Search found 68 matches

by kshalbi
Sat Mar 12, 2016 12:02 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Ea and rate constant
Replies: 3
Views: 482

Ea and rate constant

When an enzyme lowers the Ea and causes the reaction to speed up, is it also lowering k or just lowering the activation energy. Or is activation energy calculated into k?
by kshalbi
Wed Mar 09, 2016 7:16 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: 2013 final #8c
Replies: 1
Views: 255

2013 final #8c

How do you know this is chair just by looking at it?
by kshalbi
Wed Mar 09, 2016 7:02 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: 2013 Final #8
Replies: 1
Views: 292

2013 Final #8

Would the projection drawn on the right also be correct?
by kshalbi
Wed Mar 09, 2016 12:00 am
Forum: *Cyclopropanes and Cyclobutanes
Topic: most stable cyclobutane conformation
Replies: 1
Views: 913

most stable cyclobutane conformation

If asked to draw the most stable conformation of cyclobutane, do we have to draw it like the picture below or can it be drawn in newman conformation?
by kshalbi
Tue Mar 08, 2016 2:51 pm
Forum: *Ketones
Topic: #7 final 2012
Replies: 1
Views: 579

#7 final 2012

Could a chem mod verify that it's okay if we write the balanced reaction in the form CnHnOn instead of the structural form.
by kshalbi
Tue Mar 08, 2016 11:05 am
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: final 2012 #5
Replies: 2
Views: 437

final 2012 #5

This picture of a cyclohexane is given ans asked: How does the ring strain of miolecule B compare to that of cyclohexane? The answer says that cyclooctene has higher ring strain than cyclohexane. How do you know this?
by kshalbi
Tue Mar 08, 2016 12:50 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Winter 2012 final question 3
Replies: 1
Views: 269

Winter 2012 final question 3

For the cell diagram, is it acceptable if we write Cr+ instead of CrCl3 and Cu2+ instead of CuSO4?
by kshalbi
Sat Mar 05, 2016 7:56 pm
Forum: *Calculations Using ΔG° = -RT ln K
Topic: Self test 3.3a
Replies: 1
Views: 559

Self test 3.3a

In this selftest, where does the k value of 1.3806503*10^-23 come from?
by kshalbi
Thu Mar 03, 2016 10:24 am
Forum: *Ketones
Topic: Common Name
Replies: 1
Views: 614

Common Name

Is the common name of this molecule 1-bromo-7-(tert)-butyl-3-chloro-4-ethylnonane? Or is the tert part supposed to be a neo-?
by kshalbi
Sun Feb 28, 2016 8:58 pm
Forum: *Alcohols
Topic: tertiary alcohol
Replies: 2
Views: 376

tertiary alcohol

Can someone please explain why this is a tertiary alcohol.
by kshalbi
Sun Feb 28, 2016 6:08 pm
Forum: *Cycloalkenes
Topic: pg 29 numbering of cycloalkene
Replies: 1
Views: 341

pg 29 numbering of cycloalkene

Instead of numbering this molecule 1,4 wouldn't it be better to number it as 1,3 by replacing the 5 with 1, 6 with 2, and 1 with 3? Why is this not correct?
by kshalbi
Sun Feb 28, 2016 12:03 am
Forum: *Alkenes
Topic: Hmwk 1.25
Replies: 4
Views: 491

Re: Hmwk 1.25

You guys beat me to it
by kshalbi
Sun Feb 28, 2016 12:02 am
Forum: *Alkenes
Topic: Hmwk 1.25
Replies: 4
Views: 491

Re: Hmwk 1.25

Silly mistake. I figured it out.
by kshalbi
Sat Feb 27, 2016 11:57 pm
Forum: *Alkenes
Topic: Hmwk 1.25
Replies: 4
Views: 491

Hmwk 1.25

The problem asks to name the alkene. I thought that the longest C chain was of 6 Carbon atoms, but according to the answer, it's a heptene. Why is this so?
by kshalbi
Sat Feb 27, 2016 9:16 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: self test 1.6A
Replies: 1
Views: 300

self test 1.6A

I dont understand why a) is a trans isomer if the CH3 groups are on the same side of the double bond. Shouldn't it be a cis isomer?
by kshalbi
Wed Feb 24, 2016 10:36 pm
Forum: *Nucleophilic Substitution
Topic: SN2 versus nucleophilic substitution reaction
Replies: 1
Views: 354

