Search found 26 matches

by Jake Ney lecture 1 discussion 1F
Sat Mar 12, 2016 4:25 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Equatorial and Axial vs Cis and Trans
Replies: 1
Views: 871

Equatorial and Axial vs Cis and Trans

How does cis and trans relate to axial and equatorial. For example if two substituents on a cyclohexane are cis does this mean that they both have to be equatorial or that they both have to be axial?. Furthermore how does this translate to drawing cis and trans substituents? Thanks.
by Jake Ney lecture 1 discussion 1F
Tue Mar 08, 2016 8:39 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: residual entropy
Replies: 1
Views: 378

Re: residual entropy

NO has two positions (N=O and O=N) which both react differently due to the different number of the electrons on N and O. BF has only one position as even when rotated the molecule is essentially the same, and interacts the same with other molecules. Because NO has more possible positions its degener...
by Jake Ney lecture 1 discussion 1F
Tue Mar 08, 2016 8:33 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Quiz 3 question
Replies: 2
Views: 516

Re: Quiz 3 question

On page 76 the course reader notes that as activation energy increases k decreases. According to the Arrhenius equation k=A*e^(-E/RT) however there can be multiple factors that change if k increases. It is possible that Ea increases as k decreases however this is not definitive. The increase in k ca...
by Jake Ney lecture 1 discussion 1F
Tue Mar 08, 2016 8:22 pm
Forum: *Aldehydes
Topic: Aldehyde Numbering
Replies: 1
Views: 671

Re: Aldehyde Numbering

No that would not be counted as wrong, although excessive that is the correct numbering.
by Jake Ney lecture 1 discussion 1F
Tue Mar 08, 2016 8:19 pm
Forum: *Cycloalkanes
Topic: Finding Bond Angles
Replies: 3
Views: 623

Re: Finding Bond Angles

I believe you divide the number of sides by 360.
by Jake Ney lecture 1 discussion 1F
Sun Feb 28, 2016 10:33 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Energy of Transitional States
Replies: 2
Views: 459

Re: Energy of Transitional States

Higher G values entails that a molecule is less disordered and therefore usually more complex. On page 88 of the course reader however TS 1 has a higher free energy barrier than TS 2 primarily because a double bond must be broken for this transition state to form.
by Jake Ney lecture 1 discussion 1F
Sun Feb 28, 2016 10:20 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Question 4.31
Replies: 1
Views: 320

Re: Question 4.31

Using the Arhenius Equation k=A*e^-E/(RT) we can determine that E is inversely proportional to k. In other words if E increases k will decrease and if E decreases k will increase. Thus we can conclude that if the activation energy of reaction 1 is larger than the activation energy of reaction two, t...
by Jake Ney lecture 1 discussion 1F
Sat Feb 20, 2016 6:55 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Calculating A for the Arrhenius Equation, quest. 15.63
Replies: 1
Views: 483

Calculating A for the Arrhenius Equation, quest. 15.63

15.63 asks: The rate constant of the reaction between CO2 and OH- in aqueous solution to give the HCO3- ion is 1.5x10^10 L/mol*s at 25 degree C. Determine the rate constant at blood temperature (37 degree C), given that the activation energy for the reaction is 38 kJ/mol*s. I'm assuming that you plu...
by Jake Ney lecture 1 discussion 1F
Sat Feb 13, 2016 6:39 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Units of Rate constant
Replies: 2
Views: 535

Re: Units of Rate constant

The units of rate constants vary by 1st, 2nd and Zero Order reactions. For First Order reactions the units are s-1 because when used in k[A] we get the correct units for d[A]/dt which is mol/L*s. For Second order reactions the units of k are in M-1s-1 because when used in the equation k[A]^2 we get ...
by Jake Ney lecture 1 discussion 1F
Sat Feb 13, 2016 2:31 pm
Forum: General Rate Laws
Topic: How to solve for time, given k and concentrations
Replies: 1
Views: 375

