## Search found 24 matches

Tue Mar 08, 2016 9:54 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: cis conformation
Replies: 2
Views: 402

### Re: cis conformation

I believe trans would be one substituent on axial and the other on equatorial. As for cis, the more stable confirmation would be if the larger substituents were both on the equatorial axis.
Mon Feb 29, 2016 5:38 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Dashes in Naming
Replies: 1
Views: 300

### Dashes in Naming

For the last example on page 106 of the course reader, why are there dashes in between bromo-chloro-propene? Why isn't the answer just E-1,1-bromochloropropene? I thought dashes are only used when switching between numbers and letters.

Thank you!
Fri Feb 26, 2016 8:48 am
Forum: *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
Topic: Equivalent H
Replies: 2
Views: 506

### Re: Equivalent H

Also, in the example above the carbons can be considered equivalent as well.
Thu Feb 18, 2016 12:28 am
Forum: First Order Reactions
Topic: Rate Law Units
Replies: 1
Views: 415

### Rate Law Units

For first-order rate law constants, does the units need to be in s-1 or min-1?
The solutions guide for 15.29 part a lists the rate constant as 0.17min instead of in seconds.
Thank you!
Wed Feb 17, 2016 10:55 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Chapter 15 question 3c.
Replies: 2
Views: 543

### Re: Chapter 15 question 3c.

Basically, just divide the rate you got in part a by 2, because there are 2 moles of NO2 in the balanced equation.

6.5 x 10^-3M/s / 2 = 3.3 x 10^-3 M/s
Mon Feb 15, 2016 5:51 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Forward Reaction
Replies: 3
Views: 527

### Re: Forward Reaction

In addition, we can use some sort of mechanism to remove the product, so that we do not have to take the reverse reaction into consideration. Or, the product may be a gas, in which case the reverse reaction will not occur.
Mon Feb 15, 2016 5:50 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Calculating n and k from more than 3 reactions
Replies: 1
Views: 330

### Re: Calculating n and k from more than 3 reactions

Even if you are provided more than three reactions, you wouldn't require more than three to find k or n.
Sun Feb 07, 2016 6:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculate Standard Potential from Half Reaction
Replies: 1
Views: 532

### Calculate Standard Potential from Half Reaction

For HW 14.27, why is it that we need to convert the E0 values into deltaG0 values? Why isn't the answer simply -1.79V + (-0.61V)? Question: 14.27 Using data in Appendix 2B, calculate the standard potential for the half-reaction U4+(aq) + 4e- --> U(s). The half reactions I used are U3+ + 3e- --> U E0...
Thu Feb 04, 2016 4:59 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Electrolytic vs. Galvanic Cells
Replies: 1
Views: 376

### Re: Electrolytic vs. Galvanic Cells

Galvanic cells release energy, so they are exothermic. Gibbs free energy is negative, so the reaction is spontaneous. The cell potential difference is positive. E0 is positive. Electrolytic cells require energy, so they are endothermic. Gibbs free energy is positive, so the reaction is not spontaneo...
Tue Jan 26, 2016 3:32 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Which is "more ordered"? (9.37)
Replies: 1
Views: 574

### Which is "more ordered"? (9.37)

For HW 9.37 part d, the answer key says the 4 moles of solid products are more ordered than the 4 moles of solid reactants. The reaction is 4KCLO3(s) --> 3KCLO4(s) + KCL(s). Why is this the case?
Sat Jan 23, 2016 6:49 pm
Forum: Phase Changes & Related Calculations
Topic: Thermochemistry vs. Thermodynamics
Replies: 1
Views: 914

### Re: Thermochemistry vs. Thermodynamics

Thermochemistry is a branch of thermodynamics.
Thermodynamics is the overall study of heat conversions (and other energy forms), while thermochemistry is specifically the study of thermodynamics in regards to chemical reactions.
Sat Jan 23, 2016 6:45 pm
Forum: Calculating Work of Expansion
Topic: Unit Conversions
Replies: 2
Views: 368

### Re: Unit Conversions

Multiplying by 101.325J/L atm is basically the same thing as using the gas constants and converting to Joules.
Fri Jan 15, 2016 11:24 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity of a Monoatomic Ideal Gas (9.13)
Replies: 7
Views: 1013

