## Search found 100 matches

Sun Mar 13, 2016 12:56 pm
Forum: *Cycloalkanes
Topic: Ring Strain
Replies: 1
Views: 306

### Ring Strain

Why does cyclooctene have more ring strain than cyclohexane? Does it have something to do with the double bond?
Sun Mar 13, 2016 10:05 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Maximum work
Replies: 2
Views: 685

### Re: Maximum work

Delta G= Delta H - TDeltaS
Not sure, but this is how I thought of it. Delta H is only valid under constant pressure (heat under constant pressure), and temperature in the equation isn't changing (it's not delta T). It's constant.
Sun Mar 13, 2016 10:03 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: standard molar entropies
Replies: 1
Views: 550

### Re: standard molar entropies

It's usually just the diatomic molecules H2, N2, F2, O2, I2, Cl2, Br2 in their natural phase (room temp). I think it's gaseous for all and liquid for bromine.
Sun Mar 13, 2016 9:39 am
Forum: Phase Changes & Related Calculations
Topic: Winter 2011 Final question 1A
Replies: 3
Views: 537

### Re: Winter 2011 Final question 1A

1 gram is about 1 mL
Sun Mar 13, 2016 9:36 am
Forum: Phase Changes & Related Calculations
Topic: Winter 2012 Final Question 1B
Replies: 1
Views: 298

### Re: Winter 2012 Final Question 1B

They divide by 4 moles first to get it to be per mole. Then after it's per mole, they multiply by 2 to get it per the reaction.
Sun Mar 13, 2016 9:35 am
Forum: *Alkanes
Topic: Isomers
Replies: 1
Views: 306

### Re: Isomers

Constitutional isomers usually just refers to reordering an alkane single bonded chain. Geometric usually has to do with the double bonds or rings.
Sun Mar 13, 2016 1:06 am
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Most Stable Conformation
Replies: 1
Views: 313

### Re: Most Stable Conformation

I don't know the exact details, but equatorial substituents are always the most stable, and if you have two substituents on the same carbon, then the most stable conformation will be the one where the heaver substituent is equatorial.
Sun Mar 13, 2016 12:07 am
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Cis and Trans Stability for Chairs
Replies: 1
Views: 296

### Cis and Trans Stability for Chairs

How could you tell which chair is more stable given that they both have two substituents in the equatorial position, one being cis and the other being trans? I don't have a specific molecule, but would it depend on where the substituents are located (possibly further away being more stable)? Also, I...
Sat Mar 12, 2016 11:56 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Winter 2011 Final
Replies: 1
Views: 297

### Re: Winter 2011 Final

Well the change in gas actually negative 2. That's because there's 3 moles of gas on the left side and 1 mole of gas on the right side. Also if you're confused, water is a liquid in this reaction and not a gas because it says the temperature is constant at 25 degrees celsius.
Sat Mar 12, 2016 11:51 pm
Forum: *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
Topic: Tert
Replies: 3
Views: 779

### Re: Tert

Tert is a substituent that happens to look like a capital T.
Sat Mar 12, 2016 11:27 pm
Forum: *Electrophiles
Topic: Identifying Electrophiles/Nucleophiles
Replies: 1
Views: 338

### Re: Identifying Electrophiles/Nucleophiles

Try looking at the electronegativity of the atoms in comparison to the central atom. If the central atom is delta negative then it will probably be a nucleophile and an electrophile is delta positive.
Sat Mar 12, 2016 11:11 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy of Isothermal Processes
Replies: 2
Views: 701

### Re: Internal Energy of Isothermal Processes

I think the heat cancels the work. I think of it as temperature being the only thing that can change internal energy, and there's no change in temperature in an isothermal process.
Sat Mar 12, 2016 11:01 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: E vs Z Chair
Replies: 2
Views: 387

### E vs Z Chair

How could you tell which chair is more stable given that they both have two substituents in the equatorial position, one being cis and the other being trans? I don't have a specific molecule, but would it depend on where the substituents are located (possibly further away being more stable)?
Sat Mar 12, 2016 10:51 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Quiz 3 Question1
Replies: 1
Views: 392

### Re: Quiz 3 Question1

Only a catalyst can change the activation energy. The change in k could have resulted from a temperature change. However, when Ea changes, k does change but not the other way around.
Sat Mar 12, 2016 10:48 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 2012 practice final#2A
Replies: 3
Views: 496

### Re: 2012 practice final#2A

Using the equation with volume change already accounts for the pressure change because of PV=nRT. Therefore you can use one or the other when finding the entropy. Only when there's a temperature change with a volume/pressure change do you need 2 equations with a combined entropy.
Sat Mar 12, 2016 10:38 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Irreversible Isothermal
Replies: 1
Views: 322

