Search found 41 matches

by Erin 2I
Wed Mar 09, 2016 8:26 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Kinetic/Thermodynamic Stability
Replies: 1
Views: 410

Kinetic/Thermodynamic Stability

What are the qualities of reactions that are
1.kinetically stable
2.kinetically unstable
3.thermodynamically stable
4.thermodynamically unstable
by Erin 2I
Wed Mar 09, 2016 8:24 pm
Forum: *Haloalkanes
Topic: Priority in numbering vs. double/triple bonds
Replies: 1
Views: 719

Priority in numbering vs. double/triple bonds

Is it true that double/triple bonds have priority in numbering over hallides?
by Erin 2I
Mon Mar 07, 2016 11:03 am
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Stability and strain
Replies: 1
Views: 422

Re: Stability and strain

Yes, the more a molecule is staggered, the more stable it is.
Yes, torsional strain will increase potential energy, since it will make the more unstable (and more unstable molecules have higher potential energy)
by Erin 2I
Wed Mar 02, 2016 4:29 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Steady State Eq
Replies: 1
Views: 224

Steady State Eq

do we have to know how to do the steady state eq?
by Erin 2I
Sun Feb 28, 2016 6:01 pm
Forum: *Electrophiles
Topic: Aryl and Alkyl
Replies: 1
Views: 338

Aryl and Alkyl

Hi, I was wondering what aryl carbanions and an alkyl carbanions were?
by Erin 2I
Mon Feb 15, 2016 9:29 pm
Forum: General Rate Laws
Topic: Rate Orders
Replies: 1
Views: 253

Re: Rate Orders

If something is 0th order, there will be no effect on the rate when the concentration increases or decreases. If something is 1st order, there is a linear relationship between the concentration and the rate. This means that if the concentration doubles, the rate will double. If the concentration tri...
by Erin 2I
Tue Feb 09, 2016 11:41 pm
Forum: Calculating Work of Expansion
Topic: Change in moles
Replies: 1
Views: 381

Change in moles

Hi, for the 2015 midterm #2 part a, we were asked to find the work of the reaction CH 3 CH 2 I(g) + H 2 O(g) --> CH 3 CH 2 OH(g) + HI(g) The reaction happens under constant pressure, 1 atm, and room temperature 25˚C. 36.00 g of H2O(g) is converted to ethanol and HI gas completely. The answer says th...
by Erin 2I
Tue Feb 09, 2016 4:07 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy of Vaporization
Replies: 1
Views: 355

Entropy of Vaporization

Hypothetically, if we were asked to find the entropy of vaporizing a solid at a temperature below the boiling point (for example, -5˚C), would we have to find the entropy of raising the temperature to 0˚C, then the entropy of fusion, then the entropy of raising the temperature to 100˚C, then the ent...
by Erin 2I
Mon Feb 08, 2016 9:31 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Balancing equations
Replies: 1
Views: 366

Balancing equations

The question I had a problem with says: Although rockets operate under conditions that are far from standard, an initial estimation of the potential of a rocket fuel might assess whether its oxidation at the high temperatures reached in a rocket is spontaneous. A chemist exploring potential fuels fo...
by Erin 2I
Sun Feb 07, 2016 5:03 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cells
Replies: 1
Views: 308

Concentration Cells

Hi, the question I have problems with reads, If you were to construct a concentration cell in which one half cell contains 1.0 M CrCl 3 and the other half cell 0.0010 M CrCl 3 , and both electrodes were chromium, at which electrode would reduction spontaneously take place? In our course reader, it s...
by Erin 2I
Fri Feb 05, 2016 10:38 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: assigning half reactions to oxidation/reduction
Replies: 1
Views: 394

assigning half reactions to oxidation/reduction

For number 14.37, we need to determine the potential of the following cell: Pt(s) | Cl 2 (g) | HCl(aq) || HCl(aq) | H 2 (g) | Pt(s) The two half reactions are Cl 2 + 2e - --> 2C - E˚ = +1.36 2H + + 2e - --> H 2 E˚ = 0 The book says that the cathode will be H reaction, and the anode will be the Cl re...
by Erin 2I
Fri Feb 05, 2016 10:18 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.35 discrepancy with constants
Replies: 2
Views: 395

