Search found 59 matches
- Sat Mar 17, 2018 11:13 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 2008 Practice Final Q3D
- Replies: 1
- Views: 401
Re: 2008 Practice Final Q3D
it is given that 1E-16 is the molarity of cu2+ in the question and since cu2+ is the reactant, you put its concentration in the denominator
- Sat Mar 17, 2018 10:53 am
- Forum: First Order Reactions
- Topic: Slope of 1st order RXNs
- Replies: 9
- Views: 1272
Re: Slope of 1st order RXNs
remember only the second order has a positive k slope
- Sat Mar 17, 2018 10:51 am
- Forum: Phase Changes & Related Calculations
- Topic: Test #1
- Replies: 4
- Views: 615
Re: Test #1
if you were going from gas to liquid, then it would be exothermic because phase changes of vaporization and condensation are the opposite
- Mon Mar 12, 2018 8:51 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: Functional Groups
- Replies: 7
- Views: 2057
Re: Functional Groups
you should be able to look at a complex molecule and identify which functional groups are in it
- Mon Mar 12, 2018 8:47 pm
- Forum: First Order Reactions
- Topic: Pseudo First Order Reaction
- Replies: 7
- Views: 1683
Re: Pseudo First Order Reaction
do we have to know how to apply a psuedo first order reaction or just understand it conceptually?
- Mon Mar 12, 2018 8:44 pm
- Forum: *Enzyme Kinetics
- Topic: Catalyst
- Replies: 6
- Views: 903
Re: Catalyst
the catalyst is in the reactant side of the first step and in one of the other steps it is on the reactant side, so it is used
- Wed Mar 07, 2018 9:26 pm
- Forum: General Rate Laws
- Topic: 15.13
- Replies: 4
- Views: 637
Re: 15.13
the reaction vessel is 750 mL so use this to find the molarity of H2 and I2 to find moles per liter
- Wed Mar 07, 2018 9:22 pm
- Forum: General Rate Laws
- Topic: Units
- Replies: 11
- Views: 1437
Re: Units
use the units for k requested in the question because sometimes it asks per second and sometime it asks per minute
- Wed Mar 07, 2018 9:21 pm
- Forum: First Order Reactions
- Topic: half-lives of first order versus second order
- Replies: 3
- Views: 541
Re: half-lives of first order versus second order
for ln(1/2) and ln(2/1), they give the same value, just one is negative and one is positive, if that helps
- Fri Mar 02, 2018 9:17 pm
- Forum: Zero Order Reactions
- Topic: Difference between zero, first, second [ENDORSED]
- Replies: 3
- Views: 2408
Difference between zero, first, second [ENDORSED]
What is the difference between the zero, first, and second reactions? i still dont really get it
- Fri Mar 02, 2018 5:35 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Quiz 3
- Replies: 6
- Views: 818
Quiz 3
Are we only being tested on problems that have to do with material up to #39 for quiz 3?
- Fri Mar 02, 2018 5:33 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: How to tell difference btwn thermo and kinetics [ENDORSED]
- Replies: 7
- Views: 1002
How to tell difference btwn thermo and kinetics [ENDORSED]
How do you tell if the reaction is controlled by thermodynamics? by kinetics?
- Thu Feb 22, 2018 10:02 am
- Forum: Balancing Redox Reactions
- Topic: Balancing REDOX reactions
- Replies: 5
- Views: 667
Re: Balancing REDOX reactions
remember not to multiply E by a factor when you are balancing the equations. Unlike H and S, you do not multiply E by the coefficients you use to balance the equations, since E is intensive.
- Mon Feb 19, 2018 4:53 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: how to write a cell diagram [ENDORSED]
- Replies: 7
- Views: 2011
how to write a cell diagram [ENDORSED]
what is the order in which we are supposed to write the cell diagram? Our TA told us to write reactants first then products but that doesnt seem to match the solution manual
- Mon Feb 19, 2018 4:51 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Word equations
- Replies: 2
- Views: 489
Word equations
Will we be expected to write the whole cell reaction and use nerst equations for word equations? like without the elements and compounds explicitly written in their molecular formulas?
