Search found 77 matches

by Albert Chong_1L
Sun Mar 13, 2016 12:05 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy of surroundings for irreversible expansion
Replies: 1
Views: 315

Entropy of surroundings for irreversible expansion

Why is surrounding entropy = 0 for an irreversible expansion? The question was posed before, but with no confirmed answer. Thanks.
by Albert Chong_1L
Sat Mar 12, 2016 5:43 pm
Forum: Administrative Questions and Class Announcements
Topic: Redundant Numbering
Replies: 1
Views: 216

Redundant Numbering

Hi,

Is it acceptable to use redundant numbering when naming?
For example, will propan-1-al be accepted for full credit?

Thanks.
by Albert Chong_1L
Fri Mar 11, 2016 8:05 pm
Forum: *Cycloalkenes
Topic: Winter 2012 Final Exam Q5
Replies: 3
Views: 487

Re: Winter 2012 Final Exam Q5

Chem_Mod wrote:Yeah, it has to do with the double bond.


Could you explain what the double bond means in terms of the cis/trans? Thanks.
by Albert Chong_1L
Fri Mar 11, 2016 3:19 pm
Forum: *Cycloalkenes
Topic: Winter 2012 Final Exam Q5
Replies: 3
Views: 487

Winter 2012 Final Exam Q5

Hi,

For this question, which asks for the IUPAC name for a cycloalkene with only one functional group that sticks out of the main chain, how do we decide if it is cis or trans? Does it have something to do with the double bond?

Thanks.
by Albert Chong_1L
Wed Mar 09, 2016 11:19 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Signs for Dihedral Angles
Replies: 1
Views: 240

Signs for Dihedral Angles

Hi.

Do the + and - in dihedral angles refer to the back carbon rotating or the front one?
Also, do we have to include signs for the final? or can we simply state the angle?

Thanks.
by Albert Chong_1L
Wed Mar 09, 2016 12:17 am
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Newman projections when 2 carbons are not specified.
Replies: 1
Views: 242

Newman projections when 2 carbons are not specified.

Hi,

How do we decide which carbons to draw a Newman projection for if they are not stated?

One example is Self-Test 3.3B in Intro to Organics.
Draw a Newman projection for the gauche conformation of 1-iodobutane.

Thanks.
by Albert Chong_1L
Mon Mar 07, 2016 11:33 pm
Forum: Administrative Questions and Class Announcements
Topic: Uses of Various Functional Groups and Organic Comp
Replies: 1
Views: 247

Uses of Various Functional Groups and Organic Comp

Hi,

For the final do we have to memorize the various real-world connections for various functional groups and organic compounds?
For example, that Ethanal is present in plants and their products?

Thanks.
by Albert Chong_1L
Mon Mar 07, 2016 10:16 pm
Forum: *Alkynes
Topic: Priority of Double Bonds, Triple Bonds, and other F. Groups
Replies: 1
Views: 977

Priority of Double Bonds, Triple Bonds, and other F. Groups

Hi, I was wondering the priority for double bonds, triple bonds, and other functional groups. I believe double and triple bonds take priority over all other functional groups. I also think that double bonds take priority over triple bonds. These conclusions are derived from various examples. Can som...
by Albert Chong_1L
Mon Mar 07, 2016 9:55 pm
Forum: *Alcohols
Topic: Naming priority between double bond and functional group
Replies: 4
Views: 4537

Re: Naming priority between double bond and functional group

There is an example in the book where a double bond takes precedence over a chloro (halide) substituent...
Maybe halides are are an exception? If so, I would expect ethers to be as well...
by Albert Chong_1L
Mon Mar 07, 2016 9:09 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Steric Factor
Replies: 1
Views: 501

Re: Steric Factor

Hi, The unfavorable steric factor in terms of transition states refers to how the specific orientation requirement of a TS causes its change in entropy to be negative, and thus Free Energy change to be positive. In terms of steric strain, this refers to the conformational strain produced when the el...
by Albert Chong_1L
Mon Mar 07, 2016 9:01 am
Forum: *Complex Reaction Coordinate Diagrams
Topic: Reaction Profiles
Replies: 1
Views: 459

Re: Reaction Profiles

Hi,

The products are thermodynamically stable if they have lower Free Energy than the reactants (1&2).
A reaction is kinetically stable if it has a high activation energy, because few reactants will become products at normal temperatures (2&4).
by Albert Chong_1L
Thu Mar 03, 2016 9:25 pm
Forum: *Alkanes
Topic: Substituents in Condensed Structural Formula
Replies: 1
Views: 230

Substituents in Condensed Structural Formula

Hi.

