## Search found 32 matches

Fri Jul 28, 2017 8:01 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Icebox for Buffers?
Replies: 5
Views: 1206

### Re: Icebox for Buffers?

When calculating the pH of a buffer solution containing a weak acid/base and its salt, we are making the assumption that the initial concentrations of the acid/base and its respective ion (which is supplied initially by the salt) does not change. This means we are assuming that protonation and depro...
Thu Jul 27, 2017 4:35 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Icebox for Buffers?
Replies: 5
Views: 1206

### Icebox for Buffers?

Why are we not able to use an icebox when calculating the concentration of H3O+ in a buffer solution of a weak base and its salt?
Tue Jul 25, 2017 1:23 am
Forum: Resonance Structures
Topic: Double Bonds in SO2
Replies: 1
Views: 580

### Double Bonds in SO2

When drawing resonance structures for SO2, we see that there are two structures where one O has a single bond and one has a double bond, and a third (most stable) structure where both O atoms get a double bond and S keeps its lone pair of electrons. How would this double bond look in terms of sigma/...
Mon Jul 24, 2017 10:35 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentates
Replies: 3
Views: 405

### Re: Polydentates

Thank you guys!
Mon Jul 24, 2017 9:10 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentates
Replies: 3
Views: 405

### Polydentates

If a ligand has an atom with 2 pairs of lone electrons (like H2O), why is it not able to donate both pairs of electrons to the central atom? Is it possible for a double or triple bond to be formed in a complex between a central atom and an atom in the ligand?
Mon Jul 24, 2017 9:04 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Delocalization
Replies: 1
Views: 304

### Delocalization

When atoms forms molecules, do all electrons become delocalized over the entire molecule, or only the electrons involved in resonance pi bonds? The book mentions that the resonance of the benzene molecule results in the electrons from the C=C double bonds to delocalized over the whole molecule, but ...
Thu Jul 20, 2017 11:30 am
Forum: Naming
Topic: List of Polydentates
Replies: 1
Views: 322

### List of Polydentates

Heres a list of what I believe is the number of binding sites that each polydentate ligand forms. If there's anything I left out or got incorrect, I'd really appreciate any feedback!

En: 2
Dien: 3
Nitrito: 1 (sometimes 2)
Carbonato: 1 (sometimes 2)
Ox: 2
Sulfato: 1 (sometimes 2)
EDTA: 6
Porphyrin: 4
Wed Jul 19, 2017 8:10 pm
Forum: Ideal Gases
Topic: Chemical Equilibrium
Replies: 3
Views: 383

### Re: Chemical Equilibrium

Chemical equilibrium can occur for any chemical reaction, whatever phase the reactants and products are in. Chemical equilibrium only means that the amount of reactants and products are not changing anymore, so this can occur for compounds in any state. When we calculate the equilibrium constant, th...
Wed Jul 19, 2017 7:58 pm
Forum: General Science Questions
Topic: Difference between Free Radical and Ion
Replies: 1
Views: 4034

### Difference between Free Radical and Ion

What's the difference between a free radical and an ion? Would Cl existing by itself be considered to have a free radical because there is only one electron in its pz orbital? Or would N existing by itself have 3 free radicals because each electron in each p orbital exists by itself?
Wed Jul 19, 2017 7:54 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentates
Replies: 1
Views: 325

### Polydentates

So we learned about monodentate ligands with only one atom possessing a lone pair of electrons (i.e. Cl-) and polydentate ligands which have multiple atoms with a lone pair of electrons (ie. oxalato). But without seeing a picture or molecular formula for a molecule, how do we know what type of polyd...
Sat Jul 15, 2017 6:12 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Relationship between Electronegativity and Orbital Energy
Replies: 4
Views: 1379

### Relationship between Electronegativity and Orbital Energy

The answer for question 4.57 says that a higher electronegativity for an atom makes its orbitals have lower energy. Why is that?
Sat Jul 15, 2017 2:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Naming Compounds
Replies: 1
Views: 241

### Naming Compounds

What is the specific wording that will be used to distinguish from the arrangement of electrons around a central atom versus the name we give it? For instance, a AX2E2 molecule has an arrangement of tetrahedral and the name bent.
Sat Jul 15, 2017 11:40 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8017
Views: 1401960

### Re: Post All Chemistry Jokes Here

A photon checks into a hotel and is asked if he needs any help with his luggage. He says, "No, I'm traveling light."
Sat Jul 15, 2017 11:38 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8017
Views: 1401960

### Re: Post All Chemistry Jokes Here

If you're not part of the solution, you're part of the precipitate.
Sat Jul 15, 2017 11:34 am
Forum: Electronegativity
Topic: Electron Affinity
Replies: 12
Views: 1369

### Re: Electron Affinity

Hey! I like to remember trends by thinking of how a trend changes as you move up and to the right of the periodic table. Atomic radius and ionic radius are the biggest in the bottom left (at Cesium), and generally decrease as you move up and to the right. Ionization Energy, Electron Affinity, and El...
Tue Jul 11, 2017 12:28 pm
Forum: Resonance Structures
Topic: SO2 Resonance [ENDORSED]
Replies: 1
Views: 2318

### SO2 Resonance[ENDORSED]

Why does SO2 have 3 resonance structures (one where each oxygen has a double bond, and the others where one oxygen has a double bond and one has a single bond - pg 85 of the course reader) if the first structure has 10 electrons around sulfur and the other structures only have 8 electrons around the...
Sun Jul 09, 2017 4:27 pm
Forum: Properties of Electrons
Topic: Energy of an Electron
Replies: 2
Views: 420

