Search found 68 matches
- Sun Mar 17, 2019 10:24 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Bomb Calorimeter
- Replies: 5
- Views: 2450
Re: Bomb Calorimeter
I thought so because the pressure and volume is constant!
- Sat Mar 16, 2019 11:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K
- Replies: 3
- Views: 594
Re: K
K is the equilibrium constant so yes!
- Wed Mar 13, 2019 8:12 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: rate constants at equilibrium
- Replies: 2
- Views: 611
rate constants at equilibrium
When the reaction is at equilibrium, are the rate constants of the forward and reverse equal? In my discussion notes I have
K=1 so k=k' ?
K=1 so k=k' ?
- Mon Mar 11, 2019 6:13 pm
- Forum: Second Order Reactions
- Topic: error for 15.39 sixth edition
- Replies: 1
- Views: 232
error for 15.39 sixth edition
So the question asks to determine the time required for each reaction to take place. For part 1 it gives the reaction 2A ---> B + C. It also says these reactions are second order. If it is second order isn't the equation supposed to be 1/[A]t = 2kt + 1/[A]initial since there is a coefficient of 2 in...
- Sun Mar 10, 2019 10:09 pm
- Forum: First Order Reactions
- Topic: stoichiometry
- Replies: 2
- Views: 301
stoichiometry
How does stoichiometry come into kinetics? There are some questions in the book that ask about finding k constants when they give you the initial concentration of A but then give you a concentration of B at the some point in time?
- Sun Mar 10, 2019 9:32 pm
- Forum: Second Order Reactions
- Topic: negative in front of k
- Replies: 1
- Views: 248
negative in front of k
I dont understand what happens to the negative in front of k for integrated 2nd order rate laws??
- Sat Mar 09, 2019 9:09 pm
- Forum: General Rate Laws
- Topic: integrals
- Replies: 8
- Views: 991
integrals
can someone please explain integrals to me? I never took calculus or ap calculus and I am super confused? Why does ln come in?
- Tue Mar 05, 2019 10:09 am
- Forum: General Rate Laws
- Topic: Order Reaction/Rate Law
- Replies: 3
- Views: 444
Re: Order Reaction/Rate Law
I think you use the rate law to find m and n which represent the order of the reactant.
- Tue Mar 05, 2019 10:07 am
- Forum: General Rate Laws
- Topic: rate and dependence on [R]
- Replies: 2
- Views: 287
Re: rate and dependence on [R]
I think so since the initial concentrations are the reactant concentrations
- Tue Mar 05, 2019 10:06 am
- Forum: General Rate Laws
- Topic: K and k [ENDORSED]
- Replies: 2
- Views: 336
K and k [ENDORSED]
What is the difference between capital K and lowercase k??
- Tue Feb 26, 2019 12:10 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagram help.
- Replies: 2
- Views: 303
Re: Cell diagram help.
You add an inert metal when the ions of the same element are in the same solution or when you have a gas and ion in the same solution
- Mon Feb 25, 2019 6:03 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6th edition 14.31
- Replies: 1
- Views: 211
6th edition 14.31
In the solutions manual for part d it says NO3- is the oxidizing agent and it is in the cathode, but how is this possible if it goes from NO3- to No2. Is it not losing an electron, therefore it is oxidizing so it is part of the anode??
- Mon Feb 25, 2019 4:26 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: reversing reaction [ENDORSED]
- Replies: 3
- Views: 403
reversing reaction [ENDORSED]
how come for some of the homework problems in the solutions manual they reverse the reaction. What is the significance of this?
- Tue Feb 19, 2019 10:31 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: O2
- Replies: 5
- Views: 523
Re: O2
O2 is a naturally occurring compound.
- Wed Feb 13, 2019 10:51 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: delta S
- Replies: 7
- Views: 767
delta S
under what conditions does delta S = 0
- Wed Feb 13, 2019 10:07 am
- Forum: Calculating Work of Expansion
- Topic: Hotdog Midterm #6
- Replies: 2
- Views: 378
Hotdog Midterm #6
If you start at 100 L and end at 100 L then volume for the entire process is unchanging so if delta V is equal to 0 doesnt work = 0??