- Mon Feb 12, 2018 10:29 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Internal Energy State Function
- Replies: 2
- Views: 439
Re: Internal Energy State Function
Yes it is a state function because it does not matter the path that it takes to get to the final condition. Also remember delta S and delta H and delta G are state functions as well
- Mon Feb 12, 2018 10:25 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Monatomic and Diatomic
- Replies: 1
- Views: 345
Re: Monatomic and Diatomic
Our TA told us that we would be given a diatomic or monatomic obvious molecule, or if it is not obvious, it will be given explicitly in the question
- Mon Feb 12, 2018 10:24 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Midterm w18 -Last subject?
- Replies: 2
- Views: 486
Re: Midterm w18 -Last subject?
i think we mostly need to know just how K (and Q) relate to Gibbs free energy for the part of chapter 11 that we will be tested on
- Wed Feb 07, 2018 4:30 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2 [ENDORSED]
- Replies: 1
- Views: 214
Test 2 [ENDORSED]
Will the material covered on Test 2 be up until the 14th or the 16th of February?
- Tue Feb 06, 2018 11:32 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: W
- Replies: 3
- Views: 377
Re: W
it also helps to redraw the molecule as many times as you can by rearranging the element placements, almost like you would with a resonance structure, to show how many different states the molecule can have.
- Tue Feb 06, 2018 11:30 pm
- Forum: Van't Hoff Equation
- Topic: homework question 11.89
- Replies: 1
- Views: 405
homework question 11.89
How did they get the equation in 89 and how did they get the partial pressures out of 100? Im confused reading the solution manual for this problem.
- Tue Feb 06, 2018 11:25 pm
- Forum: Phase Changes & Related Calculations
- Topic: Environmental impact?
- Replies: 6
- Views: 1007
Environmental impact?
On Outline 1 on Lavelle's website, it states this as the last learning goal bullet: "Understand the environmental impact of burning fossil fuels, and the use of alternative
fuels". Will we have to know this even though Lavelle did not cover this in lecture?
fuels". Will we have to know this even though Lavelle did not cover this in lecture?
- Wed Jan 31, 2018 3:42 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: State functions [ENDORSED]
- Replies: 7
- Views: 744
State functions [ENDORSED]
Are the only state functions we've learned so far deltaH, detltaG, and deltaU? But the w and q are not state functions?
- Wed Jan 31, 2018 3:39 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem Community Posts
- Replies: 5
- Views: 851
Re: Chem Community Posts
My TA told us it is due 11:59 in Sundays
- Wed Jan 31, 2018 3:33 pm
- Forum: Phase Changes & Related Calculations
- Topic: Example in Lecture
- Replies: 4
- Views: 502
Re: Example in Lecture
If i understand correctly I think it is because when deltaG is 0, that is the system's boiling point, and when deltaG is negative, the reaction is favorable. So bromine would vaporize, or become a gas from a liquid, at any point equal to or above 333K because this is when Br2 has its boiling point
- Wed Jan 24, 2018 12:25 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Heat vs. Temp
- Replies: 9
- Views: 896
Re: Heat vs. Temp
you can also see this with the heating curves. for example, when ice is melted into liquid water, there is a plateau where there is heat being added but the temperature remains constant. this means molecules are transferring energy faster, but there is not a significant increase in the how fast the ...
- Wed Jan 24, 2018 12:17 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Released
- Replies: 3
- Views: 231
Re: Heat Released
i believe you would say the amount you found in positive, followed by the word released. for example, -55 kJ could be answered as 55 kJ released. hope that helps!
- Wed Jan 24, 2018 12:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 4
- Views: 434
Re: Bond Enthalpies
also, make sure to multiply the bonds by the number of moles for each reactant and each product!
- Wed Jan 17, 2018 10:01 am
- Forum: Phase Changes & Related Calculations
- Topic: Formula Sheet? [ENDORSED]
- Replies: 3
- Views: 379
Formula Sheet? [ENDORSED]
Will we have a formula sheet for this quiz? And will it be the same one as 14A or will it be different?
- Tue Jan 16, 2018 8:34 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: What does R stand for?
- Replies: 13
- Views: 3332
Re: What does R stand for?
R should also be given on the formula and constant sheet Lavelle gives us for the test
- Tue Jan 16, 2018 8:32 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimetry
- Replies: 2
- Views: 260
Re: Calorimetry
our TA also said if the c of the calorimeter is given in the problem you need to add it to q of Cu. Thus, the equation could be q of H2O = q of Cu + q of calorimeter
- Tue Jan 16, 2018 8:31 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Work function
- Replies: 4
- Views: 326
Re: Work function
i also think w is negative when the reaction is expansive and the delta V is positive, and 0 when the reaction takes place in a vacuum with free expansion.