### Irreversible Isothermal

For an irreversible isotherm process, would the work just be -PdeltaV?
Sat Mar 12, 2016 10:24 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: E/Z
Replies: 1
Views: 296

### E/Z

Where does E/Z exist besides for double bonds? Would it be on all rings with substituents or only cyclohexane (ring or chair conformation?). If a cyclohexane had 3 substituents for example 1,3,5-trimethylcyclohexane, then what do you do for E/Z?
Sat Mar 12, 2016 9:17 pm
Forum: *Electrophiles
Topic: CO2
Replies: 1
Views: 323

### Re: CO2

The oxygens bonded to the carbon are more electronegative making C slightly positive. Therefore, it wants electrons.
Sat Mar 12, 2016 1:56 am
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Identifying Cis/Trans
Replies: 1
Views: 277

### Identifying Cis/Trans

Is cis and trans only found on double bonds and cycloalkanes with substituents (or is it only cyclohexane)? Also, how would you designate cis and trans for 3 substituents (if you can)?
Fri Mar 11, 2016 8:47 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Cis and Trans and Stability
Replies: 1
Views: 796

### Cis and Trans and Stability

Can cis and trans for a chair conformation only exist for 2 and only 2 substituents (what if there's 3 or 4)? Also, does the stability of a cis or trans chair change depending on how close or far they are to each other (all in equatorial position)? Are substituents that are furthest apart most stabl...
Wed Mar 09, 2016 9:46 pm
Forum: Calculating Work of Expansion
Topic: Final 2011 Question 1B Combustion of Methane
Replies: 1
Views: 247

### Final 2011 Question 1B Combustion of Methane

Suppose 1.00 mol of methane is combusted irreversibly at constant room temperature (25 degrees C). Calculate the work associated with this process. In the solution, it indicates the process as: CH4(g) + 2O2(g) --> 2H2O(l) + CO2(g) and that delta n(gas) = -2.00 Isn't H2O water vapor (gas) not liquid?...
Thu Mar 03, 2016 7:31 pm
Topic: Electrophilic Addition HBr with Propene
Replies: 1
Views: 333

### Electrophilic Addition HBr with Propene

In the reaction, a double bond between the 1st and 2nd carbon is attacking the hydrogen. In the book, the H from HBr bonds to the first carbon in propene, and the bromide eventually bonds to the 2nd carbon prdocuging 2-Bromopropane as the final product. Could you/should you bond the bromide with the...
Thu Mar 03, 2016 12:14 am
Forum: *Organic Reaction Mechanisms in General
Topic: Reaction Profile Exergonic Explanation
Replies: 1
Views: 227

### Reaction Profile Exergonic Explanation

How do we know that the electrophiloc addition of HBr to 2-Butene is an exergonic reaction, delta G is negative, and that the reaction is favorable without knowing what the profile looks like.
Mon Feb 29, 2016 7:45 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Constitutional Isomers with Common Names
Replies: 1
Views: 321

### Constitutional Isomers with Common Names

How would you name 2,3-dimethylbutane using common names? Would there be 2 iso groups?
Sun Feb 28, 2016 11:22 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Constitutional Isomers with Common Names
Replies: 1
Views: 244

### Constitutional Isomers with Common Names

2,3-methylbutane looks like it has 2 isohexanes. Is this correct? Also, how would you name 2 iso structures at once.
Sun Feb 28, 2016 10:39 pm
Forum: *Alkanes
Topic: Common Names
Replies: 1
Views: 164

### Common Names

When using common names, should you just recognize them by structure as opposed to connectivity by formula (i.e. iso-(CH3)2CH)? For 5,
5-Isobutyl-4methylnonane, it looks like the substituent has a CH2 in there which doesn't seem iso from the formula. However, it does look like the isobutyl shape.
Fri Feb 26, 2016 10:28 pm
Forum: *Nucleophilic Substitution
Topic: SN1 and SN2
Replies: 2
Views: 799

### SN1 and SN2

Do SN2 reactions always imply 1 transition state, and do SN1 reactions always imply 2 transition states? Also, what would the transition states be for the SN1 reaction between HO- and CH3Br? I think one of the transition states is going to be CH3 with the Br broken off. What would the second transit...
Sun Feb 21, 2016 12:25 am
Forum: Second Order Reactions
Topic: difference between consumption and decomposition
Replies: 1
Views: 420

