Search found 26 matches

by Tiffany Chen 2E
Sat Mar 12, 2016 9:14 pm
Forum: *Electrophiles
Topic: General Question about Nucleophiles vs. Electrophiles
Replies: 2
Views: 669

Re: General Question about Nucleophiles vs. Electrophiles

Generally, nucleophiles will also have lone pairs or double bonds as electron-rich regions. Electrophiles, on the other hand, will have open valences or be missing an electron, as they are electron-deficient.
by Tiffany Chen 2E
Sat Mar 12, 2016 4:27 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: N in Nernst Equation
Replies: 1
Views: 689

Re: N in Nernst Equation

The n in the Nernst equation stands for the transfer of electrons that were used in both balanced half-reactions of the anode and cathode. For #3B of the 2011 Final, the balanced half-reaction of the anode is 4OH - + MnO 2 → MnO 4 2- + 2H 2 O + 2e - while the balanced half-reaction of the cathode co...
by Tiffany Chen 2E
Wed Mar 09, 2016 4:21 pm
Forum: *Alcohols
Topic: priority for naming
Replies: 1
Views: 375

Re: priority for naming

Ethers and halogens are not given priority as functional groups when numbering; however, alcohols still do have priority.
by Tiffany Chen 2E
Sun Mar 06, 2016 10:19 pm
Forum: *Cycloalkenes
Topic: Cycloalkenes as Substituents
Replies: 1
Views: 280

Cycloalkenes as Substituents

If a cycloalkene was a substituent off a parent chain, what would the name of the cycloalkene end in? For example, if cyclopentane becomes cyclopentyl as a substituent, would it become cyclopentenyl as a double-bonded substituent?
by Tiffany Chen 2E
Sun Mar 06, 2016 2:48 pm
Forum: *Electrophilic Addition
Topic: Intermediates
Replies: 1
Views: 261

Re: Intermediates

To my understanding, the number of intermediates refers to the actual number of intermediate molecules that are produced by the end of the first transition state. The amount of valleys only indicates the period where intermediates have been created.
by Tiffany Chen 2E
Sun Feb 28, 2016 8:58 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Geometric Isomers
Replies: 1
Views: 319

Geometric Isomers

On page 17 of the Intro to Organic Chemistry textbook, how do you distinguish between the (E)-3,7-Dimethylocta-1,3,7-triene and (Z)-3,7-Dimethylocta-1,3,7-triene isomers? I'm thinking you start comparing at the 3 C double bond but don't know what to do beyond that? Thanks!
by Tiffany Chen 2E
Thu Feb 25, 2016 11:05 am
Forum: *Alkanes
Topic: Structures and Substituents
Replies: 2
Views: 287

Re: Structures and Substituents

Which carbon the substituent is coming off of is denoted by the number in front of the substituent in the IUPAC name. Which direction you start counting from to place the substituent doesn't matter so much when you are drawing the structure given the IUPAC name.
by Tiffany Chen 2E
Wed Feb 17, 2016 10:18 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Pseudo rate laws
Replies: 3
Views: 401

Re: Pseudo rate laws

Could someone also clarify what exactly a pseudo rate law is and what it is used for? Thanks!
by Tiffany Chen 2E
Mon Feb 15, 2016 5:15 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Energetically Favorable
Replies: 1
Views: 352

Re: Energetically Favorable

Energetically favorable reactions tend to have a negative ΔG because they decrease free energy. Being energetically favorable means the reaction releases energy and produces heat.
by Tiffany Chen 2E
Thu Feb 04, 2016 1:13 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Redox reactions
Replies: 2
Views: 338

Re: Redox reactions

Generally, a negative E° means the reaction is unfavorable. This is because in the equation ∆G°(redox)= -nFE°, a negative E° would yield a positive ∆G°. When ∆G° is positive, that means the reaction is not spontaneous and thereby unfavorable.
by Tiffany Chen 2E
Mon Feb 01, 2016 11:42 pm
Forum: Balancing Redox Reactions
Topic: Reducing and oxidizing agents
Replies: 1
Views: 267

Re: Reducing and oxidizing agents

Generally, atoms, ions, and molecules that have electron affinity tend to make strong oxidizing agents, such as non-metals. For example, F 2 is the strongest common oxidizing agent. Metals, on the other hand, lose electrons readily and are good reducing agents. In addition, the strengths of oxidizin...
by Tiffany Chen 2E
Sat Jan 23, 2016 5:26 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework problem 8.59
Replies: 5
Views: 802

Re: Homework problem 8.59

The Nitrogen is disregarded because N2 is an example of a gas in its standard state, which means that its standard enthalpy of formation is 0. Other gases in standard state and with a ΔHf of 0 include O2, F2, Br2, H2, and Cl2.
by Tiffany Chen 2E
Mon Jan 18, 2016 3:55 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: molar heat capacity
Replies: 2
Views: 323

Re: molar heat capacity

Molecules with hydrogen bonding usually have higher molar heat capacities. Substances with strong hydrogen bonds, such as water or ammonia, take the absorbed thermal energy and store it as potential energy within the hydrogen bonds. Thus, it takes more energy to increase the kinetic energy (or incre...
by Tiffany Chen 2E
Sat Jan 09, 2016 1:20 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Enthalpy and internal energy
Replies: 1
Views: 268