Are Substituents still placed in parentheses for Condensed Structural Formulas?

Thanks.
by Albert Chong_1L
Tue Mar 01, 2016 8:12 pm
Forum: *Alkanes
Topic: Alphabetizing Alkyls and Halogens
Replies: 1
Views: 246

Alphabetizing Alkyls and Halogens

Hi, I was wondering if you alphabetize when both alkyls and halogens are included in a structure.

That is, if both chlorine and a methyl group were attached to an alkane, would the structure be for example, 2- chloro-3-methylnonane?
by Albert Chong_1L
Tue Mar 01, 2016 8:10 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Cis/Trans
Replies: 3
Views: 410

Re: Cis/Trans

Nope. Because for triple bonds, there is only one structure possible. A linear one.
by Albert Chong_1L
Mon Feb 29, 2016 8:50 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Activation Energy
Replies: 1
Views: 224

Re: Activation Energy

The distance between the reactant potential energy and the potential energy of the transition state is the activation energy needed to cause that reaction to occur.
by Albert Chong_1L
Mon Feb 29, 2016 8:48 pm
Forum: *Alcohols
Topic: Naming priority between double bond and functional group
Replies: 4
Views: 4537

Re: Naming priority between double bond and functional group

I think we prioritize other functional groups over double bonds. Would be great if someone could confirm.
by Albert Chong_1L
Mon Feb 29, 2016 8:45 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Cis/Trans
Replies: 3
Views: 410

Re: Cis/Trans

First of all, cis and trans isomers occur only when there are double bonds in the molecule. To determine cis or trans, look individually at each carbon and what is connected to it. Decide which of the two species connected to each carbon is greater in atomic number, and if they are the same, keep mo...
by Albert Chong_1L
Sun Feb 28, 2016 2:03 pm
Forum: *Alkanes
Topic: Capitalization in (Organic) Naming
Replies: 1
Views: 209

Capitalization in (Organic) Naming

In general, does capitalization matter for organic naming?
If so, when do we capitalize?
I've seen things capitalized and not capitalized, so just want to check.

Thanks.
by Albert Chong_1L
Sat Feb 27, 2016 10:16 pm
Forum: *Alkenes
Topic: Condensed Structural Formulas for Alkenes and Alkynes
Replies: 1
Views: 1203

Condensed Structural Formulas for Alkenes and Alkynes

Hi, I was wondering for condensed structural formulas of Alkenes and Alkynes, do the double and triple bonds have to be shown? For example, would the condensed structural formula of butene be CH2=CHCH2CH3 or CH2CHCH2CH3? Also, just to confirm, the condensed structural formula and structural formula ...
by Albert Chong_1L
Wed Feb 24, 2016 10:19 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Why will this TS not have negative enthalpy?
Replies: 1
Views: 291

Why will this TS not have negative enthalpy?

Hi I was wondering why transition states always have positive enthalpy changes despite TS that involve solely bond formation. One example would be the second step of electrophilic addition of HBr to Propene in which the second step involves a Br anion attaching to a carbocation. Since the formation ...
by Albert Chong_1L
Wed Feb 24, 2016 10:16 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Why Transition States always have Positive Enthalpy
Replies: 2
Views: 363

Re: Why Transition States always have Positive Enthalpy

Yes. That's right. But what about the example I gave?
by Albert Chong_1L
Wed Feb 24, 2016 7:45 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Why Transition States always have Positive Enthalpy
Replies: 2
Views: 363

Why Transition States always have Positive Enthalpy

Hi I was wondering why transition states always have positive enthalpy changes despite TS that involve solely bond formation. One example would be the second step of electrophilic addition of HBr to Propene in which the second step involves a Br anion attaching to a carbocation. Since the formation ...
by Albert Chong_1L
Tue Feb 23, 2016 9:13 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Electrolysis
Replies: 1
Views: 212