### Re: difference between consumption and decomposition

I think that decomposition is the same thing as consumption, just more specific. The orders will therefore not be different as long as you're talking about the initial rates of reactant consumption. Hope this helps.
Tue Feb 09, 2016 3:34 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Midterm 2014 Question 8
Replies: 1
Views: 332

### Midterm 2014 Question 8

F_{2}(g)+2H^{+}(aq)+2e^{-}\rightarrow 2HF(aq),E^{o}=+3.03V F_{2}(g)+2e^{-}\rightarrow 2F^{-}(aq),E^{o}=+2.87V Calculate the value of Ka for HF. Can some explain to me the idea behind Ka again as well as why they assumed that potential difference would be nega...
Tue Feb 09, 2016 9:15 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Midterm 2014 Question 8
Replies: 2
Views: 352

### Re: Midterm 2014 Question 8

Yeah sure. F_{2}(g)+2H^{+}(aq)+2e^{-}\rightarrow 2HF(aq),E^{o}=+3.03V F_{2}(g)+2e^{-}\rightarrow 2F^{-}(aq),E^{o}=+2.87V Calculate the value of Ka for HF. Can some explain to me the idea behind Ka again as well as why they assumed that potential difference wou...
Tue Feb 09, 2016 2:18 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Midterm 2014 Question 8
Replies: 2
Views: 352

### Midterm 2014 Question 8

I'm confused as to why it is assumed that the potential difference of the cell is going to be negative. We are trying to find the Ka for HF. Is it because we need H and F to be products and HF to be a reactant that we flip the half reactions accordingly?
Fri Feb 05, 2016 9:32 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Finding K
Replies: 1
Views: 332

### Finding K

To find K, I used E not=RT/nF(lnK) in order to find K. However, when I used log K=n*E not/0.0592, the answer was different. Is this right? If so, which equation should be used?
Thu Jan 28, 2016 8:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpy Equation Balancing
Replies: 1
Views: 285

### Bond Enthalpy Equation Balancing

Use the bond enthalpies given in the table below to estimate the reaction enthalpy for burning 1 mol of Butane: C4H10 (g) + O2 (g) --> CO2 (g) + H20 (g) The answer was -2186kJ and I got -4372kJ from balancing the equation using whole numbers, which is double the answer. How would you know to use 13/...
Sun Jan 24, 2016 10:01 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal ???
Replies: 1
Views: 324

### Re: Isothermal ???

It might have to do with the fact that although work is being done and energy is being used, the same energy is put back into the system in order to keep the system at a constant temperature. Hope this helps.
Sun Jan 17, 2016 10:43 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: States
Replies: 3
Views: 428

### Re: Degeneracy

I could be wrong, but I think it might have something to do with the fact that gaseous molecules are much more loose than the rigid molecules in a liquid or solid.
Fri Jan 15, 2016 7:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Signs for enthalpy
Replies: 3
Views: 555

### Re: Signs for enthalpy

Enthalpy is positive when a bond is broken because an energy input is required to break the bond (i.e. heat energy is added to the system from the surrounding-endothermic). The same logic but opposite process is the reason enthalpy is negative when a bond is formed (exothermic).
Sun Jan 10, 2016 2:12 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific Heat Under Const. Press. vs. Const. Vol.
Replies: 2
Views: 442

### Re: Specific Heat Under Const. Press. vs. Const. Vol.

Does the amount of heat used to change the volume under constant pressure equal the amount of heat used to change the pressure under constant volume for liquids and solids? Is that why their heat capacity is the same under constant pressure or constant volume?
Sun Jan 10, 2016 2:05 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific Heat Under Const. Press. vs. Const. Vol.
Replies: 2
Views: 442

### Specific Heat Under Const. Press. vs. Const. Vol.

Would heat be used to raise the pressure under constant volume, like how some of it is used to raise the volume under constant pressure as opposed to the temperature?
Sun Jan 10, 2016 2:02 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Extensive and Intensive Properties
Replies: 1
Views: 281

### Re: Extensive and Intensive Properties

The specific heat capacity would not change if you had a different amount of the same substance. It'll still be the amount of heat required to raise a gram/mole of that substance by 1 degree celsius or kelvin. Only changing the substance would change the specific heat capacity. That's why specific h...
Sun Dec 06, 2015 12:14 am
Forum: *Titrations & Titration Calculations
Topic: Henderson Hassalbalch Weak Base Titrated with Strong Acid
Replies: 1
Views: 400