Re: How to solve for time, given k and concentrations

Because the he K value is given in M-1s-1 we know that we are dealing with a 2nd order reaction. Solving the question now is just a matter of plugging in the given values into the equation 1/[A]=kt+1/[Ao] => 1/[.0220 M]=(8.39M-1s-1)t+1/[.0840 M] and solving algebraically for t.
by Jake Ney lecture 1 discussion 1F
Sun Feb 07, 2016 3:46 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: Midterm 2012, Q3A
Replies: 1
Views: 431

Re: Midterm 2012, Q3A

O2 has only one possible state due to its lewis structure O=O. This is why its degeneracy, which is the number of possible states to the number of particles in that are in each state is 1. The lewis structure of BH2F has three possible states as there are three alternate positions for the fluorine a...
by Jake Ney lecture 1 discussion 1F
Sat Jan 30, 2016 10:54 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Calculating Standard Gibbs f.e. Without Temperature
Replies: 1
Views: 930

Calculating Standard Gibbs f.e. Without Temperature

Question 11.111 in the textbook asks "A certain enzyme-catalyzed reaction in a biochemical cycle has an equilibrium constant that is 10 times the equilibrium constant of the next step in the cycle. If the standard Gibbs free energy of the first reaction is -200. kJ/mol, what is the standard Gib...
by Jake Ney lecture 1 discussion 1F
Sat Jan 23, 2016 2:40 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Calculating Entropy using S=kb*ln W
Replies: 1
Views: 4716

Calculating Entropy using S=kb*ln W

Question 9.21 asks to calculate the entropy of a solid nanostructure made of 64 molecules in which the molecules (a) are all aligned in the same direction; (b) lie in any one of four orientations with the same energy. For part (a) I assume that there is only one possible state, while for part b ther...
by Jake Ney lecture 1 discussion 1F
Sat Jan 16, 2016 6:09 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.51 The enthalpy of formation of trinitrotoluene (TNT)
Replies: 2
Views: 5149

Re: 8.51 The enthalpy of formation of trinitrotoluene (TNT)

That is correct the O2 and N2 are diatomic gases in their most stable form and thus their standard enthalpy of formation is zero. Using the enthalpies of formation we calculate that CO2 requires -393.51 kJ/mol while H20 requires -241.82. Given TNT's enthalpy of formation we calculate: 28(-393.51 kJ/...
by Jake Ney lecture 1 discussion 1F
Sat Jan 09, 2016 2:25 pm
Forum: Calculating Work of Expansion
Topic: Identifying Positive Potential Energy
Replies: 1
Views: 350

Identifying Positive Potential Energy

In problem 8.3 air in a bicycle pump is compressed by pushing in the handle. According to the solutions guide this work is positive with respect to air in the pump. This seems counter intuitive because work is being done on the system. Can somebody please explain how to identify when the work with r...
by Jake Ney lecture 1 discussion 1F
Sat Dec 05, 2015 2:05 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: M.O
Replies: 1
Views: 427

M.O

In creating molecular orbital diagrams, why do molecules with an atomic number less than 8 have a notation with a Pi first in the P orbital while molecules with an atomic number greater than 8 have the Sigma orbital first? What would be the correct notation for a molecule such as C-F?
by Jake Ney lecture 1 discussion 1F
Thu Dec 03, 2015 11:27 am
Forum: General Science Questions
Topic: Fall 2010 Final Exam Question 5
Replies: 1
Views: 613

Re: Fall 2010 Final Exam Question 5

HCLO: Cl-O-H HCLO2: O ll Cl-O-H HClO3: O ll Cl-O-H ll O HClO4: O ll O=Cl-O-H ll O As these acids have an increasing number of Oxygens bonded to the central Cl, these Oxygens which are highly electronegative withdraw e- density from the Oxygen attached to the hydrogen atom. Thus as there are more oxy...
by Jake Ney lecture 1 discussion 1F
Sun Nov 29, 2015 11:49 pm
Forum: Bronsted Acids & Bases
Topic: Disassociation of Acids vs Their Conjugate Bases
Replies: 1
Views: 400