- Wed Feb 13, 2019 12:54 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isothermal and reversible
- Replies: 2
- Views: 378
Re: Isothermal and reversible
One of the TA's in the review session said it is possible to have a irreversible isothermal expansion but we do not need to worry about in this class.
- Tue Feb 12, 2019 10:36 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: clarification
- Replies: 1
- Views: 280
clarification
To clarify, when the reaction is reversible delta S is 0?
- Tue Feb 12, 2019 11:46 am
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 24136
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Can someone explain how to do #1. I found the heat gained by the water but without the final temperature of the metal how would I find the specific heat??
- Tue Feb 12, 2019 10:30 am
- Forum: Administrative Questions and Class Announcements
- Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
- Replies: 49
- Views: 11732
Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
Mya Majewski 1L wrote:For #6, how did we get w=9.119 x 10^3 J?
For the first part it says you preform an isobaric compression to 10L. Isobaric is constant pressure so work is equal to -PdV. So pressure is 1.00 atm and the change of V is 10-100 so -90. This comes to -90 L.atm you then convert this to Joules
- Sun Feb 10, 2019 10:26 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity
- Replies: 4
- Views: 428
Re: Heat Capacity
Yes it just depends what units you are working with!
- Sun Feb 10, 2019 10:25 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Occupying positions
- Replies: 2
- Views: 349
Re: Occupying positions
In a solid the molecules are not as free to move around as in a liquid, because in a solid molecules are more tightly packed so they occupy less positions
- Wed Feb 06, 2019 5:48 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 6th edition 6.41
- Replies: 1
- Views: 212
6th edition 6.41
In the solutions manual they add the reaction enthalpy of fusion to the equation q=mCdeltaT when calculating heat of the ice cube. Can someone please explain why this is done?
- Sun Feb 03, 2019 5:38 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: HW
- Replies: 3
- Views: 384
Re: HW
I think you can still do hw on thermochemistry since we recently started to cover thermodynamics.
- Sat Feb 02, 2019 9:28 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: delta H vs q
- Replies: 9
- Views: 937
Re: delta H vs q
delta H is change in enthalpy and q is heat added to the system
- Sat Feb 02, 2019 9:25 pm
- Forum: Calculating Work of Expansion
- Topic: Calculus in Chem
- Replies: 1
- Views: 235
Calculus in Chem
Hi! I never took calculus in high school let alone AP calculus. Can someone explain to me why we need integrals? I know Professor Lavelle answered this question in class but I didn't get the answer. Thank you!
- Thu Jan 24, 2019 11:23 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acid/ Base
- Replies: 1
- Views: 200
Re: Acid/ Base
Ka is the constant relating to acids and its dissociation while Kb is the concentration related to bases and their ionization
- Thu Jan 24, 2019 11:21 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pKa vs. pH
- Replies: 15
- Views: 3017
Re: pKa vs. pH
pKa is a the -log of the acid dissociation constant, it is a measure of acid strength. pH is a measure of the concentration of H+ ions.
- Thu Jan 24, 2019 11:19 am
- Forum: Phase Changes & Related Calculations
- Topic: outline 3
- Replies: 1
- Views: 236
outline 3
Will next weeks homework be on textbook questions from outline 3?
- Sun Jan 20, 2019 11:49 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Error in Solutions manual [ENDORSED]
- Replies: 1
- Views: 1019
Error in Solutions manual [ENDORSED]
I have the 6th edition and for 12.35, it says list the acids in order of increasing strength, and it says the larger the Ka value, the stronger the acid, yet the list of acids is in the wrong order and it should be the other way around. Is this an error or am I thinking about this wrong?
- Sat Jan 19, 2019 6:12 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chateliers Principle
- Replies: 4
- Views: 387
Le Chateliers Principle
How does the affect of temperature and pressure differ when it comes to changing the equilibrium?
- Sat Jan 19, 2019 6:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Post Assessment Part 2
- Replies: 1
- Views: 149
Post Assessment Part 2
There is a question in this post assessment asking about finding the equilibrium constant of reaction 2BrCI <-> Br2 + Cl2. The question says something about 18.3% of the BrCI gas remains at equilibrium. However, no matter how many times I attempt the question I cant get the answer. Can someone expla...