### Henderson Hassalbalch Weak Base Titrated with Strong Acid

Using the HH equation for a weak base titrated with a strong acid, would you just use the ratio of the concentration of base over acid still? Does anyone have an example?
Sat Dec 05, 2015 8:39 pm
Forum: *Titrations & Titration Calculations
Topic: How to use the Henderson Hassalbalch Equation
Replies: 1
Views: 675

### How to use the Henderson Hassalbalch Equation

How do you use the equation for a titration before the stoichiometric point? For example finding the pH of .100M HCOOH 25mL titrated with 5 mL of .150M NaOH. The pH turns out to be 3.38, and I tried finding the concentration using the new volumes, but it didn't turn out right.
Sat Dec 05, 2015 12:03 am
Forum: *Titrations & Titration Calculations
Topic: Titration of a weak base with a strong acid after stoich pt.
Replies: 1
Views: 352

### Titration of a weak base with a strong acid after stoich pt.

How come you only calculate the pH using only the amount of H+ that is in excess? Why would you not account for the already slightly acidic solution at the stoichiometric point?
Fri Dec 04, 2015 11:45 pm
Forum: *Titrations & Titration Calculations
Topic: Titration of a weak base with a strong acid
Replies: 1
Views: 407

### Titration of a weak base with a strong acid

After the stoichiometric point, when you are overshooting the weak base sample with acid, what reaction is taking place? Is the salt/acidic anion still being made, or is the strong acid just protonating water at this point?
Fri Dec 04, 2015 2:23 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Buffer Region on a pH Curve
Replies: 2
Views: 653

### Buffer Region on a pH Curve

If you had to make a pH curve for a titration, how would you know when the buffer region ends?
Fri Dec 04, 2015 2:22 pm
Forum: *Titrations & Titration Calculations
Topic: pH Curve at Equilibrium
Replies: 1
Views: 295

### pH Curve at Equilibrium

Where on the pH curve is the solution at equilibrium? Is it when the curve levels out? Why is the halfway point to the stoichiometric point where pH=pKa? Also, can someone explain again why when the concentrations of the weak acid and conjugate base are the same, it is an optimum buffer?
Thu Dec 03, 2015 3:45 am
Forum: Conjugate Acids & Bases
Topic: Autoprotolysis
Replies: 1
Views: 325

### Re: Autoprotolysis

Well in the case of water, the same type means the same molecule. Water reacts with water in order to form OH- and H3O+ in very small concentrations of neutral water.
Thu Dec 03, 2015 3:43 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: strength of acids/bases
Replies: 1
Views: 274

### Re: strength of acids/bases

Yeah. A high Ka or high Kb values indicates that more product (conjugate base or acid) is formed, which means closer to complete dissociation. Conversely, a low pKa and low pKb indicate the same thing.
Mon Nov 30, 2015 4:52 pm
Forum: Amphoteric Compounds
Topic: Amphoteric Oxide Aluminum Oxide
Replies: 1
Views: 539

### Amphoteric Oxide Aluminum Oxide

Can someone explain to me how the reaction between sodium hydroxide, sodium hydroxide, and water works? I know that aluminum oxide is acting as an acidic oxide here. It's reacting with a base, so shouldn't salt and a water form? Does this have anything to do with the water being involved as a reacta...
Mon Nov 30, 2015 2:32 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Problem 12.53 Acetic Acid vs. Formic Acid
Replies: 1
Views: 747

### Problem 12.53 Acetic Acid vs. Formic Acid

Can anyone explain why formic acid is stronger than acetic acid? I don't fully understand what the solution means when it states that the CH3 group in acetic acid has electron-donating properties.
Sun Nov 29, 2015 3:24 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: pKa2 values vs. pKa1 values
Replies: 1
Views: 947

### pKa2 values vs. pKa1 values

Can anyone explain why using exponentiation on a pKa2 value for an ion will still give you its Ka value?
Fri Nov 27, 2015 2:20 pm
Forum: Amphoteric Compounds
Topic: Amphoteric Oxide Aluminum Oxide
Replies: 3
Views: 943

### Re: Amphoteric Oxide Aluminum Oxide

I actually wrote the equation down wrong. It's $2NaOH(aq) + Al_{2}O_{3}(s)+3H_{2}O(l)\rightarrow 2Na[Al(OH)_{4}](aq)$, which is balanced, but I'm not sure if the transition metal complex is a salt or not.
Thu Nov 26, 2015 12:18 pm
Forum: Lewis Acids & Bases
Topic: Basic Oxide Reaction with an Acid
Replies: 1
Views: 338