Disassociation of Acids vs Their Conjugate Bases

For problem 12.107 does a strong acid or its conjugate base disassociate more hydronium/hydroxide ions? Furthermore how does the PKa or PKb of a solution correlate with the strength of the acid or its conjugate base?
by Jake Ney lecture 1 discussion 1F
Thu Nov 19, 2015 10:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding Equations Given Partial Pressures
Replies: 2
Views: 776

Re: Finding Equations Given Partial Pressures

For A, the total change in pressure is calculated from the graph as 27.5-17.5=10 kPa. For B, the total change in pressure is 10 while for C this value is 5. This gives us a ratio of 2kPa A: 2 kPa B: 1kPa C. We use this ratio to formulate the balanced chemical equation 2A(g) --> 1B(g) + 2C(g) . (We k...
by Jake Ney lecture 1 discussion 1F
Sat Nov 14, 2015 2:58 pm
Forum: Ideal Gases
Topic: Exothermic and Endothermic Reactions
Replies: 3
Views: 852

Re: Exothermic and Endothermic Reactions

Endothermic reactions absorb heat or energy from the environment and therefore require an input of energy. Exothermic reactions release heat onto the environment and are signified by a negative change in enthalpy -(ΔH).
by Jake Ney lecture 1 discussion 1F
Sat Nov 07, 2015 5:20 pm
Forum: Photoelectric Effect
Topic: Work Function vs De Broglie
Replies: 4
Views: 3205

Re: Work Function vs De Broglie

First, finding the de broglie wavelength of an object or particle involves calculating its momentum and h/p. This has nothing to do with the photoelectric effect. Second you often have to use E=hv in a problem involving the photoelectric effect to calculate the work function of a metal surface or to...
by Jake Ney lecture 1 discussion 1F
Sat Oct 31, 2015 12:35 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bond Order
Replies: 3
Views: 1194

Re: Bond Order

No, when you draw the molecular orbital the bonding region is always going to be lower in energy than the anti-bonding region. Thus the bonding regions will always fill up with more elections than the anti-bonding region.
by Jake Ney lecture 1 discussion 1F
Sun Oct 25, 2015 4:24 pm
Forum: Hybridization
Topic: Chapter 4 question 1 help please
Replies: 2
Views: 476

Re: Chapter 4 question 1 help please

For the first molecule there must be a pair of lone electrons bending the two non-central atoms to an angle less than 180 degrees. With AX2E VESPR models the angles are typically less than 120 degrees but it is more important to note the non-linear, bent shape. For the second molecule there may be l...
by Jake Ney lecture 1 discussion 1F
Sat Oct 17, 2015 5:15 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge and Coulombic Attraction
Replies: 1
Views: 500

Formal Charge and Coulombic Attraction

Is it necessary to calculate the formal charge of two molecules to determine their coulombic attraction to one another? Furthermore how do you calculate the coulombic attraction of an ion to a solid?
by Jake Ney lecture 1 discussion 1F
Fri Oct 09, 2015 4:47 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence-Shell Configurations
Replies: 1
Views: 415

Valence-Shell Configurations

Problem 2.55 asks to give the notion for valence shell configurations for entire groups such as the Alkali Earth metals. Can someone please explain how to determine the valence shell configurations for different groups and how these configurations relate to electron configurations?
by Jake Ney lecture 1 discussion 1F
Fri Oct 02, 2015 12:47 am
Forum: Einstein Equation
Topic: The value of Planck's Constant
Replies: 3
Views: 1273

Re: The value of Planck's Constant

Planck's constant was determined empirically as experiments relating frequency to energy reveal the value of this constant. If you were to plot a graph of energy versus frequency in which the y-axis was labeled Energy and the x-axis was labeled frequency you would get a straight line with a slope of...

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