14.35 discrepancy with constants

Hello Question 35 asks, Determine the equilibrium constants for the following reactions Mn(s) + Ti 2+ (aq) <--> Mn 2+ + Ti I successfully calculated the Eo of the cell, which was -.45 V. However, when I plugged in RT/nF, I got a number that was incorrect. For R, I used 8.314 For T, I used 298 For n,...
by Erin 2I
Fri Feb 05, 2016 10:13 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: which half reaction to use
Replies: 2
Views: 456

which half reaction to use

For 14.17, we are asked to write the balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(II) chloride. How do we know which half reaction to use since we are given 4 different types (i.e. K+, MnO4-, Fe2+, Cl-)?
by Erin 2I
Mon Feb 01, 2016 11:14 pm
Forum: Balancing Redox Reactions
Topic: Confusion on cathode and anode reactions HW 14.15
Replies: 1
Views: 572

Re: Confusion on cathode and anode reactions HW 14.15

The solid silver forms when Ag+ (aq) receives and electron, forming just Ag. Ag naturally is a solid, so when it gains an electron (undergoing reduction), it will plate the electrode with solid Ag. I am not sure if the question specifies whether the electrode ITSELF is made of pure Ag. It can be, bu...
by Erin 2I
Mon Feb 01, 2016 10:55 pm
Forum: Balancing Redox Reactions
Topic: Identifying Oxidizing Agent and Reducing Agent
Replies: 3
Views: 460

Re: Identifying Oxidizing Agent and Reducing Agent

I believe the oxidizing AGENT is the one being reduced, and the reducing AGENT is the one being oxidized. The ion being reduced is oxidizing the other, and vice versa
by Erin 2I
Mon Feb 01, 2016 10:31 pm
Forum: Balancing Redox Reactions
Topic: Electromotive Force
Replies: 2
Views: 414

Re: Electromotive Force

The electromotive force is the voltage difference between the two cells.
The E is maximum when there is no current, because when current starts to flow, then the difference in voltage between the cells will start to decrease, as the concentrations of the two cells will start to reach equilibrium.
by Erin 2I
Tue Jan 26, 2016 3:32 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Q in constant p and constant v
Replies: 2
Views: 479

Re: Q in constant p and constant v

q = (mass) \cdot C\cdot \Delta T C here is the specific heat capacity, which is constant. There is also q = (mole)\cdot C\cdot \Delta T The C here is the molar heat capacity, which is also constant. It should be noted that for all ideal gases, the molar heat capacity is \frac{5}{2}R...
by Erin 2I
Mon Jan 18, 2016 3:41 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Unit kJ vs kJ per mole
Replies: 1
Views: 439

Unit kJ vs kJ per mole

Hello,

I was confused as to when we just use kJ, and when we have to use kJ per mole?
Does it matter if we just put kJ?
by Erin 2I
Sat Jan 16, 2016 6:13 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimetry and delta T (homework problem 8.19)
Replies: 2
Views: 553

Re: Calorimetry and delta T (homework problem 8.19)

The tea kettle will be receiving the same amount of heat as the water, so the change in temperature should be the same
by Erin 2I
Tue Jan 05, 2016 10:20 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calculating energy changes when heating an ideal gas
Replies: 1
Views: 425

Calculating energy changes when heating an ideal gas

This is example 8.6 from the textbook, and the question asks, "Calculate the final temperature and the change in internal energy when 500. J of energy is transferred as heat to 0.900 mol O2 at 298K and 1.00 atm at a)constant volume; b)constant pressure. Treat the gas as ideal." The book so...
by Erin 2I
Fri Dec 04, 2015 3:46 pm
Forum: General Science Questions
Topic: Deriving Equations
Replies: 2
Views: 2559