### Basic Oxide Reaction with an Acid

For the reaction $MgO(s) + 2HCl(aq)\rightarrow MgCl_{2}(aq) + H_{2}O(l)$, the base $O^{2-}$ accepts two protons from the hydronium ions present in the hydrochloric acid solution. Is it assumed that all acidic solutions have $H_{3}O^{+}$ ions that can be used?
Thu Nov 26, 2015 12:10 pm
Forum: Amphoteric Compounds
Topic: Amphoteric Oxide Aluminum Oxide
Replies: 3
Views: 943

### Amphoteric Oxide Aluminum Oxide

Can someone explain to me how the reaction between sodium hydroxide, sodium hydroxide, and water works? 2 NaOH(aq)+Al_{2}O_{3}(s)\rightarrow 2Na[Al(OH)_{4}](aq) I know that aluminum oxide is acting as an acidic oxide here. It's reacting with a base, so shouldn't salt ...
Sun Nov 22, 2015 6:21 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Losing H
Replies: 1
Views: 318

### Re: Losing H

It's kind of like how the way ionization energy works. IE gets much higher after removing the first electron. The negatively charged ion is most stable being neutral, taking an H+ would just make it even more negative. Hope this helps.
Sun Nov 22, 2015 4:29 pm
Forum: Conjugate Acids & Bases
Topic: Relative base strength.
Replies: 1
Views: 376

### Re: Relative base strength.

Not really sure, but I'm just going to take a guess. Is BrO- the stronger base? Less oxygens means less electronegativity to pull protons. Therefore, BrO- is a weaker acid, and weaker acids are stronger bases? Does this sound right? Hope it helps you out.
Sun Nov 22, 2015 3:20 pm
Forum: Amphoteric Compounds
Topic: Determining if oxides are acidic, basic, or amphoteric
Replies: 2
Views: 2297

### Re: Determining if oxides are acidic, basic, or amphoteric

Nonmetal oxides are acidic, metal oxides are basic, and I'm not 100% sure, but I think that metalloid oxides (or metal oxides close to the metalloid line) are amphoteric. However, the reactions for amphoteric oxides could be written out in order to determine its character.
Mon Nov 16, 2015 2:52 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating Ligands
Replies: 1
Views: 293

### Chelating Ligands

Is carbonato a chelating ligand if it is bidentate? If so, can someone explain why? Carbonato can either be mono or bidentate. Is it not listed in the book as bidentate because it is more unstable/strained in this position?
Sun Nov 15, 2015 12:51 pm
Forum: Naming
Topic: Naming Using New IUPAC Convention
Replies: 1
Views: 294

### Naming Using New IUPAC Convention

Does it matter if we use the old or new convention for naming anionic ligands? If it doesn't matter, is one preferred over the other on quizzes/tests?
Sat Nov 14, 2015 4:40 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate Ligands/Problem 17.33
Replies: 1
Views: 267

### Polydentate Ligands/Problem 17.33

Does the number of atoms with lone pairs determine the maximum number of attachment sites on the ligand? I'm confused about carbonate. The solutions manual says it can either be mono or bidentate, but it has 3 oxygens with lone pairs. Does resonance affect this at all?
Sat Nov 14, 2015 4:13 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating Ligands
Replies: 3
Views: 516

### Chelating Ligands

Chelating ligands have to be polydentate I think, but how can you tell if the polydentate ligand is chelating by just using the formula?
Sat Nov 14, 2015 3:35 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Square-Planar/Tetrahedral Complex
Replies: 1
Views: 407

### Square-Planar/Tetrahedral Complex

Does anyone know why a complex with a coordination number of 4 would take on a square-planar shape over a tetrahedral shape or vice versa?
Sat Nov 14, 2015 3:01 pm
Forum: Naming
Topic: Formalities in Naming Ligands CN-
Replies: 1
Views: 261

### Formalities in Naming Ligands CN-

Is cyanido interchangeable with cyano when naming the ligand CN- in coordination compounds or complexes?
Sat Nov 14, 2015 10:10 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining Shape
Replies: 1
Views: 259

### Determining Shape

I know that most coordination compounds are either square planar, tetrahedral, or octahedral. I don't think we went too much over why since that goes into crystal field theory. The ligand (en)_{3} is polydentate, and I think it forms an octahedral coordination complex. Can anyone explain the...
Thu Nov 12, 2015 5:17 pm
Forum: Naming
Topic: Oxidation States of Trans. Metals in Coordination Compound
Replies: 1
Views: 245

