## Search found 26 matches

Sat Mar 12, 2016 5:53 pm
Forum: *Aldehydes
Topic: Specific molecules
Replies: 1
Views: 655

### Specific molecules

Will we be expected to know the function of different organic compounds (whether they are used as fuels, pesticides, etc), including but not limited to specific aldehydes?
Fri Mar 11, 2016 12:26 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrolytes
Replies: 1
Views: 270

### Electrolytes

For the galvanic cells, I noticed that in some cells (the Daniell cell), two electrolytes of CuSO4 and ZnSO4 are used, but in some cases, the anode and cathode share an electrolyte. Is there any reason why one would use two different electrolytes/ in which cases can this be noted?
Fri Mar 11, 2016 12:22 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW Question 8.89
Replies: 2
Views: 959

### Re: HW Question 8.89

I think I may have solved part of it, but my significant figures were off. I solved it as such: Since enthalpy is a state function, I assumed that to be able to get to the enthalpy of sublimation (formation of the gas), one would use the enthalpy of fusion + the enthalpy of vaporization. The enthalp...
Tue Mar 08, 2016 3:46 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.117
Replies: 2
Views: 515

### Re: 8.117

Does it not matter that the equation is not balanced for the O's?
Tue Mar 08, 2016 1:55 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW Question 8.89
Replies: 2
Views: 959

### HW Question 8.89

The heat capacity of liquid iodine is 80.7 J/K per mol and the enthalpy of vaporization of iodine is 41.96 kJ/mol at its boiling point of 184.3 degrees Celsius. Calculate the enthalpy of fusion of iodine at 25 degrees Celsius. I was not sure how to approach the problem and which formulas to use to f...
Sun Mar 06, 2016 1:16 am
Forum: Administrative Questions and Class Announcements
Topic: Video Competition
Replies: 66
Views: 25028

### Re: Video Competition

Since there has been an error message, both with uploading on chemistry community and on youtube for the past 2 hours or so with my account, I am reposting the link here in case it did not work the first time. Shweta Chawla, Megan Ren (Lecture 2) Video on Integration and Application to Rate Laws htt...
Sun Mar 06, 2016 12:00 am
Forum: Administrative Questions and Class Announcements
Topic: Video Competition
Replies: 66
Views: 25028

### Re: Video Competition

Shweta Chawla and Megan Ren (Lecture 2)

Video on Integration and Application to Rate Laws

Tue Mar 01, 2016 2:17 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Electrophilic Aromatic Substitution
Replies: 1
Views: 367

### Electrophilic Aromatic Substitution

For an electrophilic aromatic substitution, does an increased amount of base decrease the rate of reaction? Intuitively, I would guess that in the rate-determining step, an increased amount of base would decrease the likelihood of the E+ bonding with the aromatic structure, but also noticed that in ...
Tue Mar 01, 2016 2:14 am
Forum: *Alkenes
Topic: Structural Formulas
Replies: 1
Views: 411

### Structural Formulas

For 2-methyl - 2-butene, why would the structural formula be (CH3)2CCHCH3 instead of CH3C(CH3)CHCH3?
When can we combine groups like that, and would the second structural formula still be acceptable?
Sun Feb 21, 2016 4:18 pm
Forum: General Rate Laws
Topic: Rate Laws
Replies: 1
Views: 297

### Re: Rate Laws

The rate law would have the same structure, with the half orders as exponents; thus the exponents would be fractions.
Tue Feb 09, 2016 2:04 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: The state (gr)
Replies: 1
Views: 1797

### The state (gr)

In 14.11 example (b), what does C (gr) mean?
Fri Jan 29, 2016 11:42 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Residual Molar Entropy
Replies: 3
Views: 506

### Residual Molar Entropy

For residual molar entropy, specifically for organic molecules, how can we determine the structure, due to the number of isomers and the subsequent number of positions for each isomer?
Fri Jan 29, 2016 11:36 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Intensive propery
Replies: 1
Views: 327

### Re: Intensive propery

This means that the number of moles will not affect the reduction potential; it will be constant.
Wed Jan 20, 2016 8:14 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.35B
Replies: 1
Views: 400