SN2 versus nucleophilic substitution reaction

How can we differentiate between a bimolecular nucleophilic substitution reaction and a nucleophilic substitution reaction?
by kshalbi
Tue Feb 23, 2016 6:28 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Isomers on Page 156 of the OBook
Replies: 2
Views: 406

Isomers on Page 156 of the OBook

Page 156 of the organic textbook says that the carbocation has a trigonal planar geometry and so the nucleophile can approach from either side and result in two possible isomers as products. What does the text mean by "either side"? From the picture, it looks like the carbocation is just f...
by kshalbi
Sun Feb 21, 2016 8:50 pm
Forum: *Nucleophiles
Topic: -CH3 Nucleophile
Replies: 2
Views: 722

-CH3 Nucleophile

Does the "-" before the CH3 represent a negative charge on the carbon, or does it just indicate where the nucleophile attaches?
by kshalbi
Sun Feb 21, 2016 6:38 pm
Forum: *Nucleophiles
Topic: Nucleophile Example in the OTextbook
Replies: 1
Views: 351

Nucleophile Example in the OTextbook

The organic textbook says that an example of a nucleophile is Ar- (eg. -C6H5). I dont understand this notation.Is it saying that an argon with a negative charge is a nucleophile? If it is, why does it give the hhydrocarbon group as an example of it?
by kshalbi
Thu Feb 18, 2016 9:53 am
Forum: Administrative Questions and Class Announcements
Topic: Quiz 2 Topics
Replies: 4
Views: 587

Re: Quiz 2 Topics

So Arrhenius is not on the quiz?
by kshalbi
Wed Feb 17, 2016 10:34 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Winter 2015 Quiz 2 Preparation #11
Replies: 3
Views: 495

Re: Winter 2015 Quiz 2 Preparation #11

wouldn't you need the activation energy though?
by kshalbi
Wed Feb 17, 2016 5:31 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius plot
Replies: 1
Views: 356

Arrhenius plot

When is the plot of the Arrhenius equation curved?
by kshalbi
Fri Feb 12, 2016 11:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Midterm 2015 2C
Replies: 1
Views: 277

Re: Midterm 2015 2C

The problem actually asks for the enthalpy of formation for HI, not the enthalpy of fusion. As you know, enthalpies of formation are given in units kJ per mole. In 2b, 42 kJ is also given in kJ/mole, so you use that instead of 84kJ which is the reaction enthalpy for 2 moles.
by kshalbi
Thu Feb 04, 2016 5:04 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Hmwk 14.101
Replies: 2
Views: 363

Hmwk 14.101

The question says that in a neuron the [K+] of ions in the cell is 20-30 times as great as that outside. The solutions manual, when using the nernst equation, writes the ln part as ln (1/30). How would I know to write it that way as opposed to ln (30/1) ?
by kshalbi
Thu Feb 04, 2016 3:43 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: statements about E cell and E¤ cell
Replies: 1
Views: 332

statements about E cell and E¤ cell

Why doesnt E¤ cell decrease as the cell rxn progresses? Also, the solutions manual says that E¤ can be calculated from K, but E cell cannot. The equation for Ecell is Ecell=E¤cell-(RT/nF) lnQ. If E¤cell can be calculated with K and Ecell is dependant on E¤, why cant E cell be found from K? Does it h...
by kshalbi
Tue Feb 02, 2016 10:15 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox in Acids and Bases
Replies: 1
Views: 413

Balancing Redox in Acids and Bases

How would I know to balance an equation the acid way or the base way if they don't specify in the question. For example, 14.15 part C says: Cd+2Ni (OH)3---> Cd (OH)2....Do I use the method for bases because there is an OH involved?
by kshalbi
Mon Feb 01, 2016 4:30 pm
Forum: Administrative Questions and Class Announcements
Topic: Undergraduate Assistant Workshops
Replies: 3
Views: 8105