Re: Electrolysis

An external energy source supplies electric current to an electrolytic cell. By introducing an external current, it can drive a non spontaneous reaction. In an electrolytic cell, both electrodes are submerged in the SAME solution. When the positive ions in the solution collide with the negative elec...
by Albert Chong_1L
Tue Feb 23, 2016 6:04 pm
Forum: *Alkanes
Topic: Naming Compounds Clarification
Replies: 1
Views: 288

Re: Naming Compounds Clarification

I agree with your first question that the ordering seems strange. To answer your second question, the substituent listed first is always given the lower number if equivalent numbering is possible. However, if lower numbers in general can be obtained by giving the first substituent a higher number th...
by Albert Chong_1L
Thu Feb 18, 2016 10:28 pm
Forum: General Rate Laws
Topic: Unique Rate Law
Replies: 1
Views: 297

Re: Unique Rate Law

Good question.

I think since we are told to find the initial rate of decomposition and we know that E is consumed at 5 times the unique average rate (which applies without alteration only to species with coefficient 1), we should multiply by 5.

Would double check though.
by Albert Chong_1L
Thu Feb 18, 2016 10:18 pm
Forum: General Rate Laws
Topic: General Rate Laws
Replies: 1
Views: 217

Re: General Rate Laws

I'm not 100% sure what you are asking, but the differential rate law (Rate=k[A]^n) is useful for comparison between data in experiments to determine what the orders are for each reactant.
by Albert Chong_1L
Tue Feb 16, 2016 7:14 pm
Forum: General Rate Laws
Topic: How Balancing Affects Rate Law
Replies: 1
Views: 328

How Balancing Affects Rate Law

Hi, I was wondering if equations should be balanced before rate laws are derived. That is, for Question 3 of Quiz Prep 2, the question states that rate=k[N2O]... However, when the reaction in question is balanced, N2O has a 2 coefficient. Does this not change the rate equation to become rate=k[N2O]^...
by Albert Chong_1L
Tue Feb 16, 2016 7:09 pm
Forum: General Rate Laws
Topic: Units question
Replies: 2
Views: 308

Re: Units question

If the question does not specify differently, I would use the time units that are used in the givens.
by Albert Chong_1L
Mon Feb 15, 2016 1:36 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Pseudo Rate Laws
Replies: 1
Views: 312

Re: Pseudo Rate Laws

The concentration of the reactant being tested has to be small enough relative to the concentration of the other reactants that the concentration of the other reactants will remain essentially constant as the reactant being tested is being consumed.
by Albert Chong_1L
Mon Feb 15, 2016 1:32 pm
Forum: First Order Reactions
Topic: Initial Rate
Replies: 1
Views: 238

Re: Initial Rate

You can assume first order with respect to the species in question when the reaction rate doubles due to a doubling of the concentration of that species.
by Albert Chong_1L
Tue Feb 09, 2016 11:41 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 2
Views: 324

Re: Spontaneity

deltaS represents the entropy change of the exact reaction you are looking at. deltaSo represents the entropy change of the reaction at standard conditions. While deltaS0 might be positive and thus spontaneous at normal conditions, deltaS might not be positive at certain conditions (or visa versa). ...
by Albert Chong_1L
Tue Feb 09, 2016 8:53 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: change in entropy for adiabatic systems
Replies: 4
Views: 672

Re: change in entropy for adiabatic systems

For reversible adiabatic process, delta S should be 0. I can see that is true through deltaS=q/T, since deltaS will be 0 when q is 0. However, if V2/V1 can be substituted for T2/T1 in the equation deltaS=nCln(T2/T1), then how does this equation show deltaS as 0 when q=0 (adiabatic)? Is this equatio...
by Albert Chong_1L
Mon Feb 08, 2016 6:41 pm
Forum: Calculating Work of Expansion
Topic: Ideal Gases Formula Pt. 2
Replies: 2
Views: 275

Re: Ideal Gases Formula Pt. 2

One instance would be when you find the change in entropy of a monatomic ideal gas due to change in temperature.
by Albert Chong_1L
Mon Feb 08, 2016 6:39 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: change in entropy for adiabatic systems
Replies: 4
Views: 672

Re: change in entropy for adiabatic systems

Factors other than heat flow (q) can affect entropy. For example, if volume was increased for a gas, there would be more entropy since the gas molecules have more possible micro states in which to exist.
by Albert Chong_1L
Tue Feb 02, 2016 2:00 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Notation
Replies: 1
Views: 228

Re: Cell Notation

I'm not 100% sure, but from what I have seen, the cell notation usually follows the order that the ions are consumed and produced.