### Oxidation States of Trans. Metals in Coordination Compound

Can anyone explain to me why the oxidation of cobalt in [CoBr(NH3)5]SO4 is 2? I thought it would have to be 3 for the compound to be neutral since Br has a 1-charge and sulfate has a 2- charge.
Wed Nov 11, 2015 12:50 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate Using Lewis Structures
Replies: 1
Views: 380

### Polydentate Using Lewis Structures

Are Lewis structures necessary in determining whether or not a ligand is polydentate? Also, what is the reasoning behind the idea of lone pairs and shape when it comes to whether a ligand is bidentate, tridentate, etc?
Mon Nov 09, 2015 4:03 pm
Forum: Lewis Structures
Topic: Quiz Questions
Replies: 1
Views: 443

### Re: Quiz Questions

I think that's okay. The formal charge doesn't really change the shape of a molecule. Only regions of electron density will contribute to the overall shape. Also I think you mean a charge of 0 not +0. Hope this helps you out.
Sat Oct 31, 2015 11:38 am
Forum: Dipole Moments
Topic: Dipole Moments and Polarity
Replies: 2
Views: 705

### Re: Dipole Moments and Polarity

Dipole moments are just vectors that point towards the more electronegative atom. It would help a lot if you knew the shape of the molecule as well. For example, if you wrote H2O as a linear lewis structure, then the vectors would pull with equal and opposite magnitude towards the oxygens on both si...
Sat Oct 31, 2015 11:29 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Ionization Energy
Replies: 1
Views: 372

### Re: Ionization Energy

From the MO diagram, you could just look at bond order. The higher the bond order, the more stable the molecule (meaning higher Ionization Energy). The lower the bond order, and the opposite is true. Bond order just tells you the number of bonds between the atoms basically. If there are more bonds, ...
Thu Oct 29, 2015 10:30 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape with Multiple Lone Pairs
Replies: 2
Views: 462

### Molecular Shape with Multiple Lone Pairs

Can anyone explain why the shape of a $I_{3}^{-}$ ion is linear? Does it have anything to do with the opposing repulsion of the lone pairs? I believe there are 3 on the central Iodine atom.
Sun Oct 25, 2015 2:52 pm
Forum: Electronegativity
Topic: Debye units
Replies: 1
Views: 473

### Debye units

Can anyone explain to me what the number of debyes tells you about the atoms/charges/polarity involved? I know that the electric dipole moment tells you polarity/separation of charges in Coulomb meters.
Sun Oct 25, 2015 1:12 pm
Forum: Ionic & Covalent Bonds
Topic: How do Total energy from bonds work ?
Replies: 1
Views: 331

### Re: How do Total energy from bonds work ?

Well, reactivity is typically from atoms without a full valence shell. Therefore in the case of both covalent and ionic bonding, if an octet or another desired number of E is satisfied, the atom will be less likely to react in order to achieve this completeness. For ionic bonds, I know a large amoun...
Sun Oct 25, 2015 1:03 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electronic configuration of Copper
Replies: 2
Views: 2278

### Re: Electronic configuration of Copper

Just adding on, copper is more stable with a full 3d orbital than with an incomplete 3d orbital and a full 4s orbital. This is experimentally determined data, and it has something to do with the symmetry of the electrons. Same goes for chromium, it is more stable with a half full 3d orbital (i.e. on...
Mon Oct 19, 2015 3:06 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Aufbau Principle/3d-4s Configurations
Replies: 2
Views: 1198

### Aufbau Principle/3d-4s Configurations

Can someone explain again the reasoning behind 4s being a higher energy state only when the 3d state is being or has been filled?
Mon Oct 19, 2015 12:59 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Using the Equation for Subatomic Particles
Replies: 1
Views: 455

### Using the Equation for Subatomic Particles

Logically it would make sense that the uncertainty in the position of a proton would be higher than the uncertainty in the position of an electron because protons have more mass and are confined to the nucleus; whereas, the electron has less mass and can take a position within the atomic radius. How...
Mon Oct 19, 2015 12:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations for 3.9
Replies: 3
Views: 550

### Re: Electron Configurations for 3.9

So does the 3d state a higher energy level than 4s until it is "occupied" or does the 4s state always have more energy?
Mon Oct 19, 2015 12:23 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations for 3.9
Replies: 3
Views: 550

### Electron Configurations for 3.9

Is there any particular reason why the ground state configuration of both $Co^{2+} and Fe^{2+}$ are designated at [Ar] 3d7 and [3d6] respectively? Is it appropriate to leave out the 4s orbital?
Fri Oct 16, 2015 12:50 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Ryberg equation?
Replies: 1
Views: 345

