Search found 42 matches

by Sandeep Gurram 2E
Sat Mar 12, 2016 6:20 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Determining most stable conformation
Replies: 1
Views: 358

Determining most stable conformation

In the 2013 final question 8c, there is a Newman projection. How do you determine which conformation cyclohexane is by just looking at the newman projection?
by Sandeep Gurram 2E
Sat Mar 12, 2016 1:27 am
Forum: *Cycloalkanes
Topic: Cycloalkanes substituent?
Replies: 1
Views: 347

Re: Cycloalkanes substituent?

I would assume so. The cyclic structure is a substituent if the straight chain is longer than the cyclic structure.
by Sandeep Gurram 2E
Sat Mar 12, 2016 1:25 am
Forum: *Electrophiles
Topic: Electrophiles vs Nucleophiles
Replies: 1
Views: 374

Re: Electrophiles vs Nucleophiles

An electrophile is a species that wants to gain an electron. Usually this results in a polar bond between two elements. For example, HBr would be an electrophile as the Bromine in this compound pulls on the shared electrons, causing a positive charge around H and a negative charge around Br. A nucle...
by Sandeep Gurram 2E
Fri Mar 11, 2016 11:34 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Deciding which should be oxidizing and reducing agent
Replies: 1
Views: 350

Re: Deciding which should be oxidizing and reducing agent

Yes, the species that gets oxidized should have the lower of the two standard reduction potentials.
by Sandeep Gurram 2E
Fri Mar 11, 2016 11:28 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Priority in Methyl vs Fluorine
Replies: 1
Views: 535

Priority in Methyl vs Fluorine

Hello,

I just faced a problem where apparently a methyl group has higher priority than a fluorine; is this true? My thought process was that the fluorine should have more priority as it has a higher atomic number over carbon.

Thanks
by Sandeep Gurram 2E
Wed Mar 09, 2016 4:44 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Textbook problem - chain structure with cis and trans
Replies: 1
Views: 285

Textbook problem - chain structure with cis and trans

For the example on page 17 of the organic chemistry textbook, why is (E)-3,7-Dimethylocta-1,3,7-triene trans and not cis? Doesn't the atom group attached the double bonds indicate that this is a cis stricture?
by Sandeep Gurram 2E
Wed Feb 24, 2016 10:15 pm
Forum: *Cycloalkanes
Topic: Ring Substituents
Replies: 1
Views: 353

Ring Substituents

Is it possible for a cyclic structure to have another cyclic structure as a substituent? For example is it possible for a cyclopentane structure to have a cyclopropyl substituent?

Thanks!
by Sandeep Gurram 2E
Sun Feb 14, 2016 6:02 pm
Forum: General Rate Laws
Topic: Steady State and Pre Equilibrium Approach
Replies: 1
Views: 341

Steady State and Pre Equilibrium Approach

When do we know to use the steady state or pre equilibrium approach in determining whether a proposed elementary mechanism matches an observed rate law? Are there definitive clues to look out for?

Thank You
by Sandeep Gurram 2E
Thu Feb 04, 2016 6:14 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy of Vaporization
Replies: 1
Views: 334

Re: Enthalpy of Vaporization

This is the process where you let the water heat to the vaporizing temperature (100 C), let it vaporize at that temperature, and then let it cool back down to the initial temperature (25 C). Water cannot normally vaporize at 25C, we have to use this special process to calculate the value of it.
by Sandeep Gurram 2E
Thu Jan 28, 2016 10:48 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: internal energy state function
Replies: 1
Views: 292

Re: internal energy state function

Internal energy is a state function because it doesn't matter how one got to the final state of a certain system. A system could do 100 J of work and end up at a particular internal energy. Another system could do 100,000 J of work and arrive at the same internal energy. Regardless of how much work ...
by Sandeep Gurram 2E
Tue Jan 26, 2016 10:56 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: entropy
Replies: 1
Views: 373