- Fri Jan 11, 2019 11:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Problem 11.7
- Replies: 2
- Views: 141
Re: Problem 11.7
The flasks are in order of time. So to get the answer you just count the amount of diatomic molecules present in each flask. And if you do this you will notice both flask 3 and 4 both have 5 diatomic molecules. So the reaction reached equilibrium at flask 3 because that is where the reactants stay c...
- Fri Jan 11, 2019 11:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ice table
- Replies: 4
- Views: 459
ice table
Today in lecture, professor Lavelle gave an example with the reaction PCI5, PCI3, and CI2. When he made the ICE table he made the change in concentration +x. How do we know to put +x? Can someone please explain, thank you!
- Wed Jan 09, 2019 4:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: finding K Value
- Replies: 3
- Views: 219
finding K Value
In some questions they ask to find the K value from reactions where the coefficients were either divided or multiplied by a certain number, such a 2. How come when you multiply by 2, you have to square the given K value, and when you divide by 2, you square root the given K value?
- Fri Dec 07, 2018 10:03 pm
- Forum: Bronsted Acids & Bases
- Topic: strong acid
- Replies: 2
- Views: 314
strong acid
I am still confused on how to tell if an acid is strong or not. Does electronegativity play a role in acid strength??
- Tue Dec 04, 2018 11:06 am
- Forum: Amphoteric Compounds
- Topic: amphoteric substances
- Replies: 3
- Views: 419
amphoteric substances
How can you tell a substance is amphoteric by just looking at it? or is there a way you can figure it out?
- Thu Nov 29, 2018 7:33 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape
- Replies: 2
- Views: 305
Re: Molecular Shape
I dont think there will be a chart provided since Dr Lavelle said you are expected to memorize the bond angles and shape names. Try memorizing the formulas for molecular shape (e.g AX3E, which correpsonds to trigonal pyramid)
- Thu Nov 29, 2018 7:30 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Resonancy and VSEPR
- Replies: 1
- Views: 158
Re: Resonancy and VSEPR
Resonancy is not totally important when it comes to molecular shape because it does not matter which lewis structure you consider. Since all of the resonance structures will have the same shape it doesnt matter which one you focus on since single and multiple bonds are counted as one bond
- Thu Nov 29, 2018 7:26 am
- Forum: Naming
- Topic: coordination compound
- Replies: 1
- Views: 186
coordination compound
So within a coordination compound, are the ligands always going to be lewis bases, and the central atom or ion is the lewis acid or can it be switched around??
- Sun Nov 18, 2018 9:58 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: polarizing power and polarizability
- Replies: 2
- Views: 322
polarizing power and polarizability
Is it safe to say that polarizing power is indirectly proportional to atomic radius and directly proportional to electronegativity? and is polarizability indirectly proportional to electronegativity and directly proportional to atomic radius??
- Sat Nov 17, 2018 7:54 pm
- Forum: Bond Lengths & Energies
- Topic: 6th edition 3.87
- Replies: 2
- Views: 338
6th edition 3.87
can someone please explain this question to me I don't get it at all
- Thu Nov 15, 2018 11:38 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Arrangement vs Shape
- Replies: 3
- Views: 406
Arrangement vs Shape
Can someone please clarify what the difference is when asked for arrangement vs when asked for molecular shape? I know it has something to do with the lone pairs but im not entirely sure
- Mon Nov 12, 2018 1:48 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Cations and polarizing power
- Replies: 2
- Views: 320
Re: Cations and polarizing power
Higher polarizing power refers to "atoms and ions that CAN cause large distortions." I capitalized "can" because that word made me understand what is meant by polarizing power. So basically the higher poloarizing power an atom has, the more it can pull electrons toward it. Small,...
- Mon Nov 12, 2018 1:44 pm
- Forum: Electronegativity
- Topic: Ionic Character
- Replies: 2
- Views: 151
Re: Ionic Character
As you go down a group, atomic radius increases, so there is less pulling power on the electrons. CO2 is more ionic because oxygen is in the second period so its atomic radius is small which means there is more pulling on the elctrons by the nucleus. Therefore, Oxygen is very high in electronegtivit...
- Mon Nov 12, 2018 1:39 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: 3.39b 6th edition
- Replies: 2
- Views: 364
Re: 3.39b 6th edition
Potassium and Phosphorus have a high difference in electronegativity so they have more ionic so they are not covalently bonded so the Potassium atoms are separate.
