Search found 31 matches

by Rita Dang 3D
Sat Dec 09, 2017 4:29 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Seesaw
Replies: 2
Views: 266

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.
by Rita Dang 3D
Fri Dec 08, 2017 9:11 pm
Forum: Biological Examples
Topic: Biological Importance
Replies: 2
Views: 261

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.
by Rita Dang 3D
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: 248

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.
by Rita Dang 3D
Wed Nov 29, 2017 9:54 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 17.33 Homework
Replies: 1
Views: 140

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...
by Rita Dang 3D
Wed Nov 29, 2017 9:43 am
Forum: Dipole Moments
Topic: Dipole moments and Formal Charges
Replies: 2
Views: 224

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...
by Rita Dang 3D
Tue Nov 28, 2017 10:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW 11.43
Replies: 1
Views: 98

Re: HW 11.43

Professor Lavelle just updated the solution manual errors.
It should be "x is the equilibrium partial pressure."
by Rita Dang 3D
Wed Nov 22, 2017 10:03 am
Forum: Naming
Topic: di, bis, tri, tris, etc
Replies: 4
Views: 234

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).
by Rita Dang 3D
Wed Nov 22, 2017 9:59 am
Forum: Dipole Moments
Topic: Dipole Moments
Replies: 2
Views: 184

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...
by Rita Dang 3D
Sat Nov 18, 2017 5:04 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Sigma and Pi Bonds
Replies: 3
Views: 263

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.
by Rita Dang 3D
Sat Nov 18, 2017 4:50 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent or linear?
Replies: 11
Views: 667

Re: Bent or linear?

I think it would be linear if there are no lone pairs on the central atom
by Rita Dang 3D
Thu Nov 16, 2017 11:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 2
Views: 140

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)?
by Rita Dang 3D
Sat Nov 11, 2017 3:37 pm
Forum: Ionic & Covalent Bonds
Topic: Valence of an Atom [ENDORSED]
Replies: 3
Views: 207

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.
by Rita Dang 3D
Sat Nov 11, 2017 3:32 pm
Forum: Lewis Structures
Topic: HOCO [ENDORSED]
Replies: 3
Views: 252

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.
by Rita Dang 3D
Tue Oct 31, 2017 1:05 pm
Forum: Trends in The Periodic Table
Topic: Negative Electron Affinity
Replies: 2
Views: 257

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?
by Rita Dang 3D
Tue Oct 31, 2017 12:48 pm
Forum: Trends in The Periodic Table
Topic: 2.67
Replies: 5
Views: 280

Re: 2.67

Can anyone explain to me why Cl has a higher electron affinity than Br?
by Rita Dang 3D
Tue Oct 31, 2017 12:44 pm
Forum: Trends in The Periodic Table
Topic: 2.67
Replies: 5
Views: 280

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.
by Rita Dang 3D
Sat Oct 28, 2017 5:15 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity [ENDORSED]
Replies: 5
Views: 320

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?
by Rita Dang 3D
Sat Oct 28, 2017 1:58 pm
Forum: Significant Figures
Topic: 300 vs 300. [ENDORSED]
Replies: 8
Views: 547

300 vs 300. [ENDORSED]

Just to make sure. 300 has only 1 sig fig. And 300. has 3 sig figs right?
by Rita Dang 3D
Sat Oct 28, 2017 1:56 pm
Forum: Trends in The Periodic Table
Topic: D-block valence electrons? [ENDORSED]
Replies: 4
Views: 2165

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.
by Rita Dang 3D
Wed Oct 18, 2017 12:32 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: ch1 question 43
Replies: 8
Views: 583

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.
by Rita Dang 3D
Wed Oct 18, 2017 12:25 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Post Module Question #16
Replies: 2
Views: 161

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.
by Rita Dang 3D
Wed Oct 11, 2017 2:49 pm
Forum: Einstein Equation
Topic: Question about Ek
Replies: 3
Views: 251

Re: Question about Ek

^2 only applies to v, not the whole equation.
by Rita Dang 3D
Wed Oct 11, 2017 12:33 pm
Forum: Properties of Light
Topic: 1.15 Homework Question
Replies: 2
Views: 165

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.
by Rita Dang 3D
Wed Oct 11, 2017 12:26 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect: Post Module Assessment Q. 28, 29, and 30
Replies: 12
Views: 601

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.
by Rita Dang 3D
Mon Oct 09, 2017 10:09 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect: Post Module Assessment Q. 28, 29, and 30
Replies: 12
Views: 601

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.
by Rita Dang 3D
Mon Oct 09, 2017 10:06 pm
Forum: Photoelectric Effect
Topic: Q31 from online assessment
Replies: 4
Views: 294

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-)
by Rita Dang 3D
Sat Oct 07, 2017 11:19 pm
Forum: Photoelectric Effect
Topic: Question from online assessment [ENDORSED]
Replies: 1
Views: 124

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?
by Rita Dang 3D
Sat Oct 07, 2017 11:15 pm
Forum: Photoelectric Effect
Topic: Q31 from online assessment
Replies: 4
Views: 294

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...
by Rita Dang 3D
Thu Oct 05, 2017 10:20 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: #of molecules/atoms/formula units
Replies: 3
Views: 238

#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?
by Rita Dang 3D
Wed Oct 04, 2017 2:34 pm
Forum: Significant Figures
Topic: Theoretical and Percentage Yield
Replies: 4
Views: 334

Re: Theoretical and Percentage Yield

Side reactions and impurities can also cause differences between actual and theoretical yield.
by Rita Dang 3D
Mon Oct 02, 2017 10:59 pm
Forum: Empirical & Molecular Formulas
Topic: M21
Replies: 1
Views: 149

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...

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