Search found 31 matches
- Sat Dec 09, 2017 4:29 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Seesaw
- Replies: 2
- Views: 340
Re: Seesaw
It refers to the fact that the stronger the acid, the weaker its conjugate base, and the stronger the base, the weaker its conjugate acid.
- Fri Dec 08, 2017 9:11 pm
- Forum: Biological Examples
- Topic: Biological Importance
- Replies: 2
- Views: 319
Re: Biological Importance
Chromium regulates glucose metabolism. Iron facilitates oxygen transportation. Cobalt (Vitamin B12) prevents anemia and mental illness. Zinc is a master hormone that is critical for enzyme function.
- Wed Nov 29, 2017 9:57 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 4
- Views: 851
Re: Le Chatelier's Principle
If the reaction is exothermic, taking away heat will make the reaction favor the products. If the reaction is endothermic, taking away heat will make the reaction favor reactants.
- Wed Nov 29, 2017 9:54 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: 17.33 Homework
- Replies: 1
- Views: 204
Re: 17.33 Homework
To determine the number of binding sites, we look at the number of atoms that have extra lone pairs to donate, not the number of lone pairs one atom has. H2O is monodentate because the Oxygen atom is the only atom that have extra electron pairs. Oxalate is bidentate because it has two Oxygen atoms t...
- Wed Nov 29, 2017 9:43 am
- Forum: Dipole Moments
- Topic: Dipole moments and Formal Charges
- Replies: 2
- Views: 311
Dipole moments and Formal Charges
Does anyone know if we need to look at the formal charges when determine whether the dipole moments cancel or not? I know we need to draw the lewis structure and consider the shape first. And then see if the partial charges cancel or not. But is formal charge related to partial charges and the conce...
- Tue Nov 28, 2017 10:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: HW 11.43
- Replies: 1
- Views: 152
Re: HW 11.43
Professor Lavelle just updated the solution manual errors.
It should be "x is the equilibrium partial pressure."
It should be "x is the equilibrium partial pressure."
- Wed Nov 22, 2017 10:03 am
- Forum: Naming
- Topic: di, bis, tri, tris, etc
- Replies: 4
- Views: 367
Re: di, bis, tri, tris, etc
We use bis- and tris- instead of di- and tri- when the ligand is polydentate, such as EDTA (6 binding sites) and en (2 binding sites).
- Wed Nov 22, 2017 9:59 am
- Forum: Dipole Moments
- Topic: Dipole Moments
- Replies: 2
- Views: 260
Re: Dipole Moments
I think dipole moments depend on the electronegativity of each element and also the structure of the compound. By looking at the structure of a compound and determining its shape, we can decide whether the dipole moments cancel each other or not. In other words, we need to know the lewis structure a...
- Sat Nov 18, 2017 5:04 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Sigma and Pi Bonds
- Replies: 3
- Views: 401
Re: Sigma and Pi Bonds
The key distinction between a sigma and a pi bond is that a sigma bond is formed by an end-by-end overlap while a pi bond is formed by a side-by-side overlap. Sigma bond is always the first bond formed between 2 atoms. All single covalent bonds are sigma bonds.
- Sat Nov 18, 2017 4:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent or linear?
- Replies: 11
- Views: 1087
Re: Bent or linear?
I think it would be linear if there are no lone pairs on the central atom
- Thu Nov 16, 2017 11:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 2
- Views: 199
Bond Angles
When we try to predict or determine bond angles, do we look at the electron distribution instead of the shape (or positions of atoms)?
- Sat Nov 11, 2017 3:37 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence of an Atom [ENDORSED]
- Replies: 3
- Views: 346
Re: Valence of an Atom [ENDORSED]
It is basically saying that the number of covalent bonds depends on the valence of an atom. For instance, Carbon has 4 valence electrons, and therefore it can form 4 covalent bonds with other atoms. Hydrogen only has 1 valence electron, and therefore it can only form 1 covalent bond.
- Sat Nov 11, 2017 3:32 pm
- Forum: Lewis Structures
- Topic: HOCO [ENDORSED]
- Replies: 3
- Views: 358
Re: HOCO [ENDORSED]
Remember when drawing Lewis Structures, we almost always have to satisfy the octet rule for Oxygen first because it has a high electronegativity.
- Tue Oct 31, 2017 1:05 pm
- Forum: Trends in The Periodic Table
- Topic: Negative Electron Affinity
- Replies: 2
- Views: 340
Negative Electron Affinity
Does negative electron affinity mean energy must be supplied to push an electron onto an atom?
If so, would more negative electron affinity mean lower electron affinity since it takes more energy for the atom to gain an electron?
If so, would more negative electron affinity mean lower electron affinity since it takes more energy for the atom to gain an electron?
- Tue Oct 31, 2017 12:48 pm
- Forum: Trends in The Periodic Table
- Topic: 2.67
- Replies: 5
- Views: 435
Re: 2.67
Can anyone explain to me why Cl has a higher electron affinity than Br?
- Tue Oct 31, 2017 12:44 pm
- Forum: Trends in The Periodic Table
- Topic: 2.67
- Replies: 5
- Views: 435
Re: 2.67
Carbon has a higher electron affinity than nitrogen because nitrogen is already in its half-filled stable state. Carbon is more likely to gain one more electron so it can reach a more stable state.