Re: Undergraduate Assistant Workshops

is #2 still happening tomorrow?
by kshalbi
Tue Jan 26, 2016 2:10 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Sig Figs Regarding Gibbs Free Energy Equation
Replies: 1
Views: 255

Sig Figs Regarding Gibbs Free Energy Equation

When using the Gibbs equation, do we use the sig figs rule for addition and subtraction or that for multiplication because the equation uses both multiplication and subtraction.
by kshalbi
Mon Jan 25, 2016 10:54 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Hmwk 9.91 gibbs in the vaporization of water
Replies: 1
Views: 233

Hmwk 9.91 gibbs in the vaporization of water

To find the Gibbs free energy for the vaporization of water at 25 degrees Celsius, why can't you subtract the Gf of the gaseous state of water and the Gf of the liquid state of water?
by kshalbi
Mon Jan 25, 2016 10:07 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Hmwk 9.83
Replies: 1
Views: 271

Re: Hmwk 9.83

Jk. Br(g) isnt the pure state. The liquid form is pure.
by kshalbi
Mon Jan 25, 2016 10:00 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Hmwk 9.83
Replies: 1
Views: 271

Hmwk 9.83

Hi. So, this question asks you to find thr standard Gibbs free energy of H2 (g) +Br2 (g)--> 2HBr (g) at 298K. Why can't you just answer it by giving the Gibbs free energy of formation for HBr (g)? Instead you have to subtract the energy of the products from that of the reactants.
by kshalbi
Sat Jan 23, 2016 6:03 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Finding molar entropy of benzene
Replies: 1
Views: 333

Finding molar entropy of benzene

Is there a way to find the molar entropy of benzene by adding the molar entropies of H2 and C?
by kshalbi
Sat Jan 23, 2016 5:02 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity and molar mass
Replies: 1
Views: 291

Heat Capacity and molar mass

Do molecules with a greater molar mass have higher heat capacities than those with less mass?
by kshalbi
Tue Jan 19, 2016 9:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Adiabatic Expansion
Replies: 4
Views: 408

Re: Adiabatic Expansion

Yeah but then to find w do you use: -PdeltaV or the -nRTln (v1/v2). These two equations are what I meant by the "reversible or irreversible" equations for work.
by kshalbi
Tue Jan 19, 2016 9:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Adiabatic Expansion
Replies: 4
Views: 408

Re: Adiabatic Expansion

Yeah but then to find w do you use: -PdeltaV or the -nRTln (v1/v2). These two equations are what I meant by the "reversible or irreversible" equations for work.
by kshalbi
Tue Jan 19, 2016 9:24 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Rate of Entropy Generation
Replies: 3
Views: 494

Rate of Entropy Generation

Can the rate of entropy generation be negative?
by kshalbi
Tue Jan 19, 2016 3:48 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Adiabatic Expansion
Replies: 4
Views: 408

Adiabatic Expansion

If a gas expands adiabatically and you have to find the work it does, do you use the equation for reversible or irreversible reactions?
by kshalbi
Tue Jan 19, 2016 3:40 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Spontaneous Rxn Involving Cl
Replies: 1
Views: 270

Spontaneous Rxn Involving Cl

How do you know that Cl2 (g)--->2Cl (g) is spontaneous only at high temperatures?
by kshalbi
Tue Jan 19, 2016 3:05 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy in Isothermal and Adiabatic Rxns
Replies: 3
Views: 297

Re: Internal Energy in Isothermal and Adiabatic Rxns

Doesn't adiabatic mean that something is thermally insulating, so if it insulates, doesn't that mean that no heat is escaping so there is no change in internal energy?
by kshalbi
Fri Jan 15, 2016 10:51 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy in Isothermal and Adiabatic Rxns
Replies: 3
Views: 297

Internal Energy in Isothermal and Adiabatic Rxns

Why is it that in an isothermal rxn delta U=0 and in an adiabatic one, delta U=w? I thought that isothermal and adiabatic were similar conditions.
by kshalbi
Wed Jan 13, 2016 11:21 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Energy in compounds
Replies: 2
Views: 402

Energy in compounds

Is it true that the more energy it takes to form a compound, the more stable it is?
by kshalbi
Tue Jan 12, 2016 4:14 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Bomb Calorimeters
Replies: 1
Views: 274

