Search found 64 matches
- Tue Mar 12, 2019 11:07 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Electrolysis
- Replies: 2
- Views: 804
Re: Electrolysis
I don't know exactly what specifically we will have to know for electrolysis for the final, but electrolysis is when an electron current is used to drive a nonspontaneous redox reaction (electrical energy -> chemical energy).
- Tue Mar 12, 2019 10:59 pm
- Forum: General Science Questions
- Topic: Organic Molec Naming?
- Replies: 2
- Views: 527
Re: Organic Molec Naming?
We never went over organic molecules and naming in lecture, so I do not think that they will be on the final.
- Thu Mar 07, 2019 10:01 pm
- Forum: Second Order Reactions
- Topic: Half life of a second order reaction
- Replies: 1
- Views: 272
Re: Half life of a second order reaction
Yes, t½ = 1 / k [A]o
- Thu Mar 07, 2019 9:58 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Test 2
- Replies: 4
- Views: 508
Re: Test 2
Rusting is spontaneous because it naturally occurs without any outside intervention even though it happens over a long period of time.
- Thu Mar 07, 2019 9:51 pm
- Forum: Balancing Redox Reactions
- Topic: Test #2
- Replies: 6
- Views: 777
Re: Test #2
Samantha Silva 1F wrote:Does anyone know if the TA's passed back the tests? I was unable to attend.
Yes, the TAs passed back the tests during our discussion sections this week.
- Thu Mar 07, 2019 9:38 pm
- Forum: General Science Questions
- Topic: Final
- Replies: 7
- Views: 1189
Re: Final
I don't think he does.
- Thu Mar 07, 2019 9:15 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox Reactions
- Replies: 5
- Views: 705
Re: Balancing Redox Reactions
1. Write the two unbalanced equations for the oxidation and reduction half-reactions 2. Balance all the elements in the half-reactions except O and H 3. In a basic solution, balance O by using H2O; then balance H by adding H2O to the side of each half reaction that needs H and adding OH- to the othe...
- Thu Mar 07, 2019 5:54 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Calculating Eºcell
- Replies: 2
- Views: 556
Re: Calculating Eºcell
When using the equation, Eºcell = Eºcathode - Eºanode, you do not need to flip the sign for the standard reduction potential of the anode.
- Wed Mar 06, 2019 11:56 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 7th edition 6N.1(b)
- Replies: 1
- Views: 251
Re: 7th edition 6N.1(b)
I noticed that too and I think it is an error in the solutions manual.
- Sun Mar 03, 2019 11:04 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 7th Edition 6N.3c
- Replies: 2
- Views: 314
7th Edition 6N.3c
For Q in the solutions manual, the partial pressures are in the numerator and the concentrations are in the denominator. Are you allowed to mix partial pressures and concentrations when calculating Q?
- Tue Feb 26, 2019 9:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 22844
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Can someone please explain #4 on the Gibbs Free Energy worksheet?
- Mon Feb 25, 2019 2:25 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Tips for Discussion Test
- Replies: 6
- Views: 548
Re: Tips for Discussion Test
I find the outlines on his website to be useful guidelines on the main topics we need to know for the tests. Test 2 covers Gibbs free energy and electrochemistry up to the Nernst equation. Homework problems are also very good practice for the types of questions that could be asked on the tests.
- Mon Feb 25, 2019 2:15 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Stability of reactants and products Midterm question
- Replies: 3
- Views: 650
Re: Stability of reactants and products Midterm question
The correct response would be that the equilibrium constant is large (K = 3*10^4), therefore, the product (SO3) is more stable.
- Sun Feb 17, 2019 1:32 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: reversible and irreversible processes
- Replies: 9
- Views: 1474
Re: reversible and irreversible processes
Also, the work calculated for an irreversible expansion is w= -P∆V while the work calculated for a reversible expansion is w= -nRTln(V2/V1).