### Re: Ryberg equation?

I don't necessarily think you can't use the equation (not sure about exams), but the fundamental equation for the energy of an electron at a certain quantum number n, $E=\frac{-hR}{n^{2}}$, details the transition/direction of an electron much more.
Fri Oct 16, 2015 12:45 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Indeterminacy Equation Calculations
Replies: 1
Views: 386

### Heisenberg Indeterminacy Equation Calculations

The Indeterminacy Equation is \Delta p\Delta x\geq \frac{h}{4\pi } . Therefore, if you're given the uncertainty or indeterminacy of position, you would use the full range (+/-) since the position can take on any value within the spread right (i.e. 2x the indeterminacy of position)? Would the same id...
Sat Oct 10, 2015 9:21 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Atomic Structure
Replies: 2
Views: 351

### Re: Atomic Structure

Does it have something to do with the idea that the p state has the potential to hold more electrons than s and so on?
Sat Oct 10, 2015 5:44 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Structural Analysis
Replies: 1
Views: 224

### Structural Analysis

I'm having a bit of a hard time imagining the 3 dimensional structure of the atom and its orbitals. So here's what I know/think: The nucleus is in the center, and as n increases so does the distance from the radius. At these distances n=1, n=2, and so on, there are certain shapes/orbitals that get i...
Sat Oct 10, 2015 5:38 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Atomic Structure
Replies: 2
Views: 351

### Atomic Structure

I think that single electron systems only have degenerate energy levels for orbitals/wavefunctions with the same principal quantum number. Therefore for multi-electron systems, different subshells have different energy levels. If this comes from the quantum number l, how does angular momentum affect...
Sat Oct 10, 2015 11:44 am
Forum: Significant Figures
Topic: Sig Figs in Energy Level Questions
Replies: 1
Views: 616

### Re: Sig Figs in Energy Level Questions

If that's the only value you're given in the problem, then I'd use 1 sig fig. I don't think there should be a problem with 1 sig fig as long as you use scientific notation.
Sat Oct 10, 2015 11:42 am
Forum: Trends in The Periodic Table
Topic: Ionization Energy vs. Threshold energy
Replies: 3
Views: 1729

### Re: Ionization Energy vs. Threshold energy

I think both are the same (i.e. an electron is removed from the atom). I know ionization energy is with regards to gases, and threshold energy was associated with the photoelectric effect on a solid metal. Concepts seems pretty similar to me though.
Sat Oct 10, 2015 11:37 am
Forum: *Shrodinger Equation
Topic: Conversions between meter/nanometers/picometers
Replies: 1
Views: 1238

### Re: Conversions between meter/nanometers/picometers

It's really easy to convert from the standard meters to another prefix and vice versa when the value is not in scientific notation. You just need to look at the chart in the course reader. There are 10^{-9} meters in a nanometer. So if you have 10, 20, or 30 meters, you would just say 10*10^{9}, 20*...
Sat Oct 10, 2015 11:19 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Shielding Effect
Replies: 5
Views: 895

### Re: Shielding Effect

Shielding just means that in a multi-electron system/atom the electrons further away from the nucleus have a weaker attraction to the nucleus. The nucleus has less of a pull because other electrons closer to the nucleus repel the outer electrons (i.e. electron-electron repulsion). Valence electrons ...
Fri Oct 09, 2015 7:24 pm
Forum: *Shrodinger Equation
Topic: Wave Function
Replies: 3
Views: 620

### Re: Wave Function

By model, I mean mathematical model.
Fri Oct 09, 2015 7:24 pm
Forum: *Shrodinger Equation
Topic: Wave Function
Replies: 3
Views: 620

### Re: Wave Function

I'm not 100% sure, but I think the wave functions model the orbitals that we know about. I don't know too much about Schrodinger's Equation, but the wave functions that do model the orbitals happen to be solutions to the equation.
Fri Oct 09, 2015 7:18 pm
Forum: Properties of Electrons
Topic: Homework 1.21?
Replies: 1
Views: 1031

### Re: Homework 1.21?

You might've already figured out that the answer is the photoelectric effect. So in the experiment, a certain light (i.e. EM radiation) was used to attempt to eject an electron from a metal. If light were a wave, then simply increasing the intensity would increase the energy. However, increasing the...
Fri Oct 09, 2015 7:13 pm
Forum: Trends in The Periodic Table
Topic: Isoelectronic
Replies: 2
Views: 392

### Re: Isoelectronic

You would look at the atomic number. The higher the atomic number, the higher the nuclear charge. This means that the nucleus will pull on the electrons more, making the atom/ion smaller because of the tightness.
Fri Oct 09, 2015 7:12 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Configuration Excpetion
Replies: 2
Views: 387

