## Search found 27 matches

Tue Feb 10, 2015 7:18 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Why is Ka the square root of K
Replies: 3
Views: 1092

### Re: Why is Ka the square root of K

When you calculated K for the redox reaction you were calculating [H+]2[F-]2/[HF]2 because the coefficients of the balanced redox reaction were 2 for H+, F-, and HF. However, Ka=[H+][F-]/[HF]. So, Ka=square root K.
Sun Jan 25, 2015 10:55 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 7.57b homework problem
Replies: 1
Views: 556

### Re: 7.57b homework problem

Yes, it is true that q reaction =-q calorimeter for all bomb calorimeter questions. This is because q system =-q surroundings . We know deltaU=w+q and in a bomb calorimeter volume is constant which means there is no change in volume and therefore no work done on or by the system (w=0). So, we have d...
Sun Jan 18, 2015 11:31 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Determining temperature of a reaction (7.51)
Replies: 1
Views: 414

### Determining temperature of a reaction (7.51)

Problem 7.51 asks for the change in internal energy for the reaction of 1.00 mol OF 2 with hydrogen that produces O 2 and HF. When calculating the work you use the ideal gas law PV=nRT. What I don't understand is how you determine temperature if it is not given in the problem. The solutions manual u...
Sun Jan 11, 2015 11:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Contribution to the heat capacity by molecular motions
Replies: 3
Views: 934

### Contribution to the heat capacity by molecular motions

Problem 7.29 asks you to predict the contribution to the linear heat capacity CV/m made by molecular motions of the following atoms and molecules: (a) HCN (b) C2H6 (c) Ar (d) HBr.
Can someone please explain how to go about doing this problem? Thank you.
Tue Dec 09, 2014 11:14 pm
Forum: Lewis Structures
Topic: Lewis Structure of BrO2- vs ClO2-
Replies: 1
Views: 1887

### Lewis Structure of BrO2- vs ClO2-

The structure of BrO 2 - has Br single bonded to each O. The Br has 2 lone pairs and each O has 3 lone pairs. The structure of ClO 2 - has Cl double bonded to one O and single bonded to the other O. The Cl has 2 lone pairs, the first O has 2 lone pairs and the other O has 3 lone pairs. There are 2 r...
Tue Dec 09, 2014 12:19 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle- Temperature
Replies: 6
Views: 1767

### Re: Le Chatelier's Principle- Temperature

Think of energy (in this case heat) as a reactant or product. In an exothermic reaction heat is a product, so if you increase the temperature (more heat) the reaction will favor the reactants and K will decrease. In an endothermic reaction heat is a reactant, so if you increase the temperature (more...
Tue Dec 09, 2014 12:16 am
Forum: DeBroglie Equation
Topic: Neutron and Electron Wavelength
Replies: 2
Views: 1150

### Re: Neutron and Electron Wavelength

You use the de Broglie wavelength equation wavelength=h/p=h/(mv), however you need to know the velocities of the electron and neutron. If you are referring to the question3B on the midterm, it is given that the neutron and electron have the same speed. So, since a neutron has a greater mass its wave...
Sat Dec 06, 2014 4:15 pm
Forum: Student Social/Study Group
Topic: 14B Lecture 1 Discussion Switch
Replies: 1
Views: 684

### 14B Lecture 1 Discussion Switch

Hey! So I'm enrolled in Discussion 1K (Friday 12-12:50) and want to switch to Thursday, however, only the 1I (1-1:50) discussion fits in my schedule. So if anyone in 1I would be willing to switch into 1K let me know!
Thu Dec 04, 2014 8:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chapter 10 #5
Replies: 1
Views: 263

### Re: Chapter 10 #5

To find K you need to first find the partial pressures which can be calculated for each product and reactant by multiplying the respective mole fraction and the total pressure. For example, Px= [(12 mols x)/(17 total mols)](0.1).
Then, you plug those partial pressures into the K equation to find K.
Thu Dec 04, 2014 2:32 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligand-edta
Replies: 2
Views: 366

### Re: Ligand-edta

The full ligand name is ethylenediaminetetraacetato.
Tue Dec 02, 2014 7:42 pm
Forum: Naming
Topic: Knowing whether the compound has net neutral charge or not
Replies: 7
Views: 923

### Re: Knowing whether the compound has net neutral charge or n

I think the problem would have to specify that the compound has a charge, otherwise you can assume the total charge is 0. Also, I don't think we've had a problem in which the compound has a charge.
Tue Dec 02, 2014 7:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Quiz 3 Prep Fall 2012 #5
Replies: 3
Views: 452

### Re: Quiz 3 Prep Fall 2012 #5

But, won't the equilibrium constant be different depending on which coefficient you used? In other words, Kp= PH23/2 will not be equal to Kp= PH23? But both are right?
Sun Nov 30, 2014 11:37 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: K value for changes in temperature
Replies: 2
Views: 490

### Re: K value for changes in temperature

Think of energy (in this case heat) as a reactant or product. In an exothermic reaction heat is a product, so if you increase the temperature (more heat) the reaction will favor the reactants and K will decrease. In an endothermic reaction heat is a reactant, so if you increase the temperature (more...
Sun Nov 30, 2014 11:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Quiz 3 Prep Fall 2012 #5
Replies: 3
Views: 452

