Search found 37 matches
- Mon Mar 07, 2016 6:03 am
- Forum: *Cycloalkanes
- Topic: cycloalkanes vs alkenes
- Replies: 2
- Views: 678
Re: cycloalkanes vs alkenes
If given the chemical formula, any double or triple bonds would be indicated. So rather than CH3CH3 it would be CH3=CH3 for a double bond. With that being said, yes it does matter if you draw one over the other, as you would draw a cycloalkane if there were only single bonds and an alkene if there w...
- Fri Mar 04, 2016 7:15 pm
- Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
- Topic: Relieving Torsional Strain
- Replies: 1
- Views: 587
Relieving Torsional Strain
Recalling wednesday's lecture, Dr. Lavelle described relieving torsional strain by rotation. First of all, just to make sure, the strain is caused by the eclipsed conformation right? And to relieve said strain, the rotation Dr. Lavelle was talking about would be the rotation to go from a Eclipsed co...
- Sun Feb 28, 2016 11:39 am
- Forum: *Alkenes
- Topic: Benzene vs Phenyl
- Replies: 2
- Views: 1423
Re: Benzene vs Phenyl
Hey, Benzene refers to a specific ring molecule C6H6 with alternating double and single molecules, where as Phenyl refers to the category of functinal groups that essentially looks like benzene, but instead of being actual benzene, one of the hydrogens is replaced with a bond to the parent molecule/...
- Sun Feb 28, 2016 11:33 am
- Forum: *Cyclopropanes and Cyclobutanes
- Topic: Bond Angle Strain vs. Torsional Strain
- Replies: 8
- Views: 3414
Re: Bond Angle Strain vs. Torsional Strain
Hey, I'm not sure we need to know this distinction since it seems like this is 14C material, but here's a UCLA resource (I think it's actually from Hardinger's class) that could help clarify the distinction between the two types of strains. http://www.chem.ucla.edu/harding/notes/strain_02.pdf"onclic...
- Sun Feb 28, 2016 11:22 am
- Forum: *Alkanes
- Topic: Quiz 3 preparation: practice quiz 1.2--possible error?
- Replies: 1
- Views: 530
Re: Quiz 3 preparation: practice quiz 1.2--possible error?
Hey,
Really lackluster response, but simply, yes, I agree with you! The ethyl should come before the (tri)methyl. Or in any case, the ethyl should always come before the methyl in terms of the naming.
Really lackluster response, but simply, yes, I agree with you! The ethyl should come before the (tri)methyl. Or in any case, the ethyl should always come before the methyl in terms of the naming.
- Wed Feb 17, 2016 3:54 pm
- Forum: General Rate Laws
- Topic: Stoichiometric coefficients and rate laws
- Replies: 1
- Views: 678
Re: Stoichiometric coefficients and rate laws
I don't think the stoichiometric coefficients are very important in determining the order of the reaction; I think you just compare the rates based on changes in the concentrations. This is because when you're comparing rates, the rates themselves already incorporate the stoichiometric coefficients,...
- Mon Feb 15, 2016 9:19 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Activation Energy and Temperature
- Replies: 1
- Views: 714
Re: Activation Energy and Temperature
Technically, there is no relationship between temperature and activation energy, the temperature doesn't affect the amount of activation energy that is need for the reaction to occur. However, when you start off at a higher temperature, the reactants naturally start of with more energy (temperature ...
- Mon Feb 15, 2016 9:14 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: What affects reaction rates?
- Replies: 2
- Views: 651
Re: What affects reaction rates?
There are many factors that can affect reaction rates, such as concentration of the reactants, the temperature in which the reaction takes place, and the phase and surface area of the reactants at the time the reaction takes place(which I don't think we need to account for/worry about).
- Sat Feb 06, 2016 8:05 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Midterm 2011 2B
- Replies: 2
- Views: 767
Re: Midterm 2011 2B
Hey! My TA actually warned me about this earlier and I think I can help! Basically, the problem is being tricky here, where it is stating that there is 1mol of the element, and that element is in the form of a monatomic or diatomic gas. This means that for the diatomic gas, there are essentially hal...
- Sat Jan 30, 2016 11:45 pm
- Forum: Balancing Redox Reactions
- Topic: Redox reactions in Basic or Acidic conditions
- Replies: 3
- Views: 3392
Re: Redox reactions in Basic or Acidic conditions
you should be told if the reaction is in an acid or a base.
- Sat Jan 30, 2016 6:23 pm
- Forum: Balancing Redox Reactions
- Topic: Redox reactions in Basic or Acidic conditions
- Replies: 3
- Views: 3392
Re: Redox reactions in Basic or Acidic conditions
Hi there! So the only difference between reactions in basic and acidic conditions is that blaancing reactions in a base, you would first balance it like how you would in an acid, but since you're in a basic solution now, you would add enough OH- to both sides of the equation to neutralize the H+. So...
