Search found 64 matches

by Samantha Ito 2E
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: 398

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).
by Samantha Ito 2E
Tue Mar 12, 2019 10:59 pm
Forum: General Science Questions
Topic: Organic Molec Naming?
Replies: 2
Views: 246

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.
by Samantha Ito 2E
Thu Mar 07, 2019 10:01 pm
Forum: Second Order Reactions
Topic: Half life of a second order reaction
Replies: 1
Views: 92

Re: Half life of a second order reaction

Yes, t½ = 1 / k [A]o
by Samantha Ito 2E
Thu Mar 07, 2019 9:58 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 4
Views: 120

Re: Test 2

Rusting is spontaneous because it naturally occurs without any outside intervention even though it happens over a long period of time.
by Samantha Ito 2E
Thu Mar 07, 2019 9:51 pm
Forum: Balancing Redox Reactions
Topic: Test #2
Replies: 6
Views: 166

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.
by Samantha Ito 2E
Thu Mar 07, 2019 9:38 pm
Forum: General Science Questions
Topic: Final
Replies: 7
Views: 417

Re: Final

I don't think he does.
by Samantha Ito 2E
Thu Mar 07, 2019 9:15 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox Reactions
Replies: 4
Views: 117

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...
by Samantha Ito 2E
Thu Mar 07, 2019 5:54 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating Eºcell
Replies: 2
Views: 69

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.
by Samantha Ito 2E
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: 52

Re: 7th edition 6N.1(b)

I noticed that too and I think it is an error in the solutions manual.
by Samantha Ito 2E
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: 80

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?
by Samantha Ito 2E
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: 8049

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

Can someone please explain #4 on the Gibbs Free Energy worksheet?
by Samantha Ito 2E
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: 123

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.
by Samantha Ito 2E
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: 191

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.
by Samantha Ito 2E
Sun Feb 17, 2019 1:32 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: reversible and irreversible processes
Replies: 6
Views: 288

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).
by Samantha Ito 2E
Sun Feb 17, 2019 1:20 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: state functions and properties
Replies: 7
Views: 298

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.
by Samantha Ito 2E
Sun Feb 17, 2019 1:17 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: calculating delta S
Replies: 4
Views: 72

Re: calculating delta S

Boyle's Law states that P1V1=P2V2 and by rearranging the equation, you are left with V2/V1 = P1/P2.
by Samantha Ito 2E
Sun Feb 17, 2019 1:12 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: constant C
Replies: 7
Views: 239

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.
by Samantha Ito 2E
Sat Feb 09, 2019 8:35 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 7th edition 4E.5
Replies: 3
Views: 89

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.
by Samantha Ito 2E
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: 87

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...
by Samantha Ito 2E
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: 64

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?
by Samantha Ito 2E
Sun Feb 03, 2019 1:19 pm
Forum: Phase Changes & Related Calculations
Topic: State Function
Replies: 10
Views: 149

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.
by Samantha Ito 2E
Sat Feb 02, 2019 3:45 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Seventh edition ? 4C.13
Replies: 1
Views: 71

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...
by Samantha Ito 2E
Sat Feb 02, 2019 3:15 pm
Forum: Phase Changes & Related Calculations
Topic: Heat Curve
Replies: 6
Views: 114

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).
by Samantha Ito 2E
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: 102

Re: 7th edition 5J.5 part b

You have to compare the number of moles of gas (don't include the solid).
by Samantha Ito 2E
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: 8049

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

Can someone please indicate the main steps to solve worksheet 1 problem #5?
by Samantha Ito 2E
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: 65

Re: 7th Edition 6B.9

So then would the pOH of the solution be above 14?
by Samantha Ito 2E
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: 65

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
by Samantha Ito 2E
Wed Jan 16, 2019 10:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Endothermic Reaction
Replies: 4
Views: 83

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.
by Samantha Ito 2E
Wed Jan 16, 2019 9:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH
Replies: 5
Views: 101

Re: pH

The pH of a solution is the -log of the hydronium ion concentration: pH = -log[H3O+]
by Samantha Ito 2E
Wed Jan 16, 2019 2:07 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5% approximation for weak acids/bases
Replies: 2
Views: 70

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.
by Samantha Ito 2E
Fri Jan 11, 2019 9:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration of P using the Quadratic Formula
Replies: 2
Views: 44

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.
by Samantha Ito 2E
Fri Jan 11, 2019 9:26 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Changing Pressure
Replies: 6
Views: 138

Re: Changing Pressure

Decreasing the volume of a contained gas will increase its pressure, and increasing its volume will decrease its pressure.
by Samantha Ito 2E
Fri Jan 11, 2019 12:20 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7th Edition 5H.3
Replies: 3
Views: 86

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.
by Samantha Ito 2E
Tue Dec 04, 2018 8:03 pm
Forum: Identifying Acidic & Basic Salts
Topic: Identifying the Different Types of Acidic and Bases
Replies: 2
Views: 35

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.
by Samantha Ito 2E
Sun Dec 02, 2018 9:47 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 7th Edition Focus 9C.5b [ENDORSED]
Replies: 2
Views: 94

7th Edition Focus 9C.5b [ENDORSED]

Can someone explain why CO3^2- serves as a monodentate or bidentate?
by Samantha Ito 2E
Fri Nov 30, 2018 11:51 pm
Forum: Sigma & Pi Bonds
Topic: Strength of Sigma and Pi Bonds
Replies: 5
Views: 333