- Sat Oct 28, 2017 5:15 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity [ENDORSED]
- Replies: 5
- Views: 495
Re: Electron Affinity [ENDORSED]
Since Phosphorus is a half-filled subshelled atom (already in its stable state), Sulfur has a greater electron affinity than Phosphorus right?
- Sat Oct 28, 2017 1:58 pm
- Forum: Significant Figures
- Topic: 300 vs 300. [ENDORSED]
- Replies: 8
- Views: 897
300 vs 300. [ENDORSED]
Just to make sure. 300 has only 1 sig fig. And 300. has 3 sig figs right?
- Sat Oct 28, 2017 1:56 pm
- Forum: Trends in The Periodic Table
- Topic: D-block valence electrons? [ENDORSED]
- Replies: 4
- Views: 4605
Re: D-block valence electrons? [ENDORSED]
Zinc only has two valence electrons. It has 30 electrons in its outer shell. Its electron configuration is [Ar]3d^10 4s^2. 4s is its outer most shell, which contains 2 electrons.
- Wed Oct 18, 2017 12:32 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: ch1 question 43
- Replies: 8
- Views: 766
Re: ch1 question 43
The equation the solutions manual uses is the same thing as ∆p∆x=h/4pi. The "h" the solution manual uses in the equation ∆p∆x= "h"/2 represents h/2pi, which is the same thing as h/4pi if you multiply it out.
- Wed Oct 18, 2017 12:25 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Post Module Question #16
- Replies: 2
- Views: 243
Re: Post Module Question #16
The significance behind Heisenberg's uncertainty (indeterminacy) equation is that measurement process influence outcome at atomic level. The more we know about an electron's momentum the less we know about its position. So I think C is the correct answer.
- Wed Oct 11, 2017 2:49 pm
- Forum: Einstein Equation
- Topic: Question about Ek
- Replies: 3
- Views: 344
Re: Question about Ek
^2 only applies to v, not the whole equation.
- Wed Oct 11, 2017 12:33 pm
- Forum: Properties of Light
- Topic: 1.15 Homework Question
- Replies: 2
- Views: 234
Re: 1.15 Homework Question
Since the question tells us that the line is observed in the ultraviolet spectrum of atomic hydrogen, we can infer the line being observed belong to the Lyman series (by the definition of Lyman series). In Lyman series, we always have n_1=1.
- Wed Oct 11, 2017 12:26 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect: Post Module Assessment Q. 28, 29, and 30
- Replies: 12
- Views: 887
Re: Photoelectric Effect: Post Module Assessment Q. 28, 29, and 30
You always plug in 9.109x10^-31kg for m if you are calculating the kinetic energy of an electron.
- Mon Oct 09, 2017 10:09 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect: Post Module Assessment Q. 28, 29, and 30
- Replies: 12
- Views: 887
Re: Photoelectric Effect: Post Module Assessment Q. 28, 29, and 30
For 29, convert kJ to J first and then divide the number by the number of atoms per mole.
- Mon Oct 09, 2017 10:06 pm
- Forum: Photoelectric Effect
- Topic: Q31 from online assessment
- Replies: 4
- Views: 547
Re: Q31 from online assessment
These are my steps: hv-150600J.mol^-1=1.99x10^-19J
hv=150600J
v=2.27x10^38HZ
So I basically plugged numbers into the formula E(photon)-E(energy remove e-)=E_k(e-)
hv=150600J
v=2.27x10^38HZ
So I basically plugged numbers into the formula E(photon)-E(energy remove e-)=E_k(e-)
- Sat Oct 07, 2017 11:19 pm
- Forum: Photoelectric Effect
- Topic: Question from online assessment [ENDORSED]
- Replies: 1
- Views: 144
Question from online assessment [ENDORSED]
The question asks "in photoelectric experiments, typically what part of the electromagnetic spectrum is the incoming light?"
I know the answer is Ultraviolet. But why?
I know the answer is Ultraviolet. But why?
- Sat Oct 07, 2017 11:15 pm
- Forum: Photoelectric Effect
- Topic: Q31 from online assessment
- Replies: 4
- Views: 547
Q31 from online assessment
Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1. Answer the following three questions. A. What is the kinetic energy of the ejected electron? B. How much energy is required to remove an electron from one s...
- Thu Oct 05, 2017 10:20 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: #of molecules/atoms/formula units
- Replies: 3
- Views: 326
#of molecules/atoms/formula units
When a question asks about the number of molecules, atoms, or formula units, is it asking for the same thing?
- Wed Oct 04, 2017 2:34 pm
- Forum: Significant Figures
- Topic: Theoretical and Percentage Yield
- Replies: 4
- Views: 493
Re: Theoretical and Percentage Yield
Side reactions and impurities can also cause differences between actual and theoretical yield.
- Mon Oct 02, 2017 10:59 pm
- Forum: Empirical & Molecular Formulas
- Topic: M21
- Replies: 1
- Views: 173
M21
The question tells us that the compound is made of carbon, hydrogen, oxygen, and nitrogen, and it asks us to find its empirical formula. I know how to figure out the moles of each element and the ratio between them. But how do you know which element goes first when you write the formula? Like does i...