## Search found 15 matches

Tue Jan 20, 2015 9:40 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Isothermal and reversible reaction with changing P and V
Replies: 1
Views: 294

### Isothermal and reversible reaction with changing P and V

The question states: If 2.00 mol of an ideal gas at 300 K and 3.00 atm expands isothermally and reversibly from 6.00 L to 18.00 L and has a final pressure of 1.20 atm, what is w, q, and delta U. I understand that q is 0 since the reaction is isothermal, and that w=-n(5/2R)Tln(V2/V1) for the changing...
Tue Dec 09, 2014 3:53 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Using the HH Equation
Replies: 1
Views: 272

### Re: Using the HH Equation

You can use the HH equation and still get the same answer. I did this and it worked out. If you notice, the problem says the +/-x values in the expression of Ka are deemed negligible and can be removed. This is basically the Henderson equation which you are left with since you are multiplying the Ka...
Fri Nov 28, 2014 10:30 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 2012 Quiz 3 Number 4
Replies: 4
Views: 512

### Re: 2012 Quiz 3 Number 4

Think back to geometries in Chapter three. Knowing that the shape is square planar tells us that there are 6 available binding sites for the central atom, but only 4 are being occupied by bonds (there are lone pairs present in the other two spots). So, 2 NH2CH2CH2NH2 bond with the atom to give that ...
Fri Nov 21, 2014 12:53 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate bonding
Replies: 1
Views: 243

### Re: Polydentate bonding

When determining how many binding sites a ligand has, the best way to go is drawing the lewis structure out and seeing how many lone pairs would be donated to the metal. For example, ethylenediamine has two lone pairs on each of the nitrogen atoms in the compound, so it would be a bidentate ligand. ...
Wed Nov 19, 2014 7:36 pm
Forum: Naming
Topic: Charge of the metal
Replies: 2
Views: 655

### Re: Charge of the metal

In this compound, we know that [CoF6] is 3- itself since the K has a +1 charge. This is similar to a compound like AlCl3 where the +3 charge on the aluminum crosses over to become a subscript of the chlorine and the -1 charge of the chlorine crosses and becomes a subscript of the Aluminum. So, the [...
Wed Nov 19, 2014 3:41 pm
Forum: Naming
Topic: order of naming
Replies: 1
Views: 296

### Re: order of naming

Yes, the order of naming an ionic compound is cation and then anion. The same order applies to coordination compounds.
Tue Nov 04, 2014 10:45 pm
Forum: Resonance Structures
Topic: Bond Lengths for Resonance Structures
Replies: 2
Views: 1178

### Bond Lengths for Resonance Structures

How do you calculate bond lengths for a molecule with 3 resonance structures? For example: NO32-. Are we expected to know the exact number or is an estimate alright?
Tue Oct 28, 2014 7:43 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: 2.77
Replies: 2
Views: 985

### 2.77

In the homework, 2.77 asks: Use electronegativities to predict which of the following compounds is the more soluble in water: (a) AlCl3 or KCl; (b) MgO or BaO. I understood the answer for part (a) since Al3+ is smaller and more highly charge and causes stronger polarizing power on the anion. For par...
Tue Oct 28, 2014 7:35 pm
Forum: Coordinate Covalent Bonds
Topic: Lewis Acid or Double Bond?
Replies: 3
Views: 961

### Re: Lewis Acid or Double Bond?

In the course of this reaction, the NH3 acts as an electron-pair donor, or Lewis base. The electron-pair acceptor is the boron atom in BF3, which makes this the lewis acid. When the boron atom picks up a pair of electrons from the water molecule, it no longer needs to form double bonds. This is call...
Tue Oct 28, 2014 7:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity and Nonpolarity
Replies: 2
Views: 399

### Re: Polarity and Nonpolarity

Thank you!
Sat Oct 25, 2014 7:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity and Nonpolarity
Replies: 2
Views: 399

### Polarity and Nonpolarity

How can a molecule can have polar bonds but be nonpolar overall. Can the opposite ever be true?
Fri Oct 17, 2014 9:18 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence Electrons
Replies: 3
Views: 4846

### Re: Valence Electrons

Valence electrons are any electrons after the closest noble gas to the element you are looking at. Cobalt will have 9 valence electrons since the d level electrons are counted. D level electrons are slightly higher in energy than the next level's s orbital. For exmaple: 3d is at a higher energy leve...
Tue Oct 14, 2014 6:54 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Workbook Quiz #1 Practice Test 3 Last Question
Replies: 1
Views: 463

### Workbook Quiz #1 Practice Test 3 Last Question

For this problem about finding the principal quantum number from a given frequency, I used the equation frequency=R(1/n(initial)^2-1/n(final)^2), but i got a decimal answer for my n value. Is this possible? Or am I doing something wrong?
Tue Oct 14, 2014 6:49 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Energy Levels
Replies: 4
Views: 657

### Re: Energy Levels

"n" is the principal quantum level. Each n value represents an orbital with a certain amount of energy. n=1 is closest to the nucleus, and as n increases the energy increases as well since you are getting further and further away from the nucleus. It takes more energy to excite an electron...
Wed Oct 08, 2014 10:11 pm
Forum: Photoelectric Effect
Topic: Energy to remove an electron
Replies: 3
Views: 446

### Energy to remove an electron

In lecture it was briefly discussed that an electron will not be emitted if the energy of a photon is greater than or equal to the energy o needed to remove an electron from the surface of a metal. I was wondering why this is so. Is there not supposed to be any excess energy?