If the reaction was Fe(III) + e- --> Fe(II), for example, I think it would be Fe3+, Fe2+ since Fe3+ becomes Fe2+.

Would be great if someone could verify.
by Albert Chong_1L
Mon Feb 01, 2016 6:25 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Emax/wmax
Replies: 1
Views: 371

Re: Emax/wmax

E=Electromotive force=Cell potential. Cell potential is the amount of electrical potential energy created by differences in the charge of two half cells. It is greatest when the current is near 0 and the electrons experience the strongest pull from one half cell to the other. Wmax is the maximum amo...
by Albert Chong_1L
Tue Jan 26, 2016 5:26 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Which has more entropy?
Replies: 4
Views: 1364

Which has more entropy?

Hi.

For the same mass, would fewer, larger molecules have more entropy or more, smaller molecules. Why?
by Albert Chong_1L
Tue Jan 26, 2016 12:46 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Molar Heat Capacity
Replies: 1
Views: 283

Re: Molar Heat Capacity

Diatomic or polyatomic gases have higher molar heat capacities than monoatomic gases because they have more fundamental particles that are able to absorb energy and use it to perform translational/ vibrational/ rotational motion.
by Albert Chong_1L
Sun Jan 24, 2016 2:35 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Work/ reversible expansion
Replies: 1
Views: 237

Re: Work/ reversible expansion

Isothermal means that the temperature does not change during this expansion. Reversible means that the expansion can be reversed with the slightest push from external forces. Essentially, the system goes to equilibrium with the surroundings at each infinitely small step of the expansion. The pressur...
by Albert Chong_1L
Sun Jan 24, 2016 12:17 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Coefficients for Calculating Standard Enthalpy
Replies: 1
Views: 262

Coefficients for Calculating Standard Enthalpy

Hi.

What coefficients are used when calculating standard enthalpy for a reaction?
Some sources say to make the lowest coefficient 1 in the equation, and others say to make the molecule in question have a coefficient of 1 (with other molecules having fractional coefficients)...
by Albert Chong_1L
Fri Jan 22, 2016 10:33 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calculating final temperature of a substance
Replies: 1
Views: 217

Re: Calculating final temperature of a substance

Use the temperature provided for each substance as its initial temperature.
Then use Tf in your equation to represent final temperature. Tf will be the same for both substances after the temperatures comes to equilibrium.
Finally, you can combine the two Tf's into one variable and solve.
by Albert Chong_1L
Tue Jan 19, 2016 4:56 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard entropy of vaporization of water (HW 9.19)
Replies: 2
Views: 377

Re: Standard entropy of vaporization of water (HW 9.19)

For the phase change piece, you use the entropy of vaporization of water at 100C, which is 109.0J/Kmol.
For the other pieces, yes, use dS=Cln(T2/T1).
Then, add al the pieces together to get total S change.
by Albert Chong_1L
Mon Jan 18, 2016 9:18 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Entropy
Replies: 1
Views: 261

Re: Entropy

Entropy is an extensive property because it depends on the volume of the substance in question.
When there is more volume, there is greater degeneracy since there are more microstates for the same energy state to be achieved.
Greater degeneracy equates to greater Entropy by the equation: S=kBlnW
by Albert Chong_1L
Mon Jan 11, 2016 11:18 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Purpose of Pressurized Oxygen Gas in Bomb Calorimeter
Replies: 1
Views: 358

Purpose of Pressurized Oxygen Gas in Bomb Calorimeter

Hi.

What is the purpose of the pressurized oxygen gas in bomb calorimeters?
I presume it has something to do with isolating the sample from the environment?