- Wed Jan 27, 2016 3:32 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: ΔU=0 in Isothermal Process
- Replies: 1
- Views: 777
Re: ΔU=0 in Isothermal Process
As Dr. Lavelle addressed in class, looking at your question strictly mathematically, recall that delta U, change in internal energy, is also equal to 3/2nRdeltaT. So when the process is isothermal, indicating no change in T and therefore a delta T of 0, then essentially we have delta U=3/2nR(0), whi...
- Wed Jan 27, 2016 3:24 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Specific Heat Sig Figs
- Replies: 1
- Views: 4142
Re: Specific Heat Sig Figs
I think that although it is a pre-determined valued, these given values have probably been tested and calculated the many more sig figs, however, what we are given are usually the values rounded to a certain number of sig figs. Therefore, I do think that we have to do account for sig figs in Specifi...
- Sun Jan 17, 2016 3:39 pm
- Forum: Phase Changes & Related Calculations
- Topic: Isolated Systems
- Replies: 2
- Views: 590
Re: Isolated Systems
That's because no heat nor any matter is being lost or added to the system. This is described the law of conservation of energy, which states that the total energy of an isolated system is constant. Although energy can change forms, an example being mechanical to thermal, it can't be created nor des...
- Sun Jan 17, 2016 3:24 pm
- Forum: Phase Changes & Related Calculations
- Topic: Systems at constant pressure
- Replies: 1
- Views: 563
Re: Systems at constant pressure
I don't think it matters if the internal pressure is equal to the outside pressue, all that matters is that when it says pressure is constant it means that for the system that you're working with, the pressure of that system is constant. Atleast I think that's the only thing you can assume from that...
- Sun Jan 10, 2016 9:48 pm
- Forum: Phase Changes & Related Calculations
- Topic: Change in Enthalpy from Reactants to Products
- Replies: 1
- Views: 620
Re: Change in Enthalpy from Reactants to Products
There are three ways: 1. Using Hess's law and using the standard change in enthalpies for different but similar reaction and using substitution and such like shown in the course reader example, we can find the change of enthalpy for the specific reaction we're looking for. 2. We can look at individu...
- Fri Dec 04, 2015 4:10 pm
- Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
- Topic: Henderson-Hasselbach Equation
- Replies: 3
- Views: 1378
Re: Henderson-Hasselbach Equation
I'm glad it did! To explain further: You know when it's a buffer when it's a weak acid and it's conjugate base or when it's a weak base and it's conjugate acid. I thinkt here's more clarification on page 156 of the course reader, where it's explained what a buffer is and actually uses the Henderson ...
- Fri Dec 04, 2015 7:23 am
- Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
- Topic: Henderson-Hasselbach Equation
- Replies: 3
- Views: 1378
Re: Henderson-Hasselbach Equation
I don't the knowing the derivation of the equation is very important, but it is very important that you know when to use it. In most acid-base reactions, we would typically just calculate what we need using ICE boxes. However, to get the pH of buffer solutions, we use the Henderson Hasselbach (if yo...
- Mon Nov 30, 2015 3:11 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Acid strength-HClO4 vs H3PO4 (HW 12.51d)
- Replies: 2
- Views: 5135
Re: Acid strength-HClO4 vs H3PO4 (HW 12.51d)
In this case, I think you just have to know that perchloric acid is a strong acid so it dissociates completely in an aqueous solution while phosporic acid simply does not as it is a weak acid. Sorry if I can't come up with a better explanation but I think this one of those more black and white answe...
- Mon Nov 30, 2015 3:01 am
- Forum: Polyprotic Acids & Bases
- Topic: How to identify a polyprotic acid/base
- Replies: 1
- Views: 13504
Re: How to identify a polyprotic acid/base
I don't think there's a general trend that we need to known regarding which elements can form polyprotic acids/bases. However, I think the rather we should just be familiar with the common ones, some being: http://wps.prenhall.com/wps/media/objects/3312/3392119/imag1606/TB16_003.GIF As for the secon...
- Sun Nov 22, 2015 10:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: new initial for an ICE box
- Replies: 1
- Views: 476
Re: new initial for an ICE box
Essentially, what they were trying to accomplish was removing a "number - x" and instead just having an "x" from the equilibrium calculations. They did so by shifting the equation left to favor the reactants, so it consumed the only mole of H2 and also one mole of CI2 (done by lo...
- Sun Nov 22, 2015 10:14 pm
- Forum: Ideal Gases
- Topic: When is K small enough to make the assumption
- Replies: 2
- Views: 980
Re: When is K small enough to make the assumption
Ok, in high school I learned that 10^-4 and greater is ok to make the assumption because when you work the problem out with sig figs, the number itself is enough doesn't have an impact on the final rounded number. However, I asked my TA, Andy Smaligo, just to make sure and he said that for the the p...
- Sun Nov 22, 2015 10:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Partial Pressures
- Replies: 1
- Views: 529
Re: Partial Pressures
From my experience doing all the homework problems, I think either one is ok. Just make sure you use the right gas constant if you're using PV=NRT to convert from moles per liter to pressure.