### Heat Capacity of a Monoatomic Ideal Gas (9.13)

If the heat capacity of a monoatomic ideal gas is Cp = 5/2 R, then for question 9.13, why don't we use this value, as used in 9.7 for part a? Similarly, why is the Cv = 3/2 R value for monoatomic ideal gas used for 9.7, and not for 9.13?
Sat Jan 09, 2016 8:12 pm
Forum: Phase Changes & Related Calculations
Topic: Conditions for Standard Enthalpy
Replies: 1
Views: 276

### Re: Conditions for Standard Enthalpy

If I understand your question correctly, the "condition" for volume in terms of enthalpy of a reaction is simply that the reaction must occur at a constant volume. As a result, we can say that the enthalpy of a reaction is the same as the change in internal energy.
Thu Nov 26, 2015 11:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Video: Polar vs. Nonpolar?
Replies: 1
Views: 349

### Video: Polar vs. Nonpolar?

This video explains how to determine if a compound is polar or nonpolar. I hope you like it!
Wed Nov 18, 2015 9:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Thermodynamic Stability
Replies: 1
Views: 275

### Thermodynamic Stability

Hi,

What does it mean to be thermodynamically more stable? My question refers to part c of 11.45, which asks if Cl2 or F2 is more stable, based on their concentrations at 1000K.

Thank you!
Sun Nov 15, 2015 2:20 pm
Forum: Ideal Gases
Topic: Online Interactive Module
Replies: 1
Views: 479

### Online Interactive Module

This online interactive module illustrates different principles regarding PV=nRT.

http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::100%::100%::/sites/dl/free/0023654666/117354/Ideal_Nav.swf::Ideal%20Gas%20Law%20Simulation
Tue Nov 03, 2015 6:13 pm
Forum: Hybridization
Topic: Hybridization of Lone Pair
Replies: 1
Views: 468

### Hybridization of Lone Pair

Hi, I have a question about identifying the hybridization of lone pairs in the structure CH2=CHCHO (question six of 2010 midterm). Are we supposed to simply look at the hybridization for the atom by treating the lone pairs as regions of electron density?
Tue Oct 27, 2015 10:14 pm
Forum: Ionic & Covalent Bonds
Topic: 3.79
Replies: 1
Views: 552

### 3.79

Hi, I have a question about 3.79. The question says: "Compounds having bonds with a high covalent character tend to be less soluble in water than similar compounds that have low covalent character. Use ekectonhgatives to predict which of the following compounds is the more soluble in water: (a)...
Fri Oct 23, 2015 11:45 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: How to distinguish between bonding/antibonding orbitals
Replies: 1
Views: 365

### Re: How to distinguish between bonding/antibonding orbitals

Hi, As for bonding and antibonding orbitals, look at the electron density. For bonding orbitals, there is an increase in electron density between the nuclei. For antibonding orbitals, there is a decrease in electron density. Also, electrons in the bonding orbitals stabilize the molecules more than e...
Fri Oct 16, 2015 4:22 pm
Forum: Lewis Structures
Topic: Various Lewis Structures
Replies: 2
Views: 361

### Re: Various Lewis Structures

Generally speaking, the more "correct" Lewis dot structures have minimal formal charges. (Minimal formal charge = more stable)
Fri Oct 16, 2015 4:14 pm
Forum: Ionic & Covalent Bonds
Topic: Diatomic Molecules
Replies: 3
Views: 489

### Re: Diatomic Molecules

To help remember the diatomic molecules, try "brinclhof."
Br, I, N, Cl, H, O, F
Sat Oct 10, 2015 1:53 pm
Forum: *Shrodinger Equation
Topic: Wave Function
Replies: 3
Views: 659

### Re: Wave Function

Hi, Think of wave functions as a physics concept and orbitals as a chemistry concept. Wave functions are equations that describe the quantum state of a particle. In other words, a wave function is a math function that represents the possible states of a system of particles. Orbitals are wave functio...
Thu Oct 01, 2015 9:16 pm
Forum: Empirical & Molecular Formulas
Topic: F.21
Replies: 5
Views: 1367

### F.21

Hi, I have a question about number 21 in the F section of the Fundamental Problems. Q: In 1978, scientists extracted a compound with antitumor and antiviral properties from marine animals in the Caribbean Sea. A sample of the compound didemnin-A of mass 1.78 mg was analyzed and found to have the fol...