Thanks.
by Albert Chong_1L
Mon Jan 11, 2016 11:11 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Reg Calorimeter v. Bomb Calorimeter
Replies: 3
Views: 1018

Re: Reg Calorimeter v. Bomb Calorimeter

A bomb calorimeter provides an isolated system at constant pressure and volume.
A regular calorimeter, such a coffee cup calorimeter, allows pressure to equalize with the environment.
Essentially, a bomb calorimeter is airtight/sealed, while a regular calorimeter is open.
by Albert Chong_1L
Fri Jan 08, 2016 2:24 pm
Forum: Phase Changes & Related Calculations
Topic: Definition of a State Function
Replies: 2
Views: 275

Re: Definition of a State Function

- A state function refers to an intrinsic property of a substance/object. - Enthalpy is equal to the total heat content of a system. - The total heat content of a system is an intrinsic property. It exists even when the object/substance is not undergoing any action. - Heat on the other hand, refers ...
by Albert Chong_1L
Fri Jan 08, 2016 2:19 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat capacity of an ideal gas
Replies: 1
Views: 264

Re: Heat capacity of an ideal gas

- Heat capacity is the amount of heat needed to raise the temperature of a substance/object in question by one degree. - For any gas, an increase in temperature causes it to expand. - For a gas at constant pressure, this expansion causes it to push against the atmospheric pressure of the surrounding...
by Albert Chong_1L
Sun Dec 06, 2015 1:32 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Acid Strength
Replies: 1
Views: 590

Re: Acid Strength

See which conjugate bases for the acids will be most stable and most able to withdraw negative charge/electrons after deprotonation.
Generally, conjugate bases with resonance and electronegative atoms will be correspondent to stronger acids
by Albert Chong_1L
Sun Dec 06, 2015 1:29 pm
Forum: Conjugate Acids & Bases
Topic: Conjugate Base Stability
Replies: 2
Views: 1544

Re: Conjugate Base Stability

It means that after the acid is deprotonated, the high amounts of negative charge are withdrawn by other atoms on the conjugate base, and the resonance helps to distribute the negative charge for more stability.
by Albert Chong_1L
Sun Dec 06, 2015 1:27 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bond Order and Bond Length
Replies: 6
Views: 1019

Re: Bond Order and Bond Length

Greater bond order = stronger bond = shorter bond
by Albert Chong_1L
Sun Dec 06, 2015 1:26 pm
Forum: *Titrations & Titration Calculations
Topic: solving quadratics
Replies: 1
Views: 278

Re: solving quadratics

If the x is less than 5% of the quantity it is subtracted by, it may be omitted because it is relatively so much smaller.
by Albert Chong_1L
Sun Dec 06, 2015 11:02 am
Forum: *Titrations & Titration Calculations
Topic: Find the final pH of the final solution in a titration
Replies: 1
Views: 441

Re: Find the final pH of the final solution in a titration

pH of a titration of strong base with a strong acid is 7.
The ions attached to the H+ and OH- do not affect pH and combine to produce a neutral salt.

As for finding volume, calculate how many moles of base need to be neutralized.
Then, calculate the volume of acid that will contain that many moles.
by Albert Chong_1L
Thu Dec 03, 2015 1:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Using Moles in Ice Table
Replies: 1
Views: 1469

Using Moles in Ice Table

Hi,

When can one use moles in the ice table?
I assume only when the volume is 1L since Kc is a set value and applies when concentrations are used?
If volume is 1L, moles would essentially be the same as concentrations?
by Albert Chong_1L
Mon Nov 30, 2015 1:22 pm
Forum: *Biological Importance of Buffer Solutions
Topic: Buffer solutions and salt
Replies: 2
Views: 691

Re: Buffer solutions and salt

A salt is used to supply the conjugate acid/base of the weak acid/base that is being used as a buffer.
If no salt is added, the buffer might not be at the optimum level since the amount of acid/base and conjugate are not going to be necessarily equal.
by Albert Chong_1L
Mon Nov 30, 2015 1:19 pm
Forum: Identifying Acidic & Basic Salts
Topic: Soluble salts
Replies: 1
Views: 317

Re: Soluble salts

By definition, a salt is an ionic compound. Thus, its component atoms/molecules are necessarily charged (either positive of negative). When these charged components interact with a polar medium such as water, the ionic components are pulled away from each other. A salt dissolves when the positive en...
by Albert Chong_1L
Mon Nov 30, 2015 11:23 am
Forum: Conjugate Acids & Bases
Topic: Acidic or Basic Buffer?
Replies: 1
Views: 355

Acidic or Basic Buffer?

