Search found 31 matches

by Stefanie Bui 1J
Fri Mar 11, 2016 5:26 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: 2015 Winter Final Question 3C
Replies: 1
Views: 515

Re: 2015 Winter Final Question 3C

Before inhalation, you have the volume of 2.500 L. After inhalation, you take in more air causing the volume to get bigger. So you add the 2 volumes together to get the total volume after inhalation!

Hope this helps!
by Stefanie Bui 1J
Mon Mar 07, 2016 12:42 am
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Anti vs Gauche
Replies: 1
Views: 861

Re: Anti vs Gauche

Gauche has a dihedral angle of +60o degrees and Anti has a dihedral angle of +180o degrees.

Hope this helps! You can also refer to page 106 in the orange 'Intro to Chem' book. It has a clear picture of the difference between a Gauche conformation and an Anti conformation.
by Stefanie Bui 1J
Mon Feb 29, 2016 11:06 pm
Forum: *Alkenes
Topic: Geometric isomers (ex 1.27)
Replies: 1
Views: 312

Re: Geometric isomers (ex 1.27)

Priority is based off of the atomic number. So since F has a higher atomic number than the C in CH3, F has the higher priority on that particular carbon atom. On the other carbon atom, Br has a higher atomic number than the C in the H 3 CH 2 C molecule so Br has the higher priority. Therefore, when ...
by Stefanie Bui 1J
Mon Feb 29, 2016 10:23 pm
Forum: *Alkanes
Topic: Self-Test 4.1A
Replies: 1
Views: 243

Self-Test 4.1A

Hello! Could someone please explain what an alkyl carbanion and what an aryl carbanion is? Thanks so much!
by Stefanie Bui 1J
Tue Feb 23, 2016 5:45 pm
Forum: *Alkanes
Topic: Single bond vs. Double Bond
Replies: 3
Views: 2890

Re: Single bond vs. Double Bond

I'm not sure if this is right but because unsaturated hydrocarbons have double bonds/triple bonds..these bonds create kinks that will cause them to be liquids at room temperature with weak intermolecular forces. Since saturated hydrocarbons have only single bonds, they don't have those kinks, allowi...
by Stefanie Bui 1J
Thu Feb 18, 2016 7:00 pm
Forum: Second Order Reactions
Topic: quiz 2 practice winter 2014
Replies: 2
Views: 501

Re: quiz 2 practice winter 2014

You ignore the [A] graph because it is not linear. Since the graph is curved, you know that the reaction is not zero order. To be zero order, the graph must be linear and have a negative slope. Since the 1/[A] graph has a positive slope and is linear, it follows the rules to be a graph of a second o...
by Stefanie Bui 1J
Wed Feb 17, 2016 11:11 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Spontaneous and energetically stable
Replies: 2
Views: 815

Re: Spontaneous and energetically stable

If the energy of the products is lower than the energy of the reactants than the reaction is spontaneous/energetically favorable because then delta G would be negative.

Hope this helps!
by Stefanie Bui 1J
Tue Feb 09, 2016 10:48 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 2015 Midterm #7
Replies: 2
Views: 395

Re: 2015 Midterm #7

Since this is a concentration cell problem, E0 will be zero. This will always be the case when dealing with concentration cells.
by Stefanie Bui 1J
Tue Feb 09, 2016 6:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Midterm 2014 Q7: galvanic cell
Replies: 1
Views: 289

Re: Midterm 2014 Q7: galvanic cell

Galvanic cells tend to prefer a standard cell potential that is positive. So if they give you no indication of which one is the cathode or anode, you get to choose (that is what a UA told me)! So with that said, you would switch the Zinc equation, so that the E 0 when calculated, will be a positive ...
by Stefanie Bui 1J
Tue Feb 09, 2016 3:49 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Standard cell potential vs cell potential
Replies: 3
Views: 737

Re: Standard cell potential vs cell potential

E is usually called the cell potential, and E0 is usually referred to as the potential difference or standard cell potential!

