Search found 28 matches

by Austin Vo 1K
Sun Mar 13, 2016 7:18 pm
Forum: General Rate Laws
Topic: 2012 #7B
Replies: 2
Views: 510

Re: 2012 #7B

The reaction has a faster rate at the catalyzed step than the uncatalyzed step. Therefore dividing the two rates (essentially their rate constants) will show you how much faster.
by Austin Vo 1K
Mon Mar 07, 2016 12:01 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question 1A on 2011 Final
Replies: 2
Views: 443

Re: Question 1A on 2011 Final

There might be an error. You're right; you should calculate the q needed to raise the temperature to 100oC, the energy needed to vaporize, and the energy released when its cooled back to 25oC.
by Austin Vo 1K
Fri Mar 04, 2016 1:23 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Chapter 4 #29 and #30
Replies: 1
Views: 343

Re: Chapter 4 #29 and #30

I'm not sure about your first question; I would assume that you have to know the reaction (or it's given that the reaction is exothermic or endothermic) through experimental analysis. With regards to 4.30, it says on page 154 of Introduction to Organic Chemistry that reactions with activation energi...
by Austin Vo 1K
Sun Feb 28, 2016 6:33 pm
Forum: *Nucleophiles
Topic: Nucleophile and electrophile
Replies: 1
Views: 418

Re: Nucleophile and electrophile

Think in terms of electrostatics. Chlorine is more electronegative than either carbon or hydrogen so the flow of electrons is from the single covalent bond between chlorine and carbon to the chlorine atom, thus chlorine is "broken" off.
by Austin Vo 1K
Sun Feb 28, 2016 6:28 pm
Forum: *Alkanes
Topic: "Tert-" Prefix
Replies: 5
Views: 582

Re: "Tert-" Prefix

Similar to what was stated earlier, tert- means that there is a carbon that is bonded to three other carbons. It can be part of the name given to different types of isomers with this structure. In naming different substances, tert- usually appears as part of a common name as in the "tert-butyl&...
by Austin Vo 1K
Sun Feb 21, 2016 7:39 pm
Forum: Dipole Moments
Topic: which has the largest dipole moment?
Replies: 1
Views: 3297

Re: which has the largest dipole moment?

Isomer (3) FHC=CFH would have the largest dipole moment. Isomer (2) is a trans-isomer and due to its symmetry has no net dipole moment. Isomer (3) (which is a cis-isomer) has a larger dipole moment than isomer (1) FFC=CHH because the two fluorine atoms are bonded to separate carbon atoms. The p-orbi...
by Austin Vo 1K
Sun Feb 14, 2016 5:18 pm
Forum: General Rate Laws
Topic: Homework 15.19
Replies: 1
Views: 414

Re: Homework 15.19

You must convert all of the concentrations into mol/L when you use the integrated rate law if you want the final answer to be in mol L-4S-4.
by Austin Vo 1K
Sun Feb 07, 2016 6:04 pm
Forum: Balancing Redox Reactions
Topic: balancing half reactions
Replies: 3
Views: 466

Re: balancing half reactions

Usually the question would tell you whether the reaction takes place in an acidic or a basic solution. If it does not, I would just balance the half reactions in acidic solution.
by Austin Vo 1K
Sun Jan 31, 2016 2:20 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Calculating Gibbs Free Energy HW #11.17
Replies: 1
Views: 501

Re: Calculating Gibbs Free Energy HW #11.17

I got the same answer as you. I believe this an error in the solutions manual.
by Austin Vo 1K
Sun Jan 24, 2016 1:14 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW 8.49
Replies: 2
Views: 389

Re: HW 8.49

I'm guessing that if there's no temperature given, just assume that the reaction takes place at room temperature (25oC or 298K).
by Austin Vo 1K
Sun Jan 17, 2016 6:18 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.73 HW Question
Replies: 1
Views: 265

Re: 8.73 HW Question

The only way to tell which bonds you must account for is by drawing out the Lewis structures for each substance and then determining which bonds are broken and formed. For 8.73 (a) you have to account for three triple bonds between carbons due to the coefficient 3 in front of C2H2.
by Austin Vo 1K
Sun Jan 17, 2016 6:13 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Finding change in internal energy using PV=nRT equation
Replies: 3
Views: 1672

Re: Finding change in internal energy using PV=nRT equation

I'm guessing that they may have left out the information for the temperature at which the reaction took place in the textbook. Usually, the temperature would be given in the problem.
by Austin Vo 1K
Fri Jan 08, 2016 10:26 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific Heat Capacity-formula
Replies: 2
Views: 1046

Re: Specific Heat Capacity-formula

Assuming that you are using this formula to calculate how much heat has been supplied to a substance, you would multiply the number of moles of the substance (would be given in the question) by the molar heat capacity and the change in temperature (Final temperature-Initial Temperature).
by Austin Vo 1K
Sat Dec 05, 2015 2:16 pm
Forum: *Titrations & Titration Calculations
Topic: 2010 Final Q7 Henderson-Hasselbalch Equation
Replies: 4
Views: 668