Hi, Since weak acids and weak bases both function as buffers and can act as a sink or source of protons, does that mean that to buffer a solution, it does't matter whether a weak acid or weak base is used as long as the PKa is close to the desired pH? That is, a weak acid can buffer an acidic soluti...
by Albert Chong_1L
Fri Nov 27, 2015 6:45 pm
Forum: Conjugate Acids & Bases
Topic: NH4+ and NH3
Replies: 3
Views: 3500

NH4+ and NH3

Hi.

Normally the conjugate acid of a weak base is a strong acid, however, the conjugate acid of the weak base NH3 is a weak acid, NH4+.
Why is this the case?
by Albert Chong_1L
Thu Nov 26, 2015 12:41 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Dissociation of a Compound
Replies: 1
Views: 295

Re: Dissociation of a Compound

If the species is a strong acid or base, it will dissociate essentially completely in water. If it is a weak acid/base, it will only dissociate partially in water, and some will remain in weak acid/base form. To determine if an acid/base is strong, examine the Ka or Kb value. If Ka or Kb is large, t...
by Albert Chong_1L
Mon Nov 23, 2015 6:55 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Selecting the Appropriate Buffer
Replies: 1
Views: 365

Selecting the Appropriate Buffer

Hi, Since buffers can be weak acids or bases and either will neutralize both strong acids and bases, how does one select the best buffering solution? I assume that adding a salt containing the conjugate of a weak acid or base would be the easiest way to adjust buffering capacity in which case weak a...
by Albert Chong_1L
Mon Nov 23, 2015 12:37 pm
Forum: Lewis Acids & Bases
Topic: Determining Strength of an Acid/Base
Replies: 2
Views: 573

Re: Determining Strength of an Acid/Base

To determine the strength of an Acid/Base, you can calculate and interpret the Ka and Kb values. Remember that Ka = [H+][A-] / [HA] and Kb = [BH+][OH-] / [B]. Ka and Kb are the acid and base dissociation constants respectively. A higher Ka or Kb would mean a stronger acid or base respectively. In ge...
by Albert Chong_1L
Mon Nov 16, 2015 2:05 pm
Forum: Naming
Topic: Ligand order in TM compound formulas & Bracket Use
Replies: 1
Views: 292

Ligand order in TM compound formulas & Bracket Use

Hi, When we write the formula for a TM, does it matter the order which the ligands are placed in? I know for naming that the ligands come in alphabetical order before the TM. For example, for tetraamminedichloronickelate(II), would the formula be: [NiCl2(NH3)4] or [Ni(NH3)4Cl2] Also, do we put brack...
by Albert Chong_1L
Mon Nov 16, 2015 1:53 pm
Forum: Naming
Topic: naming a given complex
Replies: 1
Views: 206

Re: naming a given complex

It's alphabetical, so cyano before ethylenediamine.
by Albert Chong_1L
Mon Nov 16, 2015 1:48 pm
Forum: Naming
Topic: WorkBook Preparation for Quiz 3
Replies: 1
Views: 234

Re: WorkBook Preparation for Quiz 3

Let's clarify first that both the CN- (cyano) and Cl- (chloro) are (anionic) ligands.
From there, we just put them in alphabetical order so chloro is before cyano.
by Albert Chong_1L
Mon Nov 16, 2015 1:36 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changes in both reactants and products
Replies: 1
Views: 296

Re: Changes in both reactants and products

If concentration of both reactants and products change, you would use the new concentrations as the initials in your ice table and calculate a Q value. Then you would compare the derived Q with the known K value during equilibrium. If Q is smaller than K, the reaction will proceed towards the produc...
by Albert Chong_1L
Mon Nov 09, 2015 1:07 pm
Forum: Ideal Gases
Topic: Effect of inert gasses on equilibrium
Replies: 1
Views: 344

Effect of inert gasses on equilibrium

Hi, I know that adding any quantity of inert gas to an equilibrium reaction has no effect on the equilibrium constant and reactant/product concentrations remain the same. However, I don't see why adding an inert gas does not shift the equilibrium towards the side with fewer moles of gas since the in...
by Albert Chong_1L
Mon Nov 02, 2015 8:33 pm
Forum: Sigma & Pi Bonds
Topic: Electron Configuration Involving Sigma and Pi bonds
Replies: 5
Views: 29824