Hope this helps!
by Stefanie Bui 1J
Mon Feb 08, 2016 5:27 pm
Forum: Calculating Work of Expansion
Topic: When to use which formula
Replies: 3
Views: 494

Re: When to use which formula

w=-nRTln(V2/V1) is usually associated with a problem that asks for the work when it is reversible and isothermal.
w=-pexΔv is usually associated with a problem that asks for the work when it is irreversible.
by Stefanie Bui 1J
Sun Feb 07, 2016 11:06 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm 2013 Q7
Replies: 1
Views: 337

Midterm 2013 Q7

For this problem, it says that the ΔG0 could also be found by using the equation ΔG0 = -RT ln K and that the answer would be K = 9.2 x 10-72. When doing it with that equation, I kept getting 1.4 x 10-72 as the answer. Is there a possible error in the answer?
by Stefanie Bui 1J
Wed Feb 03, 2016 12:14 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: HW 14.35 Possible Solution Manual Error?
Replies: 3
Views: 520

HW 14.35 Possible Solution Manual Error?

In homework problem 14.35, it asks to find the equilibrium constant for In 3+ (aq) + U 3+ (aq) --> In 2+ (aq) + U 4+ (aq). To do this I used the equation ln K = n r FE 0 / RT. In the solution manual, it says that the number n is equal to 2. But when I looked in the appendix, it appears that both hal...
by Stefanie Bui 1J
Tue Feb 02, 2016 5:22 pm
Forum: Balancing Redox Reactions
Topic: Add H+ or OH-
Replies: 5
Views: 2348

Re: Add H+ or OH-

If the redox reaction is in an acidic solution, you will balance the O atoms by adding H 2 O and then balance the H atoms by adding H + . If the redox reaction is in a basic solution, you will balance the H atoms by adding (for each H atom needed) one H 2 O molecule to the side of each equation that...
by Stefanie Bui 1J
Wed Jan 27, 2016 11:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Calculating Gibbs Free Energy
Replies: 1
Views: 542

Re: Calculating Gibbs Free Energy

To find ΔH and ΔS you would use the values given and subtract the (sum of the products) - (the sum of the reactants). Then, since ΔH is in kj/mol and ΔS is j/k*mol you will have to convert the ΔS (entropy) value into kJ before using the ΔG = ΔH - TΔS equation. Once you convert the ΔS value into kJ, ...
by Stefanie Bui 1J
Tue Jan 19, 2016 4:59 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy equations?
Replies: 1
Views: 299

Re: Enthalpy equations?

I believe that there are 3 ways to find the enthalpy, delta H. The 3 ways are Hess's Law, bond enthalpies, and standard enthalpy of formation (sum of standard enthalpy of formation of the products - sum of the standard enthalpy of formation of the reactants)
by Stefanie Bui 1J
Tue Jan 12, 2016 11:02 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: When to use C=5/2R or C=3/2R
Replies: 7
Views: 1975

Re: When to use C=5/2R or C=3/2R

In this equation, R stands for the constant 8.3145 J*K-1*mol-1.
by Stefanie Bui 1J
Thu Jan 07, 2016 9:56 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy of Sublimation
Replies: 3
Views: 493

Re: Enthalpy of Sublimation

I think this is because the heat is being used to break the bonds, not increase the temperature.
by Stefanie Bui 1J
Tue Dec 01, 2015 1:05 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Solution Manual Error
Replies: 1
Views: 294

Solution Manual Error

For HW problem 12.59d, the solution manual says that the percentage protonation should be 2.5% but I've done the calculation 100(1.1x10-4 / .0073) about 3 times on my calculator and I keep getting 1.5%.

I think the solution manual is wrong and the answer should be 1.5%! Can someone confirm this?
by Stefanie Bui 1J
Fri Nov 27, 2015 4:50 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Endothermic and Exothermic Reactions
Replies: 3
Views: 704

Re: Endothermic and Exothermic Reactions

So if the enthalpies (ΔH) are given, an exothermic reaction would have a negative ΔH and an endothermic reaction would have a positive ΔH.
by Stefanie Bui 1J
Mon Nov 16, 2015 6:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding Q
Replies: 1
Views: 336

Re: Finding Q

The numerator would be [BrCl] 2 . To find the Q when giving an equation aA + bB <--> cC + dD, you would put [products] / [reactants]. The stoichiometric coefficients of the balanced equation is the power that u will raise the concentration of each molecule to. The formula to find Q would look someth...
by Stefanie Bui 1J
Wed Nov 11, 2015 5:20 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: When to use bi-, tri- vs. bis-, tris-?
Replies: 3
Views: 3200

Re: When to use bi-, tri- vs. bis-, tris-?