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.
by Samantha Ito 2E
Fri Nov 30, 2018 11:42 pm
Forum: Resonance Structures
Topic: Resonance
Replies: 4
Views: 232

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...
by Samantha Ito 2E
Fri Nov 30, 2018 9:10 pm
Forum: Lewis Acids & Bases
Topic: Differentiating Between Lewis and Bronsted
Replies: 2
Views: 70

Re: Differentiating Between Lewis and Bronsted

Bronsted acids donate protons and Bronsted bases accept protons. Lewis acids accept electrons and Lewis bases donate electrons.
by Samantha Ito 2E
Tue Nov 27, 2018 8:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Exam
Replies: 3
Views: 103

Re: Exam

It's the end of chemical bonding and all of molecular shape and structure.
by Samantha Ito 2E
Sun Nov 25, 2018 2:13 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 7
Views: 156

Re: Molecular Shape

seesaw shape.jpg
Hope this helps you to visualize it!
by Samantha Ito 2E
Sun Nov 25, 2018 2:10 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 7
Views: 156

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.
by Samantha Ito 2E
Sun Nov 25, 2018 1:54 am
Forum: Octet Exceptions
Topic: Exceptions
Replies: 3
Views: 267

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...
by Samantha Ito 2E
Sun Nov 25, 2018 1:40 am
Forum: Hybridization
Topic: pi and sigma bonds
Replies: 3
Views: 60

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.
by Samantha Ito 2E
Sun Nov 18, 2018 9:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Trigonal Bipyramidal
Replies: 3
Views: 89

Re: Trigonal Bipyramidal

220pcl5.gif
I find it helpful to look at photos of molecules to understand their shapes, so I hope this helps!
by Samantha Ito 2E
Sun Nov 18, 2018 9:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Octahedral to Square Planar
Replies: 7
Views: 116

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.
by Samantha Ito 2E
Sun Nov 18, 2018 9:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T Shaped
Replies: 3
Views: 101

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...
by Samantha Ito 2E
Sat Nov 10, 2018 11:54 pm
Forum: Electronegativity
Topic: Electronegativity and Electron Affinity
Replies: 4
Views: 157

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.
by Samantha Ito 2E
Sat Nov 10, 2018 11:38 pm
Forum: Bond Lengths & Energies
Topic: VSEPR Model
Replies: 1
Views: 52

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.
by Samantha Ito 2E
Sat Nov 10, 2018 11:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: molecular shape
Replies: 3
Views: 132

Re: molecular shape

I think that the only molecular shapes that we have to know are the ones we discuss in lectures.
by Samantha Ito 2E
Sat Nov 03, 2018 2:24 pm
Forum: Lewis Structures
Topic: Lewis Base & Acid
Replies: 2
Views: 90

Re: Lewis Base & Acid

Lewis bases donate pairs of electrons (not protons) and Lewis acids accept pairs of electrons.
by Samantha Ito 2E
Sat Nov 03, 2018 2:19 pm
Forum: Student Social/Study Group
Topic: Orbitals
Replies: 2
Views: 62

Re: Orbitals

I think of the ml as the integers ranging from -l to +l.
by Samantha Ito 2E
Sat Nov 03, 2018 2:16 pm
Forum: Student Social/Study Group
Topic: Studying
Replies: 7
Views: 434

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.
by Samantha Ito 2E
Wed Oct 24, 2018 12:03 am
Forum: *Particle in a Box
Topic: Energy of shells vs. subshells
Replies: 2
Views: 311

Re: Energy of shells vs. subshells

I believe that s- electrons have a lower energy than p- electrons within the same shell.
by Samantha Ito 2E
Tue Oct 23, 2018 11:56 pm
Forum: Properties of Light
Topic: Electromagnetic Spectrum
Replies: 5
Views: 202

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
by Samantha Ito 2E
Mon Oct 22, 2018 8:08 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Quantum World Worksheet #7
Replies: 2
Views: 141

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...
by Samantha Ito 2E
Sun Oct 21, 2018 2:21 am
Forum: Photoelectric Effect
Topic: spectral lines
Replies: 6
Views: 125

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.
by Samantha Ito 2E
Sun Oct 21, 2018 2:18 am
Forum: Photoelectric Effect
Topic: spectral lines
Replies: 6
Views: 125

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.
by Samantha Ito 2E
Sun Oct 21, 2018 2:05 am
Forum: Photoelectric Effect
Topic: spectral lines
Replies: 6
Views: 125

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.
by Samantha Ito 2E
Sat Oct 13, 2018 7:01 pm
Forum: Properties of Light
Topic: E=hv
Replies: 13
Views: 281

Re: E=hv

E stands for energy per photon.
by Samantha Ito 2E
Sat Oct 13, 2018 6:59 pm
Forum: Properties of Light
Topic: Relationship with Equations
Replies: 2
Views: 37

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...
by Samantha Ito 2E
Tue Oct 09, 2018 2:41 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E29 Part D
Replies: 2
Views: 157

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.
by Samantha Ito 2E
Sat Oct 06, 2018 11:42 am
Forum: SI Units, Unit Conversions
Topic: Fundamental E3
Replies: 6
Views: 193

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.
by Samantha Ito 2E
Fri Oct 05, 2018 10:19 pm
Forum: General Science Questions
Topic: Rounding up with Sig Figs
Replies: 3
Views: 153

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.
by Samantha Ito 2E
Thu Oct 04, 2018 10:46 pm
Forum: Molarity, Solutions, Dilutions
Topic: Q E27
Replies: 4
Views: 110

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

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