Bomb Calorimeters

Is the equation q=C*delta T only used for bomb Calorimeters?
by kshalbi
Mon Jan 11, 2016 11:19 pm
Forum: Phase Changes & Related Calculations
Topic: HW 8.17 Work done in a phase change
Replies: 4
Views: 939

Re: HW 8.17

Yeah, I still don't get it.
by kshalbi
Mon Jan 11, 2016 3:25 am
Forum: Phase Changes & Related Calculations
Topic: HW 8.17 Work done in a phase change
Replies: 4
Views: 939

HW 8.17 Work done in a phase change

For image b, how do you know that work is done on the system?
by kshalbi
Sat Jan 09, 2016 1:43 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter Properties
Replies: 2
Views: 592

Calorimeter Properties

In lecture, three properties of coffee cup calorimeters were mentioned. I wrote down insulation, but I didn't get the other two? Did someone else write them down?Thanks.
by kshalbi
Sat Dec 05, 2015 9:54 am
Forum: Identifying Acidic & Basic Salts
Topic: Properties of Strong Acids
Replies: 2
Views: 398

Properties of Strong Acids

I know that a strong acide has the property that its resulting anion must be stable, but what exactly does this mean?
by kshalbi
Fri Dec 04, 2015 9:24 pm
Forum: Polyprotic Acids & Bases
Topic: 2013 Practice Final #7A
Replies: 3
Views: 747

Re: 2013 Practice Final #7A

Nevermind, figured it out.
by kshalbi
Fri Dec 04, 2015 9:00 pm
Forum: Polyprotic Acids & Bases
Topic: 2013 Practice Final #7A
Replies: 3
Views: 747

2013 Practice Final #7A

When you take the log of [B][H3O+]/[BH+], how is it equal to log([B]/[BH+])+log[H3O+]?
by kshalbi
Thu Dec 03, 2015 2:40 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH change
Replies: 2
Views: 374

Re: pH change

Most of them are in the course reader, but they're the halogen anions, alkali metal cations, and alkali earth metal cations. It's on page 147 of the course reader.
by kshalbi
Sat Nov 28, 2015 11:06 pm
Forum: Dipole Moments
Topic: Polarity of Molecules
Replies: 2
Views: 550

Re: Polarity of Molecules

Any existence of a lone pair does cause polarity as long as there is not another lone pair to cancel out the dipole moment. The lone pairs cancel each other out if they are on the same plane and there is no bonding electrons on the same plane as the lone pairs.
by kshalbi
Sat Nov 28, 2015 11:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Fall 2015 Quiz 3 #5
Replies: 1
Views: 326

Re: Fall 2015 Quiz 3 #5

What?! That's wrong? Who said that? Was it a T.A.?
by kshalbi
Fri Nov 20, 2015 5:28 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Ignoring the change in equilibrium
Replies: 3
Views: 515

Re: Ignoring the change in equilibrium

and for the non acid equations can you still ignore the change if K is 1 * 10^-3?
by kshalbi
Fri Nov 20, 2015 5:25 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Ignoring the change in equilibrium
Replies: 3
Views: 515

Ignoring the change in equilibrium

So for equations that don't involve acids and bases we can ignore the chage if it's less than 10^-3 but for ones with acids and bases it's if it's 10^-4?
by kshalbi
Fri Nov 13, 2015 2:17 pm
Forum: Naming
Topic: Pentaaminechloronickel (lll) chloride.
Replies: 1
Views: 240

Pentaaminechloronickel (lll) chloride.

Quiz three prep gives the chemical formula to this compound as [Ni (NH3)5Cl] Cl2 but I thought that the elements had to be ordered alphabetically by their symbol. Cl is after the NH3 but shouldn't it be written before if this alphabetical rule applies?
by kshalbi
Wed Nov 11, 2015 2:40 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Compression and photosynthesis. 11.115 hmwk
Replies: 4
Views: 596

Compression and photosynthesis. 11.115 hmwk

6CO2 + 6H2O-----> C6H12O6 + 6O2. I don't understand why compressing the system has, according to the book, little to no effect on the shift towards reactants or products. I thought that since pressure was being increased, the products are favored because there are fewer molecules on the product side.
by kshalbi
Sun Nov 08, 2015 8:46 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: (CO3)^2-
Replies: 1
Views: 459