In addition if the ligand has di-, tri-, tetra-, etc. in its name, you would use those prefixes. For example ethylenediamine has the prefix di- in its name, so u would use the prefixes bis-, tris-, tetrakis-, etc.
by Stefanie Bui 1J
Wed Nov 04, 2015 2:03 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Unpaired Electrons in Molecular Orbitals
Replies: 5
Views: 1687

Re: Unpaired Electrons in Molecular Orbitals

Yes! Sorry about that! I chose the wrong picture when looking it up. ( I just edited it).
Since NO is a heterodiatomic molecule, you would use the MO diagram for z<8.
by Stefanie Bui 1J
Tue Nov 03, 2015 1:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Why is H2CBr2 polar?
Replies: 4
Views: 575

Re: Why is H2CBr2 polar?

Although H2CBr2 is tetrahedral in shape, it is polar because the atoms bounded to the central atom are not all the same atom type. Tetrahedral molecules are only nonpolar when all the atoms bounded to the central atom are of the same species.
by Stefanie Bui 1J
Sat Oct 31, 2015 2:11 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Unpaired Electrons in Molecular Orbitals
Replies: 5
Views: 1687

Re: Unpaired Electrons in Molecular Orbitals

You would determine which molecular orbital has an unpaired electron by drawing & filling in the MO chart and looking at which molecular orbital the unpaired electron occupies in the end. For example, for the NO molecular orbital diagram you know that Nitrogen has 5 valence electrons and O has 6...
by Stefanie Bui 1J
Mon Oct 26, 2015 5:40 pm
Forum: Bond Lengths & Energies
Topic: Stronger Ionic/Covalent Bonds
Replies: 3
Views: 994

Stronger Ionic/Covalent Bonds

How would we figure out which ionic/covalent bond is stronger without an electronegativity chart?
I've been having trouble figuring out which compound would have a higher ionic/covalent character.

For example, would PCl5 or PF5 have a higher covalent bond?
by Stefanie Bui 1J
Tue Oct 20, 2015 2:11 pm
Forum: Resonance Structures
Topic: Which Resonance Structure to Use?
Replies: 2
Views: 493

Re: Which Resonance Structure to Use?

In addition to what Srivinay_Irrinki said, to find out which resonance structure makes a bigger contribution to the resonance hybrid, it would be necessary to find out the formal charges of each structure. Whichever structure that has a formal charge closer to 0, will make the bigger contribution, s...
by Stefanie Bui 1J
Fri Oct 16, 2015 8:49 pm
Forum: Lewis Structures
Topic: Molecular Shapes
Replies: 1
Views: 271

Molecular Shapes

Hi there! Can someone clarify why the angles between certain elements and their bonds isn't equal to 360 divided by the number of extensions from the central atom? Trigonal planar makes sense to me because 360 divided by 3 is equal to 120, but for tetrahedral I don't understand why the angles aren't...
by Stefanie Bui 1J
Fri Oct 09, 2015 12:03 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Thorium
Replies: 1
Views: 422

Thorium

Hi guys! I have a quick question. For Thorium, the configuration stated on the periodic table of elements is [Rn] 6d2 7s2.
I know that Radon has an electron configuration of [Xe] 4f14 5d10 6s2 6p6. Why is the electron configuration of Thorium not [Rn] 5f2 7s2. Doesn't the 5f come before 6d?
by Stefanie Bui 1J
Fri Oct 02, 2015 4:17 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect
Replies: 5
Views: 723

Re: Photoelectric Effect

In addition, if the photons from the light source do not have enough energy to eject an electron from the metal of the surface, increasing the intensity will not help. No matter the intensity, if there is not enough energy the light will not be absorbed.

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