- Sun Feb 17, 2019 1:20 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: state functions and properties
- Replies: 11
- Views: 5932
Re: state functions and properties
A state function is a property that depends only on the current state of the system and is independent of how the state was prepared.
- Sun Feb 17, 2019 1:17 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: calculating delta S
- Replies: 4
- Views: 442
Re: calculating delta S
Boyle's Law states that P1V1=P2V2 and by rearranging the equation, you are left with V2/V1 = P1/P2.
- Sun Feb 17, 2019 1:12 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: constant C
- Replies: 7
- Views: 1005
Re: constant C
C is the general term for specific heat. Cv is specific heat at constant volume. Cp is specific heat at constant pressure.
- Sat Feb 09, 2019 8:35 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: 7th edition 4E.5
- Replies: 3
- Views: 430
Re: 7th edition 4E.5
The C-H bonds of the 3C2H2 are never broken. Therefore, the C-H bonds do not need to be formed again to make C6H6.
- Wed Feb 06, 2019 10:50 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 7th Edition 4.15
- Replies: 2
- Views: 474
7th Edition 4.15
Hydrochloric acid oxidizes zinc metal in a reaction that produces hydrogen gas and chloride ions. A piece of zinc metal of mass 8.5 g is dropped into an apparatus containing 800.0 mL of 0.500 M HCl(aq). If the initial temperature of the hydrochloric acid solution is 25°C, what is the final temperatu...
- Wed Feb 06, 2019 8:45 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 7th Edition 4D.23
- Replies: 1
- Views: 238
7th Edition 4D.23
Calculate the standard enthalpy of formation of dinitrogen pentoxide from the following data:
2NO(g) + O2(g) -> 2NO2(g) ∆H° = -112.1 kJ
4NO2(g) + O2(g) -> 2N2O5(g) ∆H° = -110.2 kJ
Also, the standard enthalpy of NO = +90.25 kJ
How would you solve this?
2NO(g) + O2(g) -> 2NO2(g) ∆H° = -112.1 kJ
4NO2(g) + O2(g) -> 2N2O5(g) ∆H° = -110.2 kJ
Also, the standard enthalpy of NO = +90.25 kJ
How would you solve this?
- Sun Feb 03, 2019 1:19 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Function
- Replies: 10
- Views: 823
Re: State Function
A state function is a property whose value does not depend on the path taken to go from the initial to the final state(Ex: enthalpy). Work is not a state function because work is quantified based on the pathway it takes.
- Sat Feb 02, 2019 3:45 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Seventh edition ? 4C.13
- Replies: 1
- Views: 245
Re: Seventh edition ? 4C.13
The heat gained by the water in the ice cube is equal to the heat lost by the initial hot water in the glass. Therefore, use the heat formula for the water in the ice cube and the water in the glass and set them equal to each other to find final temp. You also need to be aware that the enthalpy chan...
- Sat Feb 02, 2019 3:15 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat Curve
- Replies: 6
- Views: 593
Re: Heat Curve
We will probably have to know the heat curve and the general concepts that it is indicating. I think it would also be helpful to know the key temperatures where a phase change is occurring in water (0 degrees Celsius and 100 degrees Celsius).
- Tue Jan 22, 2019 9:05 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 7th edition 5J.5 part b
- Replies: 3
- Views: 382
Re: 7th edition 5J.5 part b
You have to compare the number of moles of gas (don't include the solid).
- Mon Jan 21, 2019 10:28 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 22844
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Can someone please indicate the main steps to solve worksheet 1 problem #5?
- Mon Jan 21, 2019 6:21 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 7th Edition 6B.9
- Replies: 2
- Views: 253
Re: 7th Edition 6B.9
So then would the pOH of the solution be above 14?