Re: Deriving Equations

It asked about De Broglie's equation, or the equation
pOH = 14 - pKa - log (base)/(acid)
by Erin 2I
Fri Dec 04, 2015 3:03 am
Forum: General Science Questions
Topic: Deriving Equations
Replies: 2
Views: 2559

Deriving Equations

Hello. I noticed that there a few number of questions on past finals that ask to derive equations. I was wondering which equations we should know how to derive?
by Erin 2I
Mon Nov 30, 2015 8:56 pm
Forum: Bronsted Acids & Bases
Topic: Formic Acid vs. Acetic Acid
Replies: 2
Views: 468

Re: Formic Acid vs. Acetic Acid

CH3 is a ligand on the carbon chain, so it does not have one unpaired electron though..
by Erin 2I
Mon Nov 30, 2015 9:18 am
Forum: Bronsted Acids & Bases
Topic: Formic Acid vs. Acetic Acid
Replies: 2
Views: 468

Formic Acid vs. Acetic Acid

On homework 12.53 part b, we were given two acids, formic and acetic, and were asked which one is stronger and why. The solutions manual says that formic acid is stronger because the CH3 ligand in the acetic acid has electron donating properties, and is therefore less electron withdrawing. I had a h...
by Erin 2I
Fri Nov 27, 2015 4:17 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Determining pH given 2 Ka Values
Replies: 2
Views: 9520

Re: Determining pH given 2 Ka Values

I thought that when you look for the pH that involves two K values, we find the concentration of H+ from the first equilibrium, and the concentration of H+ from the second equilibrium. The total pH would be -log of the addition of both H+ concentrations
by Erin 2I
Tue Nov 17, 2015 1:30 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: "New Initial"
Replies: 3
Views: 294

Re: "New Initial"

I see. Then how do we know when to push the equilibrium all the way to the reactants side to make calculations easier?

Thank you
by Erin 2I
Mon Nov 16, 2015 3:38 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K for gases
Replies: 1
Views: 215

K for gases

Given a homogeneous chemical equilibrium equation with gases, and the question asks for an expression of K, do we automatically assume that it is asking for the expression of pressures? Will it be wrong to give the expression of concentrations?
by Erin 2I
Mon Nov 16, 2015 12:01 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Gibb's Free Energy
Replies: 1
Views: 210

Gibb's Free Energy

Hello,
For 11.29 we were required to use Gibb's Free Energy to find the value of K. Do we need to know how to use Gibb's Free Energy for the quiz/final?
by Erin 2I
Sun Nov 15, 2015 11:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: "New Initial"
Replies: 3
Views: 294

"New Initial"

Hello, My question regards problem #67 for Chapter 11. "The reaction 2HCl (g) \rightleftharpoons H 2 (g) + Cl 2 (g) has K = 3.2 x 10 -34 at 298 K. The initial partial pressures are H 2 , 1.0 bar; HCl, 2.0 bar; and Cl 2 , 3.0 bar. At equilibrium there is 1.0 mol H 2 (g)l What is the volume of th...
by Erin 2I
Tue Nov 10, 2015 1:04 am
Forum: Naming
Topic: Important Ligand Names
Replies: 1
Views: 213

Important Ligand Names

Hello,
Dr. Lavelle provided a chart of the names of ligands. Do we have to memorize all of these, or are there a few key ones we should know? And if there are a few key ones we should know, which ones are they?