- Sat Nov 03, 2018 12:09 am
- Forum: Empirical & Molecular Formulas
- Topic: Mass Composition
- Replies: 3
- Views: 399
Mass Composition
Okay so there are many questions that give you the mass composition of each element in a compound and ask to find the empirical or molecular formula. The percentage of each element adds up to a 100%. What if they did not add up to 100%, how we would go about solving the problem??
- Fri Nov 02, 2018 11:40 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Electrons in Orbitals
- Replies: 2
- Views: 343
Re: Electrons in Orbitals
For example when n=3 and l=2 we know this corresponds to 3d. Since l is equal 2 we know the values for ml can be: -2,-1,0,1,2. This tells us how many orbitals there are. In this case it is 5 orbitals. Since there are 2 electrons in each orbital, there are 10 electrons
- Mon Oct 29, 2018 11:26 pm
- Forum: Ionic & Covalent Bonds
- Topic: 6th edition 3.9 and 3.11
- Replies: 1
- Views: 159
6th edition 3.9 and 3.11
Can someone please explain the answers to these two questions. I do not understand them at all. Thank you in advance!
- Mon Oct 29, 2018 12:21 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: 2.25 6th Edition
- Replies: 2
- Views: 395
Re: 2.25 6th Edition
For this question you just take the number of orbitals and multiply by 2 to get the number of electrons that can occupy that specific orbital. So for example the 4p orbital corresponds to the angular momentum quantum number 1. This number can have 3 values of the magnetic quantum number -1,0,1. Thsi...
- Mon Oct 29, 2018 12:14 am
- Forum: Properties of Light
- Topic: Photoelectric Effect
- Replies: 7
- Views: 937
Re: Photoelectric Effect
Intensity is what effects the amount of electrons. So as intensity increases, quantity of electrons being removed increases
- Sun Oct 21, 2018 5:39 pm
- Forum: Einstein Equation
- Topic: HW Problem 1.25 (6th Edition)
- Replies: 2
- Views: 360
Re: HW Problem 1.25 (6th Edition)
For part b, convert 5.00 mg to g. Then using the equation m=nM, find n, which is amount in moles. Then use the equation N=nNa to find N, which is number of sodium atoms. Use the answer from part a and multiple that number by the number of sodium atoms. For part c, just divide the answer from part a ...
- Sun Oct 21, 2018 5:34 pm
- Forum: Einstein Equation
- Topic: Chapter 1 Question 27
- Replies: 2
- Views: 525
Re: Chapter 1 Question 27
First convert 420 nm to m. Then solve for the energy per photon by using the equation E=hc/(wavelength). Once you have that answer, you can divide the total energy which is 64J (1 W= 1 J.s, so 32 x 2=64 J) and divide that by the energy per photon. This will get you the amount in photons. To solve fo...
- Sun Oct 21, 2018 2:00 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: 6th edition 2.1
- Replies: 1
- Views: 164
Re: 6th edition 2.1
When the electron in a hydrogen atom makes a transition from the 1s orbital to a 2p orbital the atom's radius is increasing because the number of enegry levels is increasing, and so is the number of electrons. Each energy level is getting farther from the nucleus. So when a electron moves from 1s, w...
- Sat Oct 20, 2018 10:00 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: test 2 topics
- Replies: 3
- Views: 458
test 2 topics
This was probably already asked, but will electron configurations be on test 2? For example, will we need to know the ground state electron configuration of an element??
- Fri Oct 19, 2018 12:20 am
- Forum: *Shrodinger Equation
- Topic: Orbitals, Lobes, e- density
- Replies: 3
- Views: 636
Orbitals, Lobes, e- density
The last time I took chemistry was 10th grade, so I am a little lost on the whole orbital concept and the wave function. Can someone give me a simple explanation? If you can me it as simple as possible that would be great.
- Sun Oct 14, 2018 6:51 pm
- Forum: Properties of Electrons
- Topic: Energy Level Question
- Replies: 4
- Views: 378
Re: Energy Level Question
When an electron jumps from a lower energy level to a higher energy level (ex. n=1 to n=3) then energy is absorbed. Therefore, the electron gains energy since it is moving away from the nucleus. When an electron goes down to a lower energy level (returning to ground state) it emits energy. Therefore...