- Mon Jan 21, 2019 6:02 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 7th Edition 6B.9
- Replies: 2
- Views: 253
7th Edition 6B.9
Is it possible to have a negative pH value? It is given that [H3O+] = 1.50 mol*L^-1, but the -log(1.50) = -.176
- Wed Jan 16, 2019 10:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Endothermic Reaction
- Replies: 4
- Views: 328
Re: Endothermic Reaction
If a reaction is endothermic, then heat is absorbed in the reaction. So if there is an increase in the temperature, the reaction will shift towards the products. If there is an increase in products, then the Kc value will increase.
- Wed Jan 16, 2019 9:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH
- Replies: 5
- Views: 352
Re: pH
The pH of a solution is the -log of the hydronium ion concentration: pH = -log[H3O+]
- Wed Jan 16, 2019 2:07 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: 5% approximation for weak acids/bases
- Replies: 2
- Views: 267
Re: 5% approximation for weak acids/bases
Lavelle said that if the K value is less than 10^-3, then typically we can use the approximation.
- Fri Jan 11, 2019 9:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentration of P using the Quadratic Formula
- Replies: 2
- Views: 146
Re: Concentration of P using the Quadratic Formula
I think he was talking about how you can plug in 1.59 for x in the equation x^2 + 1.80x - 5.40 and that equals zero.
- Fri Jan 11, 2019 9:26 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Changing Pressure
- Replies: 6
- Views: 526
Re: Changing Pressure
Decreasing the volume of a contained gas will increase its pressure, and increasing its volume will decrease its pressure.
- Fri Jan 11, 2019 12:20 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 7th Edition 5H.3
- Replies: 3
- Views: 899
Re: 7th Edition 5H.3
Using table 5G.2, you will notice that K=377 for 2BrCl(g) <-> Br2(g) + Cl2(g) at 300K and K=4.0*10^31 for H2(g) + Cl2(g) <-> HCl(g) at 300K. You are then able to multiple these 2 K values together in order to get the K value of the combined reaction.
- Tue Dec 04, 2018 8:03 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Identifying the Different Types of Acidic and Bases
- Replies: 2
- Views: 145
Re: Identifying the Different Types of Acidic and Bases
Bronsted acids donate protons and Bronsted bases accept protons. Lewis acids accept electrons and Lewis bases donate electrons. I would think that there are not anymore we need to know.
- Sun Dec 02, 2018 9:47 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: 7th Edition Focus 9C.5b [ENDORSED]
- Replies: 2
- Views: 300
7th Edition Focus 9C.5b [ENDORSED]
Can someone explain why CO3^2- serves as a monodentate or bidentate?
- Fri Nov 30, 2018 11:51 pm
- Forum: Sigma & Pi Bonds
- Topic: Strength of Sigma and Pi Bonds
- Replies: 5
- Views: 1083
Re: Strength of Sigma and Pi Bonds
It has to do with the orientation of overlapped orbitals. Sigma bonds are formed by end-to-end overlapping while pi bonds are formed by lateral overlapping. The extent of overlapping is maximized in sigma bonds and is therefore stronger than pi bonds.
- Fri Nov 30, 2018 11:42 pm
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 4
- Views: 622
Re: Resonance
Check the formal charges of the atoms when determining the most stable structure. Typically, the structure with the most formal charges of zero on atoms is the more stable Lewis structure. When there must be positive or negative formal charges on various atoms, the most stable structures generally h...
- Fri Nov 30, 2018 9:10 pm
- Forum: Lewis Acids & Bases
- Topic: Differentiating Between Lewis and Bronsted
- Replies: 2
- Views: 314
Re: Differentiating Between Lewis and Bronsted
Bronsted acids donate protons and Bronsted bases accept protons. Lewis acids accept electrons and Lewis bases donate electrons.
- Tue Nov 27, 2018 8:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Exam
- Replies: 3
- Views: 377
Re: Exam
It's the end of chemical bonding and all of molecular shape and structure.