(CO3)^2-

Can someone please explain to me why (CO3)^2- can be either mono or bidentate. Why can't it be polydentate?
by kshalbi
Fri Nov 06, 2015 11:46 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem 14B TA's
Replies: 1
Views: 637

Re: Chem 14B TA's

Nevermind. I figured out that they're not.
by kshalbi
Fri Nov 06, 2015 11:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW 11.11
Replies: 1
Views: 279

Re: HW 11.11

The amount of O2 is greater in the second container because you are starting with .5 moles of pure ozone which is more than .1 moles of it. Equilibrium reactions try to get rid of the change and in this case, to get rid of all the moles of O3, equilibrium will favor the forward reaction and produce ...
by kshalbi
Fri Nov 06, 2015 10:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem 14B TA's
Replies: 1
Views: 637

Chem 14B TA's

Hi. Does anyone know if the T.A.s for Chem 14 A will be the same ones for Chem 14 B? Thank you.
by kshalbi
Sat Oct 31, 2015 6:30 pm
Forum: General Science Questions
Topic: General Question about MO Diagrams
Replies: 2
Views: 1038

General Question about MO Diagrams

If on the midterm there is a question that requires us to draw MO Diagrams for four different molecules, do we have to draw all four diagrams, or can we just use the same one and erase the arrows on it?
Thank you
by kshalbi
Fri Oct 30, 2015 9:23 pm
Forum: Ionic & Covalent Bonds
Topic: Which is more ionic?
Replies: 1
Views: 334

Which is more ionic?

There's a question that says: Which is more ionic? LiH or HCl. I thought it was HCl because according to the trends in the periodic table, H and Cl should have a larger difference in electronegativity than Li and H making it more ionic, but apparently this isn't right because the answer is LiH. Can ...
by kshalbi
Thu Oct 29, 2015 7:38 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: diamagnetism and paramagnetism
Replies: 1
Views: 279

Re: diamagnetism and paramagnetism

It is not possible to figure out if something is para or dia magnetic without drawing the MO energy diagram because from everything we've learned, this diagram is the only thing we can use to see if there are unpaired electrons in an orbital of a molecule.
by kshalbi
Sat Oct 24, 2015 9:38 pm
Forum: Lewis Structures
Topic: TeCl4 Lewis Structure
Replies: 1
Views: 990

TeCl4 Lewis Structure

When drawing the Lewis Structure for this molecule, and for drawings on future quizzes and exams, it is ok if we draw the Cl atoms equally spaced around the Te atom and add the two lone electrons next to the Te atom, or do we have to represent the electron repulsion from the lone pairs by drawing th...
by kshalbi
Sat Oct 17, 2015 1:46 am
Forum: Lewis Structures
Topic: Tips on drawing out Lewis Structures?
Replies: 1
Views: 1361

Re: Tips on drawing out Lewis Structures?

Hi Joana! When drawing out Lewis Structures, you want to follow these steps: 1. The most electronegative atom goes in the middle (there are a few exceptions). Electronegativity increases when going across a period and up a group. 2. Figure out how many valence electrons each atom has and add these v...
by kshalbi
Thu Oct 08, 2015 5:35 pm
Forum: Trends in The Periodic Table
Topic: Effective Nuclear Charge
Replies: 1
Views: 347

Re: Effective Nuclear Charge

Zeff, effective nuclear charge, is the positive charge experienced by an electron. Z, is the charge of the nucleus, which is positive. Imagine a valence electron in the outermost orbital. It is repelled from the nucleus by all the negatively charged electrons that surround the nucleus. Thus, these e...
by kshalbi
Tue Sep 29, 2015 3:20 pm
Forum: Empirical & Molecular Formulas
Topic: Molecular Formulas
Replies: 3
Views: 751

Molecular Formulas

Some problems, when asking you to find the molecular formula, tell you that the substance is composed of 14% C and certain percentages of other elements. Then you proceed by treating the 14% as 14 grams. My question is that if the problem says that a substance is made of 15 g of C, 2 g of H, and 3 g...

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