cathode and anode side, while other times it'd only be on one side?
by Jose_Arambulo_2I
Sat Feb 04, 2017 12:57 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7750
Views: 1069357

Re: Post All Chemistry Jokes Here

Hey baby, why don't you come to my place so I can show you the exponential growth of my natural log.
by Jose_Arambulo_2I
Wed Feb 01, 2017 2:42 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Problem 8.9
Replies: 3
Views: 440

Re: Problem 8.9

You use the conversion factor 101.325J/1 L•atm. Heres the link to Dr. Lavelles explanation viewtopic.php?f=128&t=1898. Hope this helps!
by Jose_Arambulo_2I
Sun Jan 29, 2017 6:37 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.13
Replies: 5
Views: 560

Re: 9.13

Yeah, I'm also confused as to why the solution manual uses delta s= nRln(T2/T1) rather than delta s=nCln(T2/T1) when the temperature change occured.
by Jose_Arambulo_2I
Sun Jan 29, 2017 3:21 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G and delta G naught
Replies: 1
Views: 11056

Delta G and delta G naught

Hello! I'm just a little confused about these two things. From my understanding, the naught refers to standard conditions, making me think that the only difference between the two values are that delta G naught is the change in free energy in 1 atm and 25 degrees Celsius and delta G is just the chan...
by Jose_Arambulo_2I
Mon Jan 23, 2017 1:47 am
Forum: Phase Changes & Related Calculations
Topic: Open, Closed, and Isolated Systems
Replies: 8
Views: 775

Re: Open, Closed, and Isolated Systems

I think a constant pressure calorimeter would be an example of an open system because the volume can change. (Open system=stuff can be added or removed from system). It shouldn't be a closed system because volume shouldn't change, and it definitely cannot be isolated.
by Jose_Arambulo_2I
Wed Jan 11, 2017 10:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Posts
Replies: 23
Views: 2660

Posts

Do weekly posts still affect our grades for Chem 14B?
by Jose_Arambulo_2I
Wed Nov 30, 2016 1:41 am
Forum: Polyprotic Acids & Bases
Topic: 12.81
Replies: 1
Views: 383

12.81

Hello! So in this question we're asked to find the pH of a diprotic acid, like H2CO3. I understand that two steps take place in which a proton is donated in each step, but I do not understand why answer book says that "the second ionization can be ignored" since the the second ka is smalle...
by Jose_Arambulo_2I
Mon Nov 21, 2016 6:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Adding 2 equilibrium reactions
Replies: 1
Views: 290

Adding 2 equilibrium reactions

When you're adding two equilibrium reactions, such as
2BrCl=Br2+Cl K=377
H2+Cl2=2HCl K=4E31

Why do you multiply their K's rather than just adding them?
by Jose_Arambulo_2I
Wed Nov 16, 2016 8:47 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Identifying Polydentates? [ENDORSED]
Replies: 8
Views: 1032

Re: Identifying Polydentates? [ENDORSED]

It's not just the number of atoms with lone pairs, it also considers shape and type of bond. For example, if the lone pair atom is bonded with a double or triple bond, then they won't have the ability to bend to form chelates, preventing them from being polydentate. Single bonds, however, allow this...
by Jose_Arambulo_2I
Thu Nov 10, 2016 11:07 am
Forum: Naming
Topic: 17.31 d
Replies: 1
Views: 257

17.31 d

This problem asks for the formula for sodium bisoxalato(diaqua)ferrate(III), and I wrote Na[Fe(C2O4)2(OH2)2], but in the solution manual the aqua and the oxalato are switched in position. Why is this the case? I thought that the ligands are placed alphabetically based on their symbols?
by Jose_Arambulo_2I
Tue Nov 08, 2016 4:59 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: MO Diagram difference
Replies: 1
Views: 251

MO Diagram difference

I'm still unclear as to why the sigma p orbitals and pi p orbitals switch depending on nuclear charge. What exactly causes this to take place?
by Jose_Arambulo_2I
Wed Nov 02, 2016 12:15 am
Forum: Hybridization
Topic: Fall Quiz 2 2014 prep Question 3 [ENDORSED]
Replies: 1
Views: 245

Fall Quiz 2 2014 prep Question 3 [ENDORSED]

This question asks for the hybrid orbitals involved both in the C-C sigma bonds and C-H pi bonds in benzene. I know that each carbon has the hybridization of sp2 because it has three regions of electron density, but how do I find the hybrid orbitals for specific bonds, like what question 3 asks for?
by Jose_Arambulo_2I
Thu Oct 27, 2016 2:15 pm
Forum: Resonance Structures
Topic: N2O Resconance
Replies: 1
Views: 608

N2O Resconance

I hope it's fine for me to ask a quiz question. How exactly would you draw the lewis structure for N2O with resonance strucutres? I made oxygen the central atom, but I only realized that was a mistake after I turned in the quiz. So how should I approach this problem correctly?
by Jose_Arambulo_2I
Fri Oct 21, 2016 1:34 am
Forum: Properties of Electrons
Topic: Forces and Potential Energy in Atoms [ENDORSED]
Replies: 1
Views: 544

Forces and Potential Energy in Atoms [ENDORSED]

Hi, I was wondering how exactly you'd do this problem The electron in a hydorgen atom is initially at a distance 2.12 A from the proton, and then moves in the +x direction to a distance 0.529 A from the proton. Calculate the magnitude of the force on the electron at each seperation Calculate the cha...
by Jose_Arambulo_2I
Mon Oct 17, 2016 11:46 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: d and s orbitals
Replies: 2
Views: 298

d and s orbitals

Hi, I just had a question about the order you're supposed to fill the s and d orbitals. Throughout high school, I was taught that the 4s orbital would be filled before the 3d orbital, but the notes and hw answers say otherwise. For example on question 2.43, it says that the configuration of Ag would...
by Jose_Arambulo_2I
Thu Oct 13, 2016 12:07 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Homework Problem 2.39 Issue
Replies: 4
Views: 599

Re: Homework Problem 2.39 Issue

Good question! What you forget to consider was the spins and the orbitals used in the diagrams. Oxygen diagram is the only ground state example not only because it has 6 electrons, but also because the electrons are distributed in the most stable manner possible, taking into account hund's rule and ...
by Jose_Arambulo_2I
Fri Oct 07, 2016 1:42 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Quiz Preparation #5 [ENDORSED]
Replies: 1
Views: 376

Quiz Preparation #5 [ENDORSED]

Hi, I'm just a tad confused with the 5th problem on the quiz 1 preparation (pg. 28). In the problem, it states that the bowling ball's speed is "2.35+/-0.1ms^-1." What then would the delta v value be if I'm trying to solve for delta p?
by Jose_Arambulo_2I
Mon Sep 26, 2016 11:56 pm
Forum: Limiting Reactant Calculations
Topic: Multiple Limiting Reactants? [ENDORSED]
Replies: 4
Views: 1719

Re: Multiple Limiting Reactants? [ENDORSED]

Assuming this is a single-stepped reaction, I'd say there can't be more than one limiting reactant because once one reactant is "used up," the reaction will not continue further.

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