Re: Electron Configuration Involving Sigma and Pi bonds

Yes, Lisa. The subscript numbers represent which energy level the (valence) electron(s) are in.
So if an electron was on Pi2px, for example, it would be in the 2nd energy level.
by Albert Chong_1L
Mon Nov 02, 2015 1:13 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Responding to Molecular Orbital Questions on the Midterm
Replies: 1
Views: 282

Responding to Molecular Orbital Questions on the Midterm

Hi, If asked to identify the molecular orbital that an unpaired electron occupies in a molecule, are we expected to provide all three of these or only 1 or 2 of them? (If all 3, an example answer would be Pi*2Py) 1. The energy level of the orbital 2. Whether it is bonding or antibonding 3. Shape of ...
by Albert Chong_1L
Fri Oct 30, 2015 10:20 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Fractional Bond Orders Greater than 1
Replies: 1
Views: 290

Fractional Bond Orders Greater than 1

Hi,

I was wondering if a molecule with a fractional bond order of 2.5 is more stable than a molecule with a integer bond number of 2. (It should be since 2.5 is greater than 2?)

Thanks.
by Albert Chong_1L
Mon Oct 26, 2015 2:11 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Energy Levels for Antibonding Molecular Orbitals
Replies: 1
Views: 210

Energy Levels for Antibonding Molecular Orbitals

Hi,

For antibonding molecular orbitals, I was wondering why the sigma*s orbitals have a higher energy than the pi*p orbitals. In bonding orbitals, the opposite is true because s orbital electrons penetrate less than p orbital electrons.

Thanks.
by Albert Chong_1L
Mon Oct 19, 2015 5:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: The Square Planar Shape
Replies: 1
Views: 303

The Square Planar Shape

Hi all,

I was wondering why a molecule with Square Planar Configuration (AX4E2) would prefer staying in a 2D plane rather than using 3D space to minimize electron repulsion. Perhaps the 2D shape just happens to be the one that minimizes repulsions?

Thanks.
by Albert Chong_1L
Mon Oct 12, 2015 1:02 pm
Forum: Octet Exceptions
Topic: Affect of Radicals on DNA
Replies: 1
Views: 321

Affect of Radicals on DNA

In what way do radicals react/interact with DNA to damage it?
by Albert Chong_1L
Mon Oct 12, 2015 12:58 pm
Forum: Lewis Structures
Topic: Electron Orbitals in Lewis Structures
Replies: 1
Views: 224

Electron Orbitals in Lewis Structures

How does one correlate the electrons of a Lewis structure to which orbitals they are in? For example, for oxygen, is one electron pair assumed to belong to the s orbital while the other pair and unpaired electrons are assumed to belong to the p orbitals?
by Albert Chong_1L
Wed Oct 07, 2015 7:57 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Energy Levels of d and s
Replies: 3
Views: 458

Re: Energy Levels of d and s

First recall that subshells with higher “l” (the quantum number “l”) values have greater energy than subshells with lower “l” values. For example, the f orbital (l=3) has more energy than the d orbital (l=2). Electrons of higher orbitals are “less penetrating” (less likely to be found near the nucle...
by Albert Chong_1L
Fri Oct 02, 2015 11:20 am
Forum: Properties of Light
Topic: Momentum of Photons
Replies: 1
Views: 270

Momentum of Photons

How does a photon have momentum p (as in E=pc) if it has no rest mass?
Wouldn't momentum, p=mv=0?
Does that mean that photons have mass but the mass is so tiny it can be considered 0?
by Albert Chong_1L
Wed Sep 30, 2015 12:51 am
Forum: SI Units, Unit Conversions
Topic: Units for Plank's Constant [ENDORSED]
Replies: 3
Views: 599

Units for Plank's Constant [ENDORSED]

Plank's constant sometimes uses the units "J-s" and other times "m^2 kg / s."
How does one become the other and which should we use for class?

Thanks!
by Albert Chong_1L
Wed Sep 30, 2015 12:28 am
Forum: Balancing Redox Reactions
Topic: Identifying a Redox Reaction
Replies: 1
Views: 3233

Identifying a Redox Reaction

How does one quickly identify a reaction as redox?
Are there any giveaways to look for in the reaction?

Thanks in advance.

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