### 8.35B

The high-temperature contribution of vibrational modes to the molar heat capacity for a solid at constant volume is R for each mode of vibrational motion. For a monatomic solid it is ~ 3R. A) The specific heat capacity of a certain monatomic solid is 0.392 J/K x g; the chloride of the element (XCl2)...
Mon Jan 18, 2016 3:23 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Enthalpy in a System
Replies: 2
Views: 485

### Re: Enthalpy in a System

The total enthalpy must be conserved, so energy lost by the system/gained by the system is then absorbed by the surroundings/is from energy released from the surroundings, leading the final value to be a constant, in this case 0.
Sun Jan 10, 2016 3:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: bond enthalpies
Replies: 2
Views: 378

### Re: bond enthalpies

When the "product" molecule is formed, it tends to exist in a more stable state than the initial reactant molecules, thus containing less energy. The difference between the energy of the initial reactant molecules and this final product results in energy being released, leading this proces...
Fri Dec 04, 2015 12:52 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Determining pH given 2 Ka Values
Replies: 2
Views: 9239

### Re: Determining pH given 2 Ka Values

According to Chem_Mod's previous responses, this is a concept we will later learn. Is it possible to do by the calculation of H+ concentrations? I did it multiple times and got a pH of 1.30.
Thu Nov 26, 2015 1:24 am
Forum: Biological Examples
Topic: Carbonate Diagram
Replies: 1
Views: 596

### Carbonate Diagram

Is there a useful diagram/picture that could help demonstrate how carbonate can be both monodentate and bidentate? Are there any ligands that can be both?
Thu Nov 26, 2015 1:18 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Endothermic and Exothermic Reactions
Replies: 3
Views: 716

### Re: Endothermic and Exothermic Reactions

The enthalpies are almost often included when they ask about the reaction. If this is not the case, knowledge about which molecules are the most stable in the reaction could help understand whether it is endothermic or exothermic, because the energy is often put in to break these apart, or released ...
Wed Nov 18, 2015 2:16 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentrations
Replies: 1
Views: 345

### Concentrations

Is there a mathematical example to show that final equilibrium concentrations of [O2]/[O3] would be different when starting with different initial concentrations of each, while K, which depends on the expression [O2]^3/[O3]^2 is constant? (Problem 11.11 part C)
Fri Nov 13, 2015 11:03 pm
Forum: Biological Examples
Topic: Biological Compounds: Balance
Replies: 1
Views: 382

### Biological Compounds: Balance

Are there specific metals which are biologically important to our body in small amounts, but in excess can be toxic? What are some examples?
Fri Oct 30, 2015 3:31 am
Forum: Hybridization
Topic: Hybridized vs. Unhybridized
Replies: 1
Views: 360

### Re: Hybridized vs. Unhybridized

To create any sort of hybrid orbital, a lower energy orbital must be combined with a higher one in order to form molecular orbitals of intermediate energy. As there is no orbital lower than the "s" orbitals, it seems as though these will always be involved in hybrid orbital formation.
Thu Oct 22, 2015 9:22 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Increased Angle
Replies: 1
Views: 381

### Increased Angle

Lone pairs of electrons often lead to a smaller angle between bonds. What situations could lead to a larger one?
Thu Oct 08, 2015 1:41 am
Topic: Black Body Prediction with Classical Physics [ENDORSED]
Replies: 1
Views: 542

### Black Body Prediction with Classical Physics[ENDORSED]

In the book, it stated that if adhering to the rules of classical physics, the blackbody would be expected to emit ultraviolet light even at low temperatures. Can someone explain how this would make sense and which formulas from classical physics are being used?
Thu Oct 01, 2015 8:33 pm
Forum: Empirical & Molecular Formulas
Topic: Oxygen in Chemical Formulas
Replies: 2
Views: 474

### Oxygen in Chemical Formulas

How do you know if oxygen is in the original compound or was only added as a reactant for combustion when asked for the original empirical formula? Referring specifically to M.21 in the 6th edition.
Thu Oct 01, 2015 2:01 am
Forum: Significant Figures
Topic: Use of Significant Figures with Constants
Replies: 3
Views: 9998

### Use of Significant Figures with Constants

When using constants such as Planck's constant, if Planck's constant is specified in the problem, does it count as a number which could affect the final number of significant figures? If it is not specified, do we just use the smallest number of significant figures already specified in the problem o...