- Thu Jan 11, 2018 8:20 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Chapter 8
- Replies: 6
- Views: 485
Chapter 8
where do the homework problems start since we are starting halfway through the chapter? Also what section in the book are we starting from within chapter 8?
- Thu Jan 11, 2018 8:16 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 6
- Views: 2320
Re: Bond Enthalpies
And vice versa, if you were to add bonds, the reaction would be exothermic because energy is released when bonds are formed. Thus it would be negative if you were talking about the opposite.
- Thu Jan 11, 2018 8:12 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: standard enthalpiy of formation
- Replies: 2
- Views: 128
standard enthalpiy of formation
What is the difference between standard enthalpies of formations of solutions and standard enthalpies of formations of gases?
- Mon Dec 04, 2017 12:47 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changing K but not changing K? [ENDORSED]
- Replies: 1
- Views: 145
Changing K but not changing K? [ENDORSED]
I understand that only temperature changes K and that adding more reactants or more products does not change the K, but how come when you do the reverse reaction (1/k) the K value changes?
- Mon Dec 04, 2017 12:44 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: strong acid/base?
- Replies: 3
- Views: 581
strong acid/base?
How can you tell it is a strong acid or strong base just by looking at the molecular formula?
- Tue Nov 28, 2017 5:15 pm
- Forum: Sigma & Pi Bonds
- Topic: When do Sigma and Pi bonds occur?
- Replies: 4
- Views: 710
Re: When do Sigma and Pi bonds occur?
when you have a single bond, it is a sigma bond. A double bond consists of a sigma and pi bond, one for each bond line. A triple bond consists of a sigma and 2 pi bonds, one for each bond line as well.
- Tue Nov 28, 2017 5:13 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination compounds and complexes
- Replies: 2
- Views: 262
Re: Coordination compounds and complexes
Also, the coordination sphere is referring to a central (metal) atom and its array of molecules or anions (ligands) around it. The coordination sphere consists of anything within the [ ] of the compound name.
- Mon Nov 20, 2017 1:50 pm
- Forum: Ideal Gases
- Topic: 11.3 [ENDORSED]
- Replies: 2
- Views: 385
Re: 11.3 [ENDORSED]
In lecture, Lavelle said that we should give the K constant based on what is given to us, so if pressures are given, use Kp and if concentrations are given, use Kc.
- Mon Nov 20, 2017 1:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homework Section [ENDORSED]
- Replies: 2
- Views: 292
Homework Section [ENDORSED]
What range of the homework problems on the syllabus should we do to only practice the 11.1 -11.8 material that will be on the next exam?
- Sat Nov 18, 2017 11:26 am
- Forum: Naming
- Topic: Naming Ligands
- Replies: 1
- Views: 247
Naming Ligands
Do we need to know all the common ligands listed in figure 17.4 for the next exam? Or just the ones discussed in lecture and the ones in our homework?
- Fri Nov 17, 2017 3:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Class Before Thanksgiving [ENDORSED]
- Replies: 2
- Views: 340
Class Before Thanksgiving [ENDORSED]
Hi, what sections in the book will the lecture on Wednesday 11/22 cover? I would like to review it on my own since my flight home is that Tuesday before.
- Wed Nov 15, 2017 5:40 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Understanding sigma and pi bonds?
- Replies: 8
- Views: 828
Re: Understanding sigma and pi bonds?
another thing to add is that sigma bonds can rotate and pi bonds cannot rotate. if pi bonds rotate, then they will break, causing a chemical reaction
- Wed Nov 15, 2017 5:38 pm
- Forum: Hybridization
- Topic: Polar/nonpolar [ENDORSED]
- Replies: 14
- Views: 2647
Re: Polar/nonpolar [ENDORSED]
can you always use the trick that Lavelle was saying where if water would want to bond on different locations of the molecule, then the molecule is polar for every compound?
- Wed Nov 08, 2017 9:18 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodes on the Midterm?
- Replies: 4
- Views: 598
Re: Nodes on the Midterm?
Hi, my TA told our discussion that we only need to know that S does not have any nodes but P does have a node, which is an area of zero electron density. He said that is all we need to know for this class.
- Wed Nov 08, 2017 9:17 pm
- Forum: Lewis Structures
- Topic: Polyatomic Ions
- Replies: 1
- Views: 171
Re: Polyatomic Ions
Hi, my TA told me that we will be given the polyatomic ion's molecular formula if we need to use them on the test!
