## Search found 17 matches

Tue Mar 08, 2016 11:23 am
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: final 2012 #5
Replies: 2
Views: 478

### Re: final 2012 #5

In the C-C single bonds in cycloalkanes and cycloalkenes, the carbons are all sp3 hybridized. This means that all the carbons want to be 109.5 degrees away from each other. In cyclooctene, all the C-C single bonds are not 109.5 degrees, because if they were, the ends of the ring would overlap instea...
Sat Feb 06, 2016 11:11 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: assigning half reactions to oxidation/reduction
Replies: 1
Views: 398

### Re: assigning half reactions to oxidation/reduction

When given the cell diagram for a reaction, the anode and oxidation reaction are always on the left, and the cathode and reduction reaction are always on the right. In part C of 14.37, you are given the H+ reaction on the right, and must treat it as the cathode. Even though the final answer means th...
Fri Jan 29, 2016 2:27 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy changes
Replies: 1
Views: 477

### Re: Entropy changes

According to the noble gas equation, PV=nRT, pressure is the inverse of volume, all other things being held constant. Since those equations for entropy are derived from the noble gas equation, using P1/P2 will give you the correct value.
Wed Jan 20, 2016 7:48 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Efficiency
Replies: 1
Views: 285

### Re: Efficiency

When a reaction is efficient, all the heat produced by the reaction is used to do work. An irreversible reaction does less work because some of the heat produced by the reaction leaves the system. In a reversible reaction, all the energy produced by the reaction is used to do work, which is why they...
Thu Jan 14, 2016 3:12 pm
Forum: Phase Changes & Related Calculations
Topic: Calculating Work
Replies: 4
Views: 2254

### Re: Calculating Work

Work is equal to -P*deltaV. The problem tells you that the pressure being applied to the system is 2 atm, so now you just need to find the change in volume. The volume of a cylinder is equal to the area of the base multiplied by the height. The diameter of the pump is 3, which means that the area of...
Thu Jan 07, 2016 10:19 am
Forum: Calculating Work of Expansion
Topic: Expansion of Work 8.3 Self Test
Replies: 1
Views: 528

### Re: Expansion of Work 8.3 Self Test

I think you can do it like this. To find the work here you need to use the equation W=-P * deltaV. In the problem you are given the pressure, 1070 atm, so you just need to find the volume. The change in volume will be the final volume, minus the initial volume, so you will need to find the volume of...
Wed Dec 02, 2015 11:10 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Ka vs. Kb
Replies: 1
Views: 1572

### Re: Ka vs. Kb

Whether you use Ka or Kb depends on what the problem is asking you to do. If in the equation the reactants have an acid mixing with water then you use Ka. If it is a base mixing with water, you use the Kb. If you are not given an equation, you must use your best judgement to determine whether the co...
Tue Nov 24, 2015 8:31 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Delocalization of Negative Charges
Replies: 1
Views: 770

### Re: Delocalization of Negative Charges

Trichloroacetic acid and acetic acid are structurally identical. However trichloroacetic acid has a CCl3+ attached to the acetate ion instead of a CH3+, meaning that it has 3 Cl atoms where H atoms should be. When an acid donates a proton in solution, it leaves behind a negatively charged compound. ...
Sat Nov 21, 2015 12:17 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Ionic Character and Strength of Bonds
Replies: 4
Views: 2195

### Re: Ionic Character and Strength of Bonds

Ionic bonds are formed from the attraction between a positively charged cation, and a negatively charged anion. Water is a polar solvent, so it can dissolve polar compounds. Oxygen is more electronegative than hydrogen, so the central oxygen in a water molecule has a slight negative charge. The oxyg...
Sat Nov 21, 2015 12:12 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Weak acids and equations
Replies: 3
Views: 621

### Re: Weak acids and equations

Ka is the measure of the concentration of H3O+ ions in a solution. All acids have a Ka, but we can calculate the Ka(using the equilibrium equation) of a weak acid because some of the original acid remains in the solution, unionized. Kb is the concentration of OH- ions in a solution. An acid will not...
Wed Nov 11, 2015 5:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Given partial pressure, calculate equilibrium constant
Replies: 2
Views: 562

### Re: Given partial pressure, calculate equilibrium constant

When doing the calculation for Kc, you need to use pascals as the units for pressure. Since you are given the pressure values in kilopascals for the problem you need to divide all your pressure values by 100 to get those values in pascals.
Sun Nov 08, 2015 12:18 am
Forum: Naming
Topic: oxidation and charge
Replies: 1
Views: 402

### Re: oxidation and charge

If a ligand is neutral then its oxidation number is 0. If it is an ion, then its oxidation number is the charge of the ion. The oxidation number of the central metal atom is the difference between the charge of the molecule, and the combined charge of all the ligands. If you are given the name of th...
Wed Oct 28, 2015 7:52 pm
Forum: Ionic & Covalent Bonds
Topic: Workbook Quiz 2 Prep: #9 Which has 2 unpaired electrons?
Replies: 1
Views: 472

### Re: Workbook Quiz 2 Prep: #9 Which has 2 unpaired electrons?

Lewis structures cannot tell you whether or not an atom has unpaired electrons. To figure that out, one must draw the molecular orbital. In this case, OF+ has 12 electrons, so all the orbitals are filled up until PI*2Px and PI*2Py which each get 1 electron, as they are on the same energy level, and ...
Sun Oct 25, 2015 4:21 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Ionic Character and Strength of Bonds
Replies: 4
Views: 2195

### Re: Ionic Character and Strength of Bonds

In general, ionic bonds are stronger than covalent bonds. So the more ionic character a bond has the stronger it is.
Sat Oct 17, 2015 8:22 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Writing electron configurations for ions with d-orbitals
Replies: 1
Views: 393

### Re: Writing electron configurations for ions with d-orbitals

Writing the electron configuration of an ion is all about removing the electrons that require the least energy to remove. For Se, the 5s and 5p orbitals are further away from the nucleus than 4d. Therefore the electrons in the 5s and 5p orbitals are more weakly attracted to the nucleus than those in...
Fri Oct 09, 2015 2:32 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect- Extra Energy
Replies: 1
Views: 336

### Re: Photoelectric Effect- Extra Energy

The excess energy from the photon is translated to the kinetic energy of the ejected electron. The more excess energy, the more kinetic energy the electron has upon being ejected.
Fri Oct 02, 2015 12:02 pm
Forum: Properties of Electrons
Topic: Energy Relationships in Absorption and Emission
Replies: 2
Views: 473

### Re: Energy Relationships in Absorption and Emission

If a photon has enough energy to remove an electron from a material then no electromagnetic radiation will be emitted. Electrons emit EM radiation when they move down energy levels, so an electron that has escaped completely will not move back down energy levels, and therefore will not emit EM radia...