- Sun Oct 14, 2018 6:45 pm
- Forum: Properties of Light
- Topic: wavelengths and energy of a photon
- Replies: 2
- Views: 394
Re: wavelengths and energy of a photon
When the size of the wavelength increases (more far apart) then frequency decreases and I believe this causes energy to decrease. If the wavelength decreases(less space in between), then frequency increases therefore energy increases, specifically electromagnetic radiation. I found this on wikipedia...
- Sun Oct 14, 2018 6:39 pm
- Forum: Properties of Light
- Topic: Test 2
- Replies: 17
- Views: 1330
Test 2
Does anyone know if test 2 will cover both chapter 1 and 2 of the textbook or just chapter 1?
- Mon Oct 08, 2018 11:03 pm
- Forum: Limiting Reactant Calculations
- Topic: Test 1
- Replies: 2
- Views: 363
Re: Test 1
Hi Katherine! First tests are always scary because it's hard to know what to expect, but just be confident and don't worry too much! My UA session is Tuesday 6-8pm and I go over practice test questions that are based off of previous exam questions, so that could be helpful. Doing problems is always...
- Mon Oct 08, 2018 11:02 pm
- Forum: Limiting Reactant Calculations
- Topic: How to find the limiting reactant easily and quickly
- Replies: 5
- Views: 13824
Re: How to find the limiting reactant easily and quickly
Okay first balance the equation given if it is not already. Then if given the mass of the two reactants convert both to moles. Then divide each of those amounts by the number of moles in the equation. For example 2Al+6HCI --> 2AlCI3 + 3H2 If given the grams of Al and HCI you convert to moles. In thi...
- Mon Oct 08, 2018 9:25 pm
- Forum: Limiting Reactant Calculations
- Topic: Test 1
- Replies: 2
- Views: 363
Test 1
I am really nervous about Test 1, and I have done all the homework problems about 4 times. Is there anything else I can study? Or what is the most difficult topic for students to comprehend or a topic students have the most questions on?
- Mon Oct 08, 2018 10:05 am
- Forum: Empirical & Molecular Formulas
- Topic: Converting Units
- Replies: 5
- Views: 532
Re: Converting Units
For me personally, it is much easier to convert all units to the correct units in the beginning instead of at the end. I don't know if that is the best way but it has worked for me!
- Sat Oct 06, 2018 10:32 am
- Forum: Limiting Reactant Calculations
- Topic: Finding Limiting Reactants
- Replies: 3
- Views: 301
Finding Limiting Reactants
Is the limiting reactant always going to be the one with the least moles? or do you have to take into account the molar ratio? and if you do take into account the molar ratio how would you work that into finding the limiting reactant??
- Fri Oct 05, 2018 11:40 pm
- Forum: Properties of Light
- Topic: Classical vs Quantum
- Replies: 2
- Views: 355
Classical vs Quantum
Can someone please explain the difference between classical mechanics vs quantum mechanics because I was totally lost in lecture about the whole pouring water from a flowering can example??
- Wed Oct 03, 2018 11:36 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Question E 15
- Replies: 2
- Views: 166
Re: Question E 15
When you subtract the molar mass of the metal of the two hydroxide atoms from the molar mass of the metal hydroxide, you get a molar mass of 40.084. And the metal matching this molar mass is calcium (40.078) so now you take find the molar mass of calcium sulfide!
- Tue Oct 02, 2018 3:51 pm
- Forum: Empirical & Molecular Formulas
- Topic: problem F13
- Replies: 3
- Views: 386
problem F13
Problem F13 in the textbook asks "In an experiment, 4.14g of phosphorus combined with chlorine to produce 27.8g of a white solid compound. What is the empirical formula of the compound? In the solutions manual it skips the step of finding mass percentage of each element. So instead of dividing ...
- Tue Oct 02, 2018 3:10 pm
- Forum: Significant Figures
- Topic: Significant Figures
- Replies: 6
- Views: 813
Significant Figures
Can someone explain addition and subtraction with significant figures? We went over it in discussion today but I was still confused about how many significant figures should be in the final answer?