- Sun Nov 25, 2018 2:13 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape
- Replies: 7
- Views: 685
- Sun Nov 25, 2018 2:10 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape
- Replies: 7
- Views: 685
Re: Molecular Shape
A seesaw structure occurs when the electron geometry is trigonal bipyramidal and there are 4 bonds to the central atom and 1 lone pair to the central atom.
- Sun Nov 25, 2018 1:54 am
- Forum: Octet Exceptions
- Topic: Exceptions
- Replies: 3
- Views: 565
Re: Exceptions
Group 13 elements are often exceptions to the octet rule. Since these atoms need to gain 5 electrons to fulfill their octet rule, the octet rule is not reliable in Group 13. Furthermore, elements in Period 3 or later have an expanded valence shell by using their empty d orbital to hold additional el...
- Sun Nov 25, 2018 1:40 am
- Forum: Hybridization
- Topic: pi and sigma bonds
- Replies: 3
- Views: 287
Re: pi and sigma bonds
A sigma bond is the same in all directions around the long axis of the bond with no nodal planes containing the internuclear axis. A pi bond has a single nodal plane containing the internuclear axis.
- Sun Nov 18, 2018 9:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Trigonal Bipyramidal
- Replies: 3
- Views: 396
- Sun Nov 18, 2018 9:42 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Octahedral to Square Planar
- Replies: 7
- Views: 920
Re: Octahedral to Square Planar
An octahedral shape occurs when there are six atoms symmetrically arranged around a central atom. A square planar shape occurs when two of these atoms are replaced by two lone pairs that are on opposite sites of the central atom, leaving a square planar shape.
- Sun Nov 18, 2018 9:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T Shaped
- Replies: 3
- Views: 550
Re: T Shaped
A T-shaped molecule occurs when there are 3 bonds and 2 lone pairs around the central atom in a molecule. The atoms bonded to the central atom have 90 degree angles between them to form a T-shape. The t-shaped geometry is related to the trigonal bipyramidal geometry, but two lone pairs occupy two po...
- Sat Nov 10, 2018 11:54 pm
- Forum: Electronegativity
- Topic: Electronegativity and Electron Affinity
- Replies: 4
- Views: 477
Re: Electronegativity and Electron Affinity
Electronegativity is the ability of a neutral atom to attract electrons towards itself. Electron affinity is the energy released when an electron is added to a neutral atom.
- Sat Nov 10, 2018 11:38 pm
- Forum: Bond Lengths & Energies
- Topic: VSEPR Model
- Replies: 1
- Views: 179
Re: VSEPR Model
The bond electron pair lies further from the atom than the lone pair of an atom (the lone pair is closer to the positively charged nucleus). Therefore, the lone pairs are closer to one another to make a greater repulsion between them.
- Sat Nov 10, 2018 11:22 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: molecular shape
- Replies: 3
- Views: 365
Re: molecular shape
I think that the only molecular shapes that we have to know are the ones we discuss in lectures.
- Sat Nov 03, 2018 2:24 pm
- Forum: Lewis Structures
- Topic: Lewis Base & Acid
- Replies: 2
- Views: 242
Re: Lewis Base & Acid
Lewis bases donate pairs of electrons (not protons) and Lewis acids accept pairs of electrons.
- Sat Nov 03, 2018 2:19 pm
- Forum: Student Social/Study Group
- Topic: Orbitals
- Replies: 2
- Views: 249
Re: Orbitals
I think of the ml as the integers ranging from -l to +l.
- Sat Nov 03, 2018 2:16 pm
- Forum: Student Social/Study Group
- Topic: Studying
- Replies: 7
- Views: 875
Re: Studying
I'm going to the as many review sessions as possible, look over all of my notes, and do as many homework problems as possible.
- Wed Oct 24, 2018 12:03 am
- Forum: *Particle in a Box
- Topic: Energy of shells vs. subshells
- Replies: 2
- Views: 892
Re: Energy of shells vs. subshells
I believe that s- electrons have a lower energy than p- electrons within the same shell.