- Mon Nov 16, 2015 3:42 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: question on 11.55
- Replies: 3
- Views: 736
Re: question on 11.55
Sorry, perhaps it was due to my typo within the question, but I was asking about functions with a cubic power and higher, such as this question, which involves a power of 5.
- Mon Nov 16, 2015 4:32 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: question on 11.55
- Replies: 3
- Views: 736
question on 11.55
For question 11.5, to solve for the equilibrium concentrations I believe we need a graphing calculator, however are we allowed to use graphing calculators for the upcoming quiz?
- Sun Nov 15, 2015 7:04 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Favorable physical conditions
- Replies: 1
- Views: 589
Re: Favorable physical conditions
Hi there! Given the equation already at a state of equilibrium, you essentially look at any change in pressure when looking at how the equilibrium would shift at different conditions. If pressure within the closed environment/container increased, the equation would shift to produce the molecule rath...
- Tue Nov 10, 2015 2:55 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Small Amount of K
- Replies: 2
- Views: 426
Re: Small Amount of K
Hi! I'm slightly confused as to what you're specifically asking, but I hope I can clarify and add some explanation as to the whole "x" variabe and how we can assume that it's essentially 0. We use a general variable "x" because honestly, it doesn't matter what variable we pick, a...
- Mon Nov 02, 2015 9:28 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Drawing Heteronuclear MO diagrams
- Replies: 1
- Views: 382
Drawing Heteronuclear MO diagrams
When drawing these diagrams, is it enough just to make sure than the more electronegative atom's orbitals are drawn visibly lower than the other atom's orbitals? Or are there any other specifications, like if one has to be drawn a specific distnace lower?
- Mon Nov 02, 2015 9:17 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: H-F Diagram
- Replies: 4
- Views: 1811
Re: H-F Diagram
I thought that we had to know how to do them, weren't heteronuclear MO diagrams covered in Friday's lecture? I'm pretty sure that they aren't too much different from homonuclear diatomic molecules though, just that the atomic orbitals of the atom with a higher electronegativity needs to be drawn vis...
- Sun Nov 01, 2015 1:59 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Ionization Energy
- Replies: 1
- Views: 432
Re: Ionization Energy
If you think of this answer in terms of the atomic diagram, the the further away the electron is from the nucleus, the easier it is to remove it from the atom. Therefore, when it is in a higher molecular orbital, it is farther from the positive nucleus (repelled further by the electrons other than t...
- Sun Nov 01, 2015 1:49 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: H-F Diagram
- Replies: 4
- Views: 1811
Re: H-F Diagram
Here it is attached in the image!
- Mon Oct 26, 2015 12:05 am
- Forum: Bond Lengths & Energies
- Topic: Solution Manual Typo for 3.89 b
- Replies: 1
- Views: 525
Solution Manual Typo for 3.89 b
I think I see a typo for question 3.89 in the explanation for part b as to why the bond length between carbon and nitrogen is 142 rather than 152. The sentence reads as "However, because the C atom is involved in *page break* pm), and the N single bond radius gives 142, which is close to the ex...
- Sun Oct 25, 2015 10:57 pm
- Forum: Dipole Moments
- Topic: "Polarizing Power" Trends
- Replies: 1
- Views: 912
"Polarizing Power" Trends
What are the trends for polarizing power? From question 81 in Chapter 3, I inferred that for cations, the smaller the Cation, the greater the polarizing power. Is it the same for Anions?
- Mon Oct 19, 2015 1:15 am
- Forum: Resonance Structures
- Topic: Resonance hybrids of covalent and ionic structures
- Replies: 1
- Views: 643
Re: Resonance hybrids of covalent and ionic structures
I think based on what Dr. Lavelle explained in the lecture, it's based on whether there are double or triple bonds. I think the part of the structure with the double or triple bond contributes more to the resonance.
- Mon Oct 19, 2015 1:03 am
- Forum: Ionic & Covalent Bonds
- Topic: Ground State Electron Configuration for Ions
- Replies: 3
- Views: 1329
Re: Ground State Electron Configuration for Ions
Honestly, it shouldn't matter what version you put. Either shows your understanding of the number of electrons after being ionized.
- Sun Oct 11, 2015 2:25 pm
- Forum: Properties of Light
- Topic: How to increase the intensity of the photon
- Replies: 6
- Views: 2415
Re: How to increase the intensity of the photon
As Dr. Lavelle said, the intensity is directly proportional to the number of electrons, so you can't increase the intensity, but rather you increase the intensity of the light ray by increasing the number of photons. Also, in your initial statement before your question, isn't the opposite true? Once...
- Sat Oct 03, 2015 2:03 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 2999188
Re: Chemistry Jokes
If H20 is water, what is H204?
Drinking, bathing, washing, swimming, etc.
If H2O is the formula for water, what is the formula for ice?
H2O cubed.
Anyone know any jokes about the element sodium?
Na.
Drinking, bathing, washing, swimming, etc.
If H2O is the formula for water, what is the formula for ice?
H2O cubed.
Anyone know any jokes about the element sodium?
Na.