Re: entropy

Entropy increases with heavier atoms as heavier atoms have more vibrational energy than lighter atoms. Additionally, entropy increases with molecular complexity. Meaning when there are more atoms attached to the central atom of a certain compound, the entropy of that particular compound increases. A...
by Sandeep Gurram 2E
Sun Jan 24, 2016 3:08 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Question 8.65
Replies: 1
Views: 353

Re: Question 8.65

The desired reaction for a standard enthalpy of formation of any compound is just a balanced chemical reaction between the constituent elements in their standard states as reactants forming the desired compound as the product. For example, in this problem the desired standard enthalpy of formation i...
by Sandeep Gurram 2E
Wed Jan 20, 2016 4:49 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Interpreting Residual Entropies
Replies: 1
Views: 417

Interpreting Residual Entropies

When you are interpreting residual entropies for of a particular compound, how do you know how many orientations it can assume? The example in the textbook showed that FClO 3 had four orientations as it was tetrahedral. Is the molecular shape the only indicator of how many orientations a compound ca...
by Sandeep Gurram 2E
Sun Jan 17, 2016 12:28 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Qsystem = -Qsurroundings help
Replies: 2
Views: 1210

Re: Qsystem = -Qsurroundings help

Inadvertently, yes. The negative sign basically shows that whatever work a system performs is absorbed by its surroundings. Contrarily, whatever work is performed on the system by the surroundings is absorbed by the system and lost by the surroundings. They are equal and opposite.

Hope that helped!
by Sandeep Gurram 2E
Sun Jan 17, 2016 12:25 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Thermodynamics: Entropy
Replies: 2
Views: 456

Re: Thermodynamics: Entropy

I think it is more along the lines of an increase in the expansion of gas will cause an increase in entropy. Entropy is a measure of disorder. Now, there is thermal disorder, disorder from increasing the thermal motion of molecules (heating a substance). There is also positional disorder, which is w...
by Sandeep Gurram 2E
Sun Jan 10, 2016 8:18 pm
Forum: Phase Changes & Related Calculations
Topic: Homework 8.27
Replies: 5
Views: 1259

Re: Homework 8.27

For problems involving irreversible expansion you would use w = -PexΔV.

For problems involving reversible, isothermal expansion, you would use w = -nRT x ln(vf/vi)

The problem usually specifies the type of expansion you're dealing with.
by Sandeep Gurram 2E
Sun Jan 10, 2016 8:13 pm
Forum: Phase Changes & Related Calculations
Topic: Heating Curve
Replies: 1
Views: 371

Re: Heating Curve

I'm assuming you're referring to 8.43, not 8.41. And you're correct in saying that the right answer is c; the solutions manual confirms this answer.
by Sandeep Gurram 2E
Sun Jan 10, 2016 8:08 pm
Forum: Phase Changes & Related Calculations
Topic: Self-Test 8.9B
Replies: 1
Views: 337

Re: Self-Test 8.9B

You wouldn't use the Hvap= H(vapor)- H(liquid) formula for this question. All you have to do is find the enthalpy of formation in terms of kJ/mol. This involves converting the amount of methanol they gave in grams to mols and then dividing the amount of heat it took to vaporize to this amount by you...
by Sandeep Gurram 2E
Sat Jan 09, 2016 5:36 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calculating heat, work, and change in internal energy
Replies: 1
Views: 373

Re: Calculating heat, work, and change in internal energy

Heat transferred under constant volume can be calculated by finding the change in internal energy, ΔU. Heat transferred under constant pressure can be calculated b finding the change in enthalpy, ΔH.
by Sandeep Gurram 2E
Sat Jan 09, 2016 5:30 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: q and Enthalpy
Replies: 1
Views: 288

Re: q and Enthalpy

I'll take a mathematical perspective to show why q = Enthalpy at constant pressure: Change in Enthalpy as a state function can be represented by the equation: ΔH = ΔU + PΔV. Where H is enthalpy, U is internal energy, P is pressure, and V is volume. To show that q = enthalpy at constant pressure we c...
by Sandeep Gurram 2E
Fri Dec 04, 2015 8:36 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty Equation
Replies: 1
Views: 305

Re: Uncertainty Equation

You would use the Heisenburg Uncertainty Equation.