Thank you
by Erin 2I
Mon Nov 02, 2015 12:33 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty in position
Replies: 5
Views: 855

Uncertainty in position

For Quiz 1, Question 4, it says that the electron is confined to the size of an aluminum atom of radius = 125 pm. When we use the Heisenberg Uncertainty equation, do we have to double the radius for ??
by Erin 2I
Mon Nov 02, 2015 12:18 am
Forum: Lewis Structures
Topic: Lowest Ionization Energy Atom as the Central Atom
Replies: 2
Views: 526

Lowest Ionization Energy Atom as the Central Atom

For compounds like ClBr 4 - and ArCl 4 Cl and Ar are both atoms with the higher ionization energy. But it seems to make more sense to me that they be the central atom for some reason. Which are the central atom in these cases, and does the ionization rule for the central atom have exceptions? And if...
by Erin 2I
Sun Nov 01, 2015 7:16 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration for Cr^2+
Replies: 2
Views: 7355

Electron Configuration for Cr^2+

The correct electron configuration for Cr 2+ is said to be [Ar]3d 4 . I thought that in general, we move the s electrons to the d when we want to make the d shell half or completely filled. But in this case, moving the 4s electrons will not even make the d shell half filled. So, how do we know when ...
by Erin 2I
Sun Nov 01, 2015 6:46 pm
Forum: Properties of Electrons
Topic: Emission Spectrum differences for different atoms
Replies: 1
Views: 1456

Emission Spectrum differences for different atoms

My question refers to the 2006 MT Q2. "The electron in a hydrogen atom is excited to a 4d orbital. Calculate the energy of the photon released if the elctron were then to move to 1s, 2p, 2s, and 4s. If the outermost electron in a potassium atom were excited to a 4d orbital and then fell to the ...
by Erin 2I
Sat Oct 31, 2015 7:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dimers
Replies: 1
Views: 256

Dimers

Hello,
I noticed there are many questions toward the end of chapter 4 that required us to figure out the shapes of dimers. Are we required to know how to do dimers for the exam?

Thank you.
by Erin 2I
Sun Oct 25, 2015 12:23 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Precise Bond Angles
Replies: 1
Views: 313

Precise Bond Angles

In high school, my teacher gave us exact bond angles for shapes like see saw. However, the answer key gives angles with >120 or such. On the quiz, will the answer be wrong if we give exact bond angles? Do we have to give our answers as an inequality? Thank you.
by Erin 2I
Sun Oct 18, 2015 1:12 am
Forum: Empirical & Molecular Formulas
Topic: Hydrocarbons in Combustion
Replies: 5
Views: 877

Re: Hydrocarbons in Combustion

If the question specifies that the reactant is a "hydrocarbon," then the reactant will only contain C and H. If the question does not specify that it is a "hydrocarbon," and you are given the masses of the products CO2 and H2O, then you should start by finding the grams of C and ...
by Erin 2I
Sat Oct 10, 2015 10:47 pm
Forum: Empirical & Molecular Formulas
Topic: Hydrocarbons in Combustion
Replies: 5
Views: 877

Re: Hydrocarbons in Combustion

Thank you. The first question was from the Chem 14A Workbook from Fall 2014, #1 of the Fall 2012 Quiz.
by Erin 2I
Sat Oct 10, 2015 6:45 pm
Forum: Empirical & Molecular Formulas
Topic: Hydrocarbons in Combustion
Replies: 5
Views: 877

Hydrocarbons in Combustion

My question involves two different problems: 1. A .2500 g sample of a compound known to contain carbon, hydrogen, and oxygen undergoes complete combustion to produce 0.3664 g of CO2 and 0.1500 g of H2O. What is the empirical formula of this compound? The molar mass of the hydrocarbon is 180.16 g/mol...
by Erin 2I
Sat Oct 10, 2015 6:26 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Plugging in the value of velocity
Replies: 1
Views: 348

Plugging in the value of velocity

This is the problem related to my question: What is the uncertainty of position of a 10.0 g toy car that is traveling at \pm 1 ms^{-1} ? What is the uncertainty of position of an electron traveling at the same speed? I understand that we use Heisenberg's indeterminacy equation. The answer key uses 2...
by Erin 2I
Fri Oct 02, 2015 1:09 am
Forum: Properties of Light
Topic: EM Radiation spectrum
Replies: 1
Views: 250

EM Radiation spectrum

Hello,
Will we need to memorize the general range of frequencies/wavelengths of the EM radiation spectrum?

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