- Tue Oct 31, 2017 11:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Review [ENDORSED]
- Replies: 4
- Views: 737
Re: Midterm Review [ENDORSED]
For the midterm, will we be expected to write the compounds/ions given the written name or will the molecular formula of compounds/ions be given to us? (I mean like will we be given just sulfate ion, or will be told that a sulfite ion is SO3^2-?)
- Mon Oct 30, 2017 1:04 pm
- Forum: Lewis Structures
- Topic: Homework Question 2.37B [ENDORSED]
- Replies: 2
- Views: 228
Re: Homework Question 2.37B [ENDORSED]
I think the shielding refers to the reduced affect of the nuclear charge, meaning when there are electrons in an inner shell, the outer shell electrons experience less than actual nuclear charge because electron repulsions work against the pull of the nucleus
- Mon Oct 30, 2017 1:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Review [ENDORSED]
- Replies: 4
- Views: 737
Midterm Review [ENDORSED]
Is there a website or place where I can look at previous midterm problems to prepare for our midterm next Thursday?
- Mon Oct 23, 2017 11:08 pm
- Forum: Trends in The Periodic Table
- Topic: Trends of ionic radius
- Replies: 4
- Views: 730
Re: Trends of ionic radius
Electrons make the atom bigger because they increase the number of shells the atom has. So losing electrons (becoming cation) would mean you are reducing the number of energy levels and therefore decreasing the size of the atom. Vice versa, since an anion is gaining electrons, it has more shells tha...
- Mon Oct 23, 2017 11:03 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 3
- Replies: 2
- Views: 327
Re: Test 3
It says on his website that the test will only cover to the end of chapter 1 and the entire chapter 2
- Wed Oct 18, 2017 5:07 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Precision and constants [ENDORSED]
- Replies: 2
- Views: 347
Re: Precision and constants [ENDORSED]
My TA told our discussion to use the exact number of sig figs given to you on Lavelle's formula sheet when solving problems with constant. He told our class not to round them, but rounding will not make a huge difference in your answer if you do every thing else correctly.
- Wed Oct 18, 2017 5:03 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: E-p distribution
- Replies: 2
- Views: 204
Re: E-p distribution
I think he meant electron density distribution but I'm not 100% sure
- Wed Oct 11, 2017 5:45 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Wavelengths of Electromagnetic Radiation
- Replies: 4
- Views: 2267
Re: Wavelengths of Electromagnetic Radiation
Haha it autocorrected mnemonic to pneumonic my bad
- Wed Oct 11, 2017 5:44 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Wavelengths of Electromagnetic Radiation
- Replies: 4
- Views: 2267
Re: Wavelengths of Electromagnetic Radiation
You can remember it by the pneumonic:
Raul's Mother is Visiting Uncle Xavier's Garden
Radio, Microwave, Infared, Visible, UV, X-ray, Gamma Ray
This follows the electromagnetic spectrum in order from decreasing wavelength (and increasing frequency).
Raul's Mother is Visiting Uncle Xavier's Garden
Radio, Microwave, Infared, Visible, UV, X-ray, Gamma Ray
This follows the electromagnetic spectrum in order from decreasing wavelength (and increasing frequency).
- Wed Oct 11, 2017 5:39 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Energy Level Series
- Replies: 2
- Views: 346
Re: Energy Level Series
The energy levels are discrete amounts of energy that the electron jumps to when it gets excited from that specific amount of energy. When the electron moves to a higher energy state, it becomes unstable, and emits the energy it just received to return back down to its stable ground state. The Balme...
- Wed Oct 04, 2017 11:02 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Amount of a stubstance
- Replies: 2
- Views: 394
Re: Amount of a stubstance
When a problem is asking for X amount of an element, and that element seems to often occur in a pair (e.g O vs O^2), if the problem doesn't specify, do you solve for the amount as the single element or in a pair? Or does it not matter? Hi, I think for these types of problems, if it is a common diat...
- Wed Oct 04, 2017 10:53 pm
- Forum: SI Units, Unit Conversions
- Topic: Sig Figs
- Replies: 12
- Views: 3246
Re: Sig Figs
I get confused with sig figs when there are zeros. For example, if the number is 0.020, is there 2 or 3 sig figs? This example would only have 2 sig figs because only the trailing zeros are significant if they are after a decimal point. Any leading zeros before a non-zero number is not significant,...