ΔpΔx≥h/4π
by Sandeep Gurram 2E
Fri Dec 04, 2015 8:32 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Acid Strength
Replies: 1
Views: 784

Re: Acid Strength

Dr. Lavelle had an excellent explanation of this exact problem in his review session for the final. Basically, CH 3 is a more electron rich species than H is, and therefore has more of a negative charge associated with it. In fact H is basically considered a positive species. Because of this, CH 3 d...
by Sandeep Gurram 2E
Fri Dec 04, 2015 8:28 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Henderson-Hasselbalch
Replies: 1
Views: 342

Re: Henderson-Hasselbalch

You use the HH equation when the reaction involves a weak acid and its conjugate base. Usually this implies that the K a value is going to be smaller than 1 x 10 -4 . However if the K a value is larger than that value then it is safer to go with the ICE box. Essentially, the HH equation is an approx...
by Sandeep Gurram 2E
Fri Nov 27, 2015 8:57 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Electronegativity and acid strength
Replies: 4
Views: 3332

Re: Electronegativity and acid strength

The more electronegative a certain atom is in a molecule, the more it draws on the electron density of the overall molecule. This pulling actually results in a higher stabilization state for the molecule. Therefore, the more electronegative a particular element is, the harder it pulls, and the more ...
by Sandeep Gurram 2E
Fri Nov 27, 2015 8:50 pm
Forum: Identifying Acidic & Basic Salts
Topic: Ions as Bases
Replies: 2
Views: 420

Re: Ions as Bases

Sodium is not included because it is a spectator ion, so we just tend to leave it out.
by Sandeep Gurram 2E
Fri Nov 27, 2015 8:48 pm
Forum: Lewis Acids & Bases
Topic: Acid and Base Neutralization
Replies: 1
Views: 382

Acid and Base Neutralization

In order for acids and bases to neutralize each other, do they have to have the relatively close amounts to one another? Or can you have a lot of base and add a little acid to neutralize the two? (or vice versa).
by Sandeep Gurram 2E
Mon Nov 16, 2015 11:26 pm
Forum: Naming
Topic: Drawing ICE box
Replies: 1
Views: 311

Re: Drawing ICE box

This is when calculating reaction quotient (Q c ) is very helpful. Remember, you use the same process to calculate Q c as you do to calculate the equilibrium constant. As Dr. Lavelle has outlined in class, if the reaction quotient is less than the equilibrium constant, (Q c < K c ) then the reaction...
by Sandeep Gurram 2E
Mon Nov 16, 2015 11:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Table
Replies: 1
Views: 187

Re: ICE Table

The ice table is required when the initial molarities of reactants and or products are given, but the equilibrium molarities are not. Typically, the equilibrium constant is provided and using the ice box, you have to solve for the change in concentrations for the reactants and products.
by Sandeep Gurram 2E
Mon Nov 16, 2015 11:17 pm
Forum: Naming
Topic: Coordination Compounds
Replies: 1
Views: 327

Re: Coordination Compounds

The roman numerals after the cation name specifies the charge that the cation (central atom has). In the problem that you provided, since NH 3 has a neutral charge, we are left with two chlorines (one inside the coordination complex, and one outside). These two chlorines amount to a net -2 charge. A...
by Sandeep Gurram 2E
Sat Nov 14, 2015 7:41 pm
Forum: Naming
Topic: Alphabetical Order in Naming?
Replies: 1
Views: 324

Alphabetical Order in Naming?