### Energy of an Electron

Why is the energy of an electron negative for any given energy level (according to the equation E=-hR/(n^2))? What does the energy for an electron at a given energy level correspond to (for instance, does a higher energy of an electron change its velocity or wavelength)?
Sun Jul 09, 2017 4:14 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Question about Effective Nuclear Charge
Replies: 3
Views: 356

### Re: Question about Effective Nuclear Charge

Thank you so much!
Sun Jul 09, 2017 1:51 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Question about Effective Nuclear Charge
Replies: 3
Views: 356

### Question about Effective Nuclear Charge

How does Effective Nuclear Charge (Zeff) affect the energy of an electron?
Wed Jul 05, 2017 7:55 pm
Forum: *Shrodinger Equation
Topic: Obtaining the Wave Function
Replies: 3
Views: 457

### Re: Obtaining the Wave Function

Thank you guys so much! Just to make sure I generally understand how it works, here's my overall summary of the equation: The Hamiltonian Operator is defined as the sum of the kinetic energy (which is derived mathematically) and the potential energy (which is determined depending on the system being...
Tue Jul 04, 2017 3:09 pm
Forum: *Shrodinger Equation
Topic: Obtaining the Wave Function
Replies: 3
Views: 457

### Obtaining the Wave Function

What are the steps we need to take to obtain the wave function using Schrodinger's Equation? How are we able to figure out the potential energy function for an electron, and why does taking the double derivative of the wave function help us obtain kinetic energy?
Tue Jul 04, 2017 2:59 pm
Forum: *Particle in a Box
Topic: Conceptualizing Particle in a Box
Replies: 1
Views: 419

### Conceptualizing Particle in a Box

I just wanted to clarify the meaning and application of particle in a box. Is the idea of particle in a box to show that a particle of mass m that is constrained by 2 one-dimensional barriers can only have certain wavelengths, which means that particles have quantized energy levels?
Tue Jul 04, 2017 2:26 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: wave function and orbitals
Replies: 1
Views: 254

### Re: wave function and orbitals

Hi! My understanding is that orbitals were created because of the wave-like properties of electrons, because the wave-like properties of electrons means their exact positions cannot be known exactly. Wave functions are created mathematically to represent probability density of finding electrons in c...
Sun Jul 02, 2017 10:47 pm
Forum: DeBroglie Equation
Replies: 4
Views: 635

I was wondering if you could use the same type of equation as you do for light to relate energy and wavelength, which is E=hc/λ. But instead of using the speed of light, I would substitute in the velocity of the particle. I wasn't sure whether this was a valid technique or not though.
Sun Jul 02, 2017 3:57 pm
Forum: DeBroglie Equation
Topic: Frequency of an Electron?
Replies: 1
Views: 324

### Frequency of an Electron?

So we can calculate the wavelength of an electron (or any other particle) using De Broglie's Equation, λ=h/p. But is there a way to calculate the frequency of these waves, or do we even need to know how to do this at all?
Sun Jul 02, 2017 3:55 pm
Forum: DeBroglie Equation
Topic: Class Lecture Work Example Question [ENDORSED]
Replies: 2
Views: 397

### Re: Class Lecture Work Example Question[ENDORSED]

De Broglie's Equation is λ=h/p, where p=mass x velocity. To calculate the wavelength of an electron, we can plug in the (given) velocity of the electron and the mass of an electron into De Broglie's Equation. The mass of an electron is a constant (9.11E-31 kg). We want the mass in kg because h is gi...
Sun Jul 02, 2017 3:50 pm
Forum: Properties of Light
Topic: Quantum World 1.3
Replies: 3
Views: 381

### Re: Quantum World 1.3

You can also think about it in terms of the way the shape of the wave changes as frequency decreases. If frequency goes, down, this means wavelength goes up, and the wave of light flattens. The wave of light actually describes the oscillation of the electric and magnetic fields as light travels thro...
Sun Jul 02, 2017 3:12 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect
Replies: 5
Views: 764

### Re: Photoelectric Effect

We utilize the formula E=hc/λ if we are given the wavelength of light and want to solve for the energy per photon of the light (or if we are given the energy per photon of the light and want to calculate the wavelength). This equation is really just combining the two equations c=λν and E=hν in order...
Sun Jul 02, 2017 10:03 am
Forum: DeBroglie Equation
Replies: 4
Views: 635

Part a actually does ask for the wavelength of the electron I think.
Sat Jul 01, 2017 5:26 pm
Forum: DeBroglie Equation
Replies: 4
Views: 635

The question asks for the wavelength of an electron that was ejected from a metal surface with a velocity of 3.6 x 10^-3 km/s. I know that one way to solve this is by using the De Broglie equation, but I was just wondering if it was possible to solve this by solving for Kinetic Energy of the electro...
Wed Jun 28, 2017 7:12 pm
Forum: Properties of Light
Topic: energy required to remove an electron [ENDORSED]
Replies: 7
Views: 1609

### Re: energy required to remove an electron[ENDORSED]

It should also be said that the question in the post-assessment asks for the energy required to remove 1 electron, but the work function is given in kJ per mol of electrons. In order to convert this number into the energy (in Joules) to remove a single electron, we first multiply 150.6 kJ by 1000 to...
Wed Jun 28, 2017 5:58 pm
Forum: Empirical & Molecular Formulas
Topic: Difficulty with HW Question F.21 [ENDORSED]
Replies: 1
Views: 330

### Re: Difficulty with HW Question F.21[ENDORSED]

The answer key actually appears to be slightly off with its molar ratio, but the answer still comes out the same. The book divides 0.0924 mmol C by 0.0113 mmol N to get a molar ratio of 8.18C:1N, but this is because they rounded off before finishing their calculations. Without rounding off, the mola...