### Re: Configuration Excpetion

Also, these electron configurations were experimentally determined. The explanation was that the symmetry/balance resulted in more stability, and stability should be the ground state. So technically if the electron configuration of chromium and copper didn't exist this way I suppose they wouldn't tr...
Fri Oct 09, 2015 7:09 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Configuration Excpetion
Replies: 2
Views: 387

### Re: Configuration Excpetion

It turns out that both of these atoms are more stable when the electrons "occupy" each orbital for 3d state (i.e. one electron for each of the three orbitals for chromium I think). For copper, it is more stable when the 3d state is fully occupied (i.e. two electrons for the three orbitals)...
Mon Oct 05, 2015 5:28 pm
Forum: Properties of Electrons
Topic: Ways of Doing Problem 1.15?
Replies: 2
Views: 440

### Re: Ways of Doing Problem 1.15?

Well actually, you could just solve the Fundamental Energy Difference Equation for n2. Change in E= \frac{-hR}{n^{2}}+\frac{hR}{n^{2}} . Just remember that it's Final Level- Initial Level. We know that the final level is 1 because it's in the Lyman Series for UV EM radiation. You're given the wavele...
Sat Oct 03, 2015 9:47 pm
Forum: Properties of Electrons
Topic: Atomic Spectra/Rydberg Formula for Hydrogen
Replies: 3
Views: 475

### Re: Atomic Spectra/Rydberg Formula for Hydrogen

I actually incorrectly stated "Rydberg Formula" in the place of the fundamental equation $E=\frac{-hR}{n^{2}}$. I overlooked the placement of the final and initial E levels. It makes much more sense now. Thank you for the replies.
Sat Oct 03, 2015 4:36 pm
Forum: Properties of Electrons
Topic: Question 1.15 on homework
Replies: 11
Views: 4532

### Re: Question 1.15 on homework

According to the Rydberg Formula, n1 is actually the final energy level I guess you could say. Therefore solving will only work if you designate n1 as being equal to 1. That's just the way the formula is set up. I'm pretty sure n=1 is still the final energy level though.
Sat Oct 03, 2015 3:56 pm
Forum: Properties of Electrons
Topic: Ways of Doing Problem 1.15?
Replies: 2
Views: 440

### Ways of Doing Problem 1.15?

"In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line." I know you can do this by solving for frequency (nu) and solvi...
Sat Oct 03, 2015 2:52 pm
Forum: Properties of Electrons
Topic: Question 1.15 on homework
Replies: 11
Views: 4532

### Re: Question 1.15 on homework

Spectral lines in the same series always end with the same n2 or final energy level. The Lyman series happens to contain all energy transitions that end with n=1. The initial energy level could be any energy level greater than 1 though. For the hydrogen atom, the electron that drops to n=1 will emit...
Sat Oct 03, 2015 2:20 pm
Forum: Properties of Electrons
Topic: Atomic Spectra/Rydberg Formula for Hydrogen
Replies: 3
Views: 475

### Atomic Spectra/Rydberg Formula for Hydrogen

Can someone explain why the negative sign is a part of the Rydberg Formula again. I think the formula calculates the energy of an electron at a certain level. So why does a negative change result from a lower to higher energy level? I thought that the electron absorbs energy. Conversely, why is the ...
Fri Oct 02, 2015 10:28 am
Forum: Properties of Electrons
Topic: Atomic Spectra Explanation
Replies: 1
Views: 367

### Atomic Spectra Explanation

Do the spectral lines on an emission spectrum represent all the different combinations of electrons of a certain atom moving from a higher to a lower energy level? What does the absorption spectrum show, and what do the spectral lines show on that scale. Lastly, is there any significance in the freq...
Fri Oct 02, 2015 10:25 am
Forum: Properties of Electrons
Topic: Energy Relationships in Absorption and Emission
Replies: 2
Views: 438

### Energy Relationships in Absorption and Emission

How is the energy that energizes an electron related to the photon that is emitted if it is ejected. How is the incoming energy related to the energy of an electron if it is not ejected but moves from an energy level to another?
Fri Oct 02, 2015 10:10 am
Forum: Properties of Light
Topic: Wavelike Properties of Electromagnetic Radiation/Light
Replies: 2
Views: 426

### Wavelike Properties of Electromagnetic Radiation/Light

Can anyone explain by the extent of the change in the electrical field at a given point decreases when the frequency decreases? Is the "extent of the change" referring to the slope of the display of the wave?