Hello,

When naming a coordination compound, does a greek prefix play a role in the alphabetization? For example if a compound contained diammine and chloro, would the chloro come first since C comes before D? Or do we disregard the D and say that diammine comes before chloro? Thank You!
by Sandeep Gurram 2E
Sat Oct 31, 2015 7:01 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Dissociation Energy
Replies: 2
Views: 502

Re: Dissociation Energy

It isn't something we have to calculate, at least for this class. However, there are general rules for which bonds between atoms might be stronger than other bonds. Normally, shorter bonds are stronger than longer bonds (i.e. triple > double > single). Additionally, bonds between atoms that have lon...
by Sandeep Gurram 2E
Sat Oct 31, 2015 6:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lewis structure of SO2Cl2
Replies: 1
Views: 4385

Re: Lewis structure of SO2Cl2

Yes, according to the general rules of formal charge, if sulfur had double bonds with both oxygen atoms, the entire compound would technically be considered in a lower energy, more stable state. However, remember that formal charge is just a general set of rules you can follow, it doesn't mean that ...
by Sandeep Gurram 2E
Sun Oct 25, 2015 4:21 pm
Forum: Lewis Structures
Topic: HW #3.57b
Replies: 1
Views: 300

HW #3.57b

Why is it that in the Lewis structure of the hydrogen sulfite ion, the sulfur is not attached to hydrogen? Instead, the sulfur is attached to three oxygens and the hydrogen is attached to one of the oxygens. Why is this?
by Sandeep Gurram 2E
Fri Oct 16, 2015 5:59 pm
Forum: Ionic & Covalent Bonds
Topic: Compounds having Ionic/Covalent Characteristics
Replies: 1
Views: 445

Compounds having Ionic/Covalent Characteristics

What other properties are examined to determine whether a compound having an electronegativity between 1.5 and 2.0 is more ionic or more covalent? Professor Lavelle mentioned a compound's solubility in water can be indicative its chemical properties. Any other properties we can look at to tell wheth...
by Sandeep Gurram 2E
Fri Oct 16, 2015 5:52 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Determining principle quantum number
Replies: 1
Views: 357

Re: Determining principle quantum number

The principle quantum number is always the period the element is located in. In this case, iron would have n=4, as it is in the fourth period. Principle quantum number is unrelated to which orbital electrons are being added to.
by Sandeep Gurram 2E
Fri Oct 16, 2015 4:44 pm
Forum: Ionic & Covalent Bonds
Topic: Diatomic Molecules
Replies: 3
Views: 422

Re: Diatomic Molecules

Yes. Another shorthand phrase that is helpful for me to remember which elements are HON and the halogens. Another good one is Have No Fear Of Ice Cold Beer.
by Sandeep Gurram 2E
Fri Oct 16, 2015 4:40 pm
Forum: Resonance Structures
Topic: Stability in Resonance Structures
Replies: 1
Views: 354

Re: Stability in Resonance Structures

Resonance structures are unique in that the electrons present in the structure are delocalized, meaning that they are not associated with one particular atom or bond in the chemical structure. This state of delocalization is the reason why resonance structures are generally more stable than non-reso...
by Sandeep Gurram 2E
Sat Oct 10, 2015 12:34 am
Forum: Trends in The Periodic Table
Topic: Electron Affinity Trends
Replies: 1
Views: 283

Electron Affinity Trends

For both ionization energies and size there are general trends that have relatively few exceptions within their trends. However, electron affinities seem to be all over the place. Although it is true that the upper right elements generally have high electron affinities, there is not the same constan...
by Sandeep Gurram 2E
Sat Oct 10, 2015 12:28 am
Forum: Trends in The Periodic Table
Topic: Exceptions to Ionization energy trends?
Replies: 3
Views: 27187

Re: Exceptions to Ionization energy trends?

Bryan did a great job of explaining. Basically, there is a greater electron-electron repulsion force within the oxygen atom than there is within the nitrogen atom because the eighth electron in oxygen is paired with an electron that is already occupying an orbital. This repulsion of electrons in the...
by Sandeep Gurram 2E
Thu Oct 01, 2015 11:58 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Initial and Final Energy Levels
Replies: 1
Views: 930

Initial and Final Energy Levels

Question (1.15): In the UV 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 understand that you first have to use the λν = c formula to calc...
by Sandeep Gurram 2E
Thu Oct 01, 2015 11:41 pm
Forum: Photoelectric Effect
Topic: eV to J
Replies: 1
Views: 338

Re: eV to J

There are 1.6022 x 10^(-19) Joules for every electron volt.

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