### Quiz 3 Prep Fall 2012 #5

#5 reads "At high temperature NaAl 4 decomposes to give NaH, Al, and Hydrogen gas. Given the following balanced reaction, NaAl 4(s) ->NaH (s) + Al (s) + 3/2H 2(g) , write the equilibrium expression. The given answer is K p = P H2 3/2 or K c = [H2] 3/2 OR K p = P ...
Sun Nov 30, 2014 10:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework #69
Replies: 1
Views: 391

### Re: Homework #69

Adjusting the initial condition does not relate to the value of K being so small. In other words, we could adjust the initial condition for any value of K. In this problem (and other problems with small K values), the very small K value allows us to ignore the change in the reactant (HCl) because 2x...
Tue Nov 25, 2014 5:25 pm
Forum: Ionic & Covalent Bonds
Topic: 2014 Midterm question 7. Structure of HCLO3
Replies: 3
Views: 608

### Re: 2014 Midterm question 7. Structure of HCLO3

No, we only consider resonance when we are dealing with electrons because electrons are free to move around to the different atoms. The hydrogen atom is bonded to only one oxygen and cannot move around. Hopefully that makes sense.
Sun Nov 23, 2014 8:52 pm
Forum: Naming
Topic: Using prefixes bis-, tris-, etc.
Replies: 3
Views: 691

### Using prefixes bis-, tris-, etc.

I know that you use these prefixes if the ligand has a name with di-, tri-, etc. but in 16.29 (d) sodium bisoxalato(diaqua)ferrate (III) and 16.30 (d) sodium tris(oxalato)rhodium(III) the book uses bis- and tris- in front of oxalato. Why? Also, why are diaqua (in 16.29d) and oxalato (16.30d) in pare...
Sun Nov 23, 2014 8:32 pm
Forum: Ionic & Covalent Bonds
Topic: 2014 Midterm question 7. Structure of HCLO3
Replies: 3
Views: 608

### Re: 2014 Midterm question 7. Structure of HCLO3

Most acids have an -OH branching off of them. I think that is the only clue that would give you the right structure.
Sun Nov 23, 2014 8:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2014 Midterm question 7. Structure of HCLO3
Replies: 1
Views: 743

### Re: 2014 Midterm question 7. Structure of HCLO3

Most acids have an -OH branching off of them. I think that is the only clue that would give you the right structure.
Sun Nov 16, 2014 10:34 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating complexes (16.33 and 16.34)
Replies: 1
Views: 419

### Chelating complexes (16.33 and 16.34)

I understand that the bonding atoms in a ligand must be close together for the ligand to form a chelating complex but how close must the bonding atoms be? In 16.33, which reads "Which one of the following isomers of diaminobenzene can form chelating complexes?", the answer is only (b). Doe...
Sun Nov 16, 2014 10:13 pm
Forum: Hybridization
Topic: Fall 2011 Midterm 6C and fall 2012 midterm 6A
Replies: 3
Views: 551

### Re: Fall 2011 Midterm 6C and fall 2012 midterm 6A

Sorry I didn't see this sooner! I don't know if this is irrelevant now since it's after the midterm...but I guess there's always the final... Each atom must have a completed octet (8 electrons around it either in bonds or lone pairs) so when an atom does not have 4 bonds it must have a lone pair or ...
Sun Nov 09, 2014 8:37 pm
Forum: Hybridization
Topic: Fall 2011 Midterm 6C and fall 2012 midterm 6A
Replies: 3
Views: 551

### Re: Fall 2011 Midterm 6C and fall 2012 midterm 6A

The hybridization is determined by the number of regions of high electron density. Each bond (single, double, or triple) and each electron pair (or even a single electron if it is unpaired) is a region of high electron density. 2 regions= sp 3 regions= sp2 4 regions= sp3 5 regions= sp3d 6 regions= s...
Sun Nov 02, 2014 9:07 pm
Forum: Electronegativity
Topic: Electronegativity influencing solubility
Replies: 1
Views: 11208

### Re: Electronegativity influencing solubility

The rule is "like dissolves like." So since water is a polar molecule, it dissolves polar compounds, and the more polar a compound is the more soluble it is in water. To determine which compound of the two in each part is more polar you use electronegativity. The compound with the greatest...
Sun Oct 26, 2014 7:49 pm
Forum: Lewis Structures
Topic: Lewis Structure of ONF
Replies: 1
Views: 1432

### Re: Lewis Structure of ONF

Fluorine has 7 valence electrons so it only needs one more to complete its octet (also note that F is in period 2 and only elements in period 3 or higher can have an expanded valence shell since those elements have d-orbitals). Thus, F will form only single bonds. O needs 2 electrons to complete its...
Sun Oct 19, 2014 10:06 pm
Forum: Empirical & Molecular Formulas
Topic: Combustion and Solving for Empirical and Molecular Formula
Replies: 1
Views: 293

### Combustion and Solving for Empirical and Molecular Formula

#1 of Quiz 1 Preparation Fall 2012 says that a compound containing carbon, hydrogen, and oxygen undergoes complete combustion. It looks like the answer assumes that all of the oxygen in the products (CO2 and H2O) came from the compound, but combustion always has O2 as a reactant so some of the oxyge...
Sun Oct 19, 2014 9:51 pm
Forum: Limiting Reactant Calculations
Replies: 2
Views: 571