Re: Enthalpy and internal energy

Enthalpy is the amount of heat released or absorbed in a thermodynamic system, or in other words, a change in energy in the form of heat. Internal energy, however, is the total amount of energy stored within a system, which involves both heat transferred to and work done by the system.
by Tiffany Chen 2E
Wed Dec 02, 2015 11:34 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Determining pH of aqueous KBr
Replies: 2
Views: 3176

Re: Determining pH of aqueous KBr

If you look at KBr, it gives off neither H+ ions nor OH- ions, because K+ does not act as an acid and Br- is a neutral conjugate base, causing KBr overall to be neutral.
by Tiffany Chen 2E
Mon Nov 23, 2015 10:38 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Disregarding the X?
Replies: 1
Views: 233

Re: Disregarding the X?

You can disregard x when K<10^-4.
by Tiffany Chen 2E
Wed Nov 18, 2015 8:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to find if you -x or +x for ICE
Replies: 1
Views: 247

Re: How to find if you -x or +x for ICE

One way would be if you are given the K value. If K is a large value or K>1 you can assume that the reaction favors the products since the products constitute the numerator in the K expression (a larger numerator compared to the denominator would mean a larger K value), and thus the reactants would ...
by Tiffany Chen 2E
Tue Nov 17, 2015 11:23 pm
Forum: Ideal Gases
Topic: Effects on Equilibrium constants
Replies: 2
Views: 344

Re: Effects on Equilibrium constants

An increase in temperature will cause an endothermic reaction to shift right and favor the product. This would create more product to make for a greater numerator in the equilibrium constant, thus, increasing the equilibrium constant. Likewise, in a forward exothermic reaction, increasing the temper...
by Tiffany Chen 2E
Fri Nov 13, 2015 2:41 pm
Forum: Naming
Topic: Ligand Definition
Replies: 1
Views: 166

Re: Ligand Definition

Yes, ligands are only applicable to transition metals. A bond between a nonmetal and a metal is an ionic bond, while a bond between nonmetals is covalent.
by Tiffany Chen 2E
Mon Nov 09, 2015 12:38 am
Forum: Naming
Topic: Ligands and Transition Metal Bonding
Replies: 2
Views: 390

Re: Ligands and Transition Metal Bonding

Are there any distinguishing characteristics of coordinate covalent bonds, aside from being a bond between a transition metal and ligand? For example, are they stronger or more stable than other types of bonds?
by Tiffany Chen 2E
Fri Oct 30, 2015 3:59 pm
Forum: Dipole Moments
Topic: polarity question
Replies: 1
Views: 325

Re: polarity question

If there is only one lone pair, the molecule should be polar. The lone pair creates asymmetry within the molecule's shape because it is more localized than bonding electrons, creating an uneven distribution of electrons and subsequently changing the overall molecular dipole moment.
by Tiffany Chen 2E
Thu Oct 22, 2015 3:24 pm
Forum: Lewis Structures
Topic: Bonds
Replies: 1
Views: 257

Re: Bonds

I believe quadruple bonds are possible; however, they usually require the elements to be in the d-orbital to form, such as transition metals.
by Tiffany Chen 2E
Wed Oct 14, 2015 11:38 am
Forum: Properties of Electrons
Topic: Rydberg Formula Derivation and Units for Quiz #1
Replies: 1
Views: 422

Re: Rydberg Formula Derivation and Units for Quiz #1

I was told only to use the equation E{n}=-\frac{hR}{n^2} . However, you can use the simplified form as long as you show how you derived it from the original equation. You should use the simplified form if you are confident in your calculations, otherwise I would suggest using the original E{n}=-\fra...
by Tiffany Chen 2E
Wed Oct 14, 2015 11:22 am
Forum: SI Units, Unit Conversions
Topic: Sig figs when problem only gives you "n" values [ENDORSED]
Replies: 1
Views: 431

Re: Sig figs when problem only gives you "n" values [ENDORSED]

Yes, you should use as many sig figs as are in the constants you use.
by Tiffany Chen 2E
Fri Oct 09, 2015 3:57 pm
Forum: Significant Figures
Topic: How often to round sf in multi-step calculations
Replies: 1
Views: 479

Re: How often to round sf in multi-step calculations

Personally, for a problem like this, I would actually rearrange the equation c=λv into v=c/λ and then plug the rearranged equation into E=hv for v in order to avoid any rounding errors. However, if you were to do it with multiple steps, my TA actually told me to round the first answer at least 2 sig...
by Tiffany Chen 2E
Mon Oct 05, 2015 12:01 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Indeterminacy Equation
Replies: 1
Views: 267

Re: Heisenberg Indeterminacy Equation

Someone elaborate or correct me if I am wrong, but I believe the 4pi has to do with the ways one can express frequency. This equation specifically involves the number of cycles per second (as in Hz) but can also be considered as the number of radians covered per second so the 4pi must be involved in...

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