- Tue Oct 23, 2018 11:56 pm
- Forum: Properties of Light
- Topic: Electromagnetic Spectrum
- Replies: 5
- Views: 631
Re: Electromagnetic Spectrum
I'm not sure whether or not we need to know it, but I think knowing it wouldn't hurt you. Going from shorter wavelength to longer wavelength, it is
gamma ray, x-ray, ultraviolet, visible, infrared, microwave, radio
gamma ray, x-ray, ultraviolet, visible, infrared, microwave, radio
- Mon Oct 22, 2018 8:08 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Quantum World Worksheet #7
- Replies: 2
- Views: 366
Quantum World Worksheet #7
An excited hydrogen atom emits light with a frequency of 1.14*10^14 Hz to reach the energy level for which n=4. In what principle quantum level did the electron begin? I made n2=4 in the equation and solved for n1 but I don't get 6 as the answer. Can someone show me the work for this problem using t...
- Sun Oct 21, 2018 2:21 am
- Forum: Photoelectric Effect
- Topic: spectral lines
- Replies: 6
- Views: 603
Re: spectral lines
Depending on what is given, it can be used to determine the frequency, wavelength, or the other energy level. I don't know for sure whether or not it will be on the 2nd test, but I think it is likely that it will be.
- Sun Oct 21, 2018 2:18 am
- Forum: Photoelectric Effect
- Topic: spectral lines
- Replies: 6
- Views: 603
Re: spectral lines
Also, I think that the Rydberg constant can be written in Hz or m^-1 depending on which formula you want to use.
- Sun Oct 21, 2018 2:05 am
- Forum: Photoelectric Effect
- Topic: spectral lines
- Replies: 6
- Views: 603
Re: spectral lines
I've seen the equation written both ways too and I think that both are correct. This formula is mainly used to determine the wavelength of light emitted by an electron moving between the energy levels of an atom.
- Sat Oct 13, 2018 7:01 pm
- Forum: Properties of Light
- Topic: E=hv
- Replies: 13
- Views: 1028
Re: E=hv
E stands for energy per photon.
- Sat Oct 13, 2018 6:59 pm
- Forum: Properties of Light
- Topic: Relationship with Equations
- Replies: 2
- Views: 184
Re: Relationship with Equations
E=hv indicates that the energy per photon is equal to Planck's constant times frequency. c=λv indicates that the speed of light is equal to the wavelength times the frequency. A possible relationship between the two equations is that you are able to solve for frequency in both and substitute it with...
- Tue Oct 09, 2018 2:41 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: E29 Part D
- Replies: 2
- Views: 310
Re: E29 Part D
Since there are 4 moles of oxygen, you just multiply the molar mass of the oxygen by 4. Then, you divide this value by the molar mass of the entire sample.
- Sat Oct 06, 2018 11:42 am
- Forum: SI Units, Unit Conversions
- Topic: Fundamental E3
- Replies: 6
- Views: 563
Re: Fundamental E3
3 more Astatine atoms would be needed to balance the 9 Gallium atoms on the scale because Astatine's molar mass is 3 times more than a Gallium atom.
- Fri Oct 05, 2018 10:19 pm
- Forum: General Science Questions
- Topic: Rounding up with Sig Figs
- Replies: 3
- Views: 353
Re: Rounding up with Sig Figs
When rounding for sig figs with a number that ends in 5, you would round up. So for your example, 2.65 would round to 2.7 for two sig figs.
- Thu Oct 04, 2018 10:46 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Q E27
- Replies: 4
- Views: 411
Re: Q E27
Since water has a molar mass of 18.02 g/mole, you can divide that by Avogadro's number in order to get g/molecule.
(18.02g/mol)/(6.022*10^23molecules/mol)=2.992*10^-23g/molecule
(18.02g/mol)/(6.022*10^23molecules/mol)=2.992*10^-23g/molecule