Re: 2010 Final Q7 Henderson-Hasselbalch Equation

I just had another question regarding this same problem. In the beginning of part b, it is found that the moles of CH3COOH is equal to 2.5x10^-3 mol. However, further down in part b when the answers show how to get the molarity of CH3COOH, they use 1.50x10^-3 moles of CH3COOH. I was just wondering ...
by Austin Vo 1K
Sun Nov 29, 2015 2:46 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Problem 12.39
Replies: 2
Views: 463

Re: Problem 12.39

For the first pKa, I meant (CH3)2NH2+
by Austin Vo 1K
Sun Nov 29, 2015 2:44 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Problem 12.39
Replies: 2
Views: 463

Re: Problem 12.39

To find the other two pK a , you would have to look at the pK b of their corresponding conjugate bases and subtract that from 14 (pK w ). For pK a of (CH 3 ) 2 +, look at the pKb of dimethylamine (3.27) and subtract from 14 (14-3.27=10.73). For the pK a of +NH 3 OH, subtract 7.97 (pK b of hydroxylam...
by Austin Vo 1K
Sun Nov 22, 2015 12:00 pm
Forum: Polyprotic Acids & Bases
Topic: Determining what a Polyprotic Acid and Base is
Replies: 1
Views: 339

Re: Determining what a Polyprotic Acid and Base is

The answer to your question is yes. Polyprotic acids are acids that releases more than one proton per molecule of acid while polyprotic bases are bases that accept more than one proton per molecule of base. To continue this definition, polyprotic acids and bases will have more than one dissociation ...
by Austin Vo 1K
Sun Nov 15, 2015 5:58 pm
Forum: Naming
Topic: Ambiguity in naming?
Replies: 1
Views: 295

Re: Ambiguity in naming?

I've noticed this irregularity as well. Based on what I learned from my discussion, yes, you should put the ligands in alphabetical order (ignore prefixes such as di- or tri- when doing so). I would do that just to be safe.
by Austin Vo 1K
Sun Nov 08, 2015 7:46 pm
Forum: Naming
Topic: Naming and oxidation number
Replies: 2
Views: 455

Re: Naming and oxidation number

In this case SO4 has a charge of 2-, NH3 has no charge, and the whole ion complex has a total charge of 1+. Therefore Cobalt has an oxidation number of 3+
by Austin Vo 1K
Sun Nov 08, 2015 7:42 pm
Forum: Naming
Topic: Naming and oxidation number
Replies: 2
Views: 455

Re: Naming and oxidation number

The oxidation number of cobalt is 3+. The name of the ion would be pentaamminesulfatocobalt(III) ion.
by Austin Vo 1K
Sun Nov 01, 2015 10:39 am
Forum: Lewis Structures
Topic: Electron Configuration
Replies: 1
Views: 270

Re: Electron Configuration

For this cation, the two electrons are removed from the orbital that is higher in energy. In this case, 4s is higher in energy than 3d so two electrons are removed from 4s and not 3d.
by Austin Vo 1K
Fri Oct 23, 2015 8:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dichloromethane polarity
Replies: 1
Views: 4590

Re: Dichloromethane polarity

Dichloromethane can only be a polar molecule. Although the Lewis structure might suggest that the dipole moments cancel each other out (which is false even though it appears that way if you draw chlorine /hydrogen directly opposite from each other), you have to refer to the molecular shape, which is...
by Austin Vo 1K
Mon Oct 19, 2015 12:13 am
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 1
Views: 271

Re: Lewis Structures

Generally elements with lower ionization energy are in the center of Lewis structures. Hence, the carbon atoms are located in the center of the structure.
by Austin Vo 1K
Mon Oct 19, 2015 12:06 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Spins
Replies: 3
Views: 551

Re: Electron Spins

My TA said that the electrons are not actually spinning and it simply shows that electrons must first fill empty orbitals before filling an orbital shared another electron.
by Austin Vo 1K
Sun Oct 11, 2015 1:43 am
Forum: Balancing Chemical Reactions
Topic: Writing formulas with gases and metals
Replies: 2
Views: 520

Re: Writing formulas with gases and metals

Since it has a completed valence electron shell, H2 is more stable than a single hydrogen atom existing by itself. Similarly nitrogen, oxygen, chlorine and iodine usually exist as diatomic molecules in the gaseous form. Co would be written as is with (s) indicating it as a solid.
by Austin Vo 1K
Sun Oct 04, 2015 10:49 pm
Forum: SI Units, Unit Conversions
Topic: Preference of Units [ENDORSED]
Replies: 2
Views: 574

Re: Preference of Units [ENDORSED]

It should be acceptable since it means the same.
by Austin Vo 1K
Fri Oct 02, 2015 2:56 am
Forum: Photoelectric Effect
Topic: Clarificaton on Equation for Energy Emitted
Replies: 2
Views: 455

Clarificaton on Equation for Energy Emitted

If we use E=-hR/(n^2) to calculate the energy emitted when an electron makes a transition from n=2 to n=4 (transition from lower to higher principle quantum level) in a hydrogen atom, does the negative sign remain in the calculation?
by Austin Vo 1K
Sun Sep 27, 2015 11:59 pm
Forum: *Black Body Radiation
Topic: Black Body
Replies: 3
Views: 642

Re: Black Body

So does this hypothetical material actually exist? No, right?

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