Search found 53 matches
- Sat Mar 17, 2018 2:35 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
Q: Why do chemists like nitrates so much? A: They're cheaper than day rates.
- Sat Mar 17, 2018 2:34 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
Q: Why do chemists call helium, curium, and barium the healing elements? A: Because if you can't helium or curium, you barium!
- Sat Mar 17, 2018 2:33 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
Q: What do you call Iron blowing in the wind? A: Febreeze.
- Sun Mar 11, 2018 5:59 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
Physical chemistry: the pitiful attempt to apply y=mx+b to everything in the universe
- Sun Mar 11, 2018 5:55 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
Why do chemistry professors like to teach about ammonia?
Because it's basic material.
Because it's basic material.
- Sun Mar 11, 2018 5:53 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
Heisenberg is out for a drive when he's stopped by a traffic cop.
The cop says: " Do you know how fast you were going?"
Heisenberg replies: "No, but I know where I am".
The cop says: " Do you know how fast you were going?"
Heisenberg replies: "No, but I know where I am".
- Mon Mar 05, 2018 12:09 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
In a sports relay race, a chemical kinetics specialist runs slowly, and his group loses the race.
When the chemical kinetics specialist is asked why he ran slowly, his reply was “I always wanted to be the significant rate determining step”.
When the chemical kinetics specialist is asked why he ran slowly, his reply was “I always wanted to be the significant rate determining step”.
- Mon Mar 05, 2018 12:06 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: slowest step determines rate of overall reaction
- Replies: 3
- Views: 557
slowest step determines rate of overall reaction
could someone explain why the slowest step in a rate reaction determines the overall rate of the reaction. thanks!
- Mon Mar 05, 2018 12:05 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: rate order vs contribution to overall rate
- Replies: 3
- Views: 540
rate order vs contribution to overall rate
I was wondering which rate order correlates to the fastest rate, or is there no correlation. For example is a reaction that is first order always faster/slower than a rate at second order if all other variables remain the same?
- Tue Feb 20, 2018 9:37 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 14.41 (b)
- Replies: 2
- Views: 404
Re: 14.41 (b)
I had a similar problem when calculating this problem I got n=2 because the balanced equation is H2=2H+ +2e but the solution manual said n=1
- Tue Feb 20, 2018 9:34 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.15a
- Replies: 4
- Views: 538
Re: 14.15a
Also why in the solutions manual does it have AgBr before Br- in the galvanic cell. I thought since it was an anode Br- should go first since it has more electrons and is thus oxidized
- Tue Feb 20, 2018 9:33 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.15a
- Replies: 4
- Views: 538
Re: 14.15a
Also why in the solutions manual does it have AgBr before Br- in the galvanic cell. I thought since it was an anode Br- should go first since it has more electrons and is thus oxidized
- Sun Feb 18, 2018 11:18 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
Two men walk into a restaurant. The First man orders, "I'd like H2O". The second man orders, "I'd like H2O too". The second man died.
- Sun Feb 18, 2018 11:15 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
Why was the electrochemical cell arrested?
Because he was convicted of battery.
Because he was convicted of battery.
- Tue Feb 13, 2018 11:12 pm
- Forum: Calculating Work of Expansion
- Topic: Formulas for monatomic vs diatomic gases
- Replies: 2
- Views: 547
Re: Formulas for monatomic vs diatomic gases
Those are the formulas for constant volume, if asked for constant pressure add R to those values. This would give you Cp(monatomic)=5/2R and Cp(diatomic)=7/2R
- Sun Feb 11, 2018 8:17 pm
- Forum: Phase Changes & Related Calculations
- Topic: calculating a phase change in a reaction
- Replies: 5
- Views: 785
calculating a phase change in a reaction
This is somewhat of a broad question that I am not entirely sure how to phrase correctly. In some instances with calculations involving reactions it is necessary to include when a solid or liquid changes to a gas if the product it forms is also a gas, but sometimes you don't. When do you know when t...
- Sun Feb 11, 2018 8:13 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Isothermal expanision and deltaU [ENDORSED]
- Replies: 2
- Views: 374
Isothermal expanision and deltaU [ENDORSED]
Why is it that when there is an isothermal expanison, and thus deltaT=0, that deltaU also equals 0?
- Sun Feb 11, 2018 3:04 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy and spontaneity
- Replies: 3
- Views: 474
Gibbs free energy and spontaneity
Is calculating G the only way to officially conclude spontaneity? Because based on the equation calculating merely entropy or enthalpy doesn't appear to be enough.
- Wed Jan 31, 2018 1:08 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: example 9.16 [ENDORSED]
- Replies: 1
- Views: 276
example 9.16 [ENDORSED]
the question asks you to estimate the temperature at which it is thermodynamically possible for a reaction to occur. In the explanation it says when temp is increased there is a point where T= standardH/standardS. However in order for this to be true following the equation StandardG=StandardH-Tstand...
- Tue Jan 30, 2018 11:37 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: G=H-TS
- Replies: 4
- Views: 814
G=H-TS
The book says that the higher the temperature the less positive the Gibbs free energy, but isn't that not 100% correct? Looking at the formula G=H-TS if H is positive and S is negative then a higher temperature would actually result in a higher value of G
- Tue Jan 30, 2018 11:31 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy of reaction vs. standard Gibbs free energy of reaction
- Replies: 2
- Views: 540
Gibbs free energy of reaction vs. standard Gibbs free energy of reaction
Can someone explain what the textbook means when it says the standard Gibbs free energy of reaction is the difference between pure products and reactants, and therefore doesn't change over the course of a reaction as opposed to Gibbs free energy of reaction which does change over the course of a rea...
- Sun Jan 28, 2018 10:14 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: example 9.2
- Replies: 2
- Views: 342
example 9.2
The example asks you to find the change in entropy when a gas is heated at a constant volume. You have to use the equation deltaS=C ln(T2/T1), but I was wondering why you don't have to account for a change in pressure... or is there no change in pressure?
- Wed Jan 24, 2018 12:00 am
- Forum: Administrative Questions and Class Announcements
- Topic: Equations and constants sheet 14B
- Replies: 2
- Views: 538
Re: Equations and constants sheet 14B
is that because you have to cube the decimeter? because I am still confused as why everywhere I look online it says 1L=.001 cubic meters
- Tue Jan 23, 2018 11:22 pm
- Forum: Phase Changes & Related Calculations
- Topic: Names of phase changes
- Replies: 4
- Views: 482
Names of phase changes
I know the names of the endothermic phase changes (vaporization fusion and sublimation), but what are the names of their exothermic counterparts?
- Tue Jan 23, 2018 11:14 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Equations and constants sheet 14B
- Replies: 2
- Views: 538
Equations and constants sheet 14B
On the equations and constants sheet it says 1L=1dm^3 does the d mean deci?, because when I googled it it said 1L=.001 cubic meters.
- Tue Jan 23, 2018 12:01 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: q isn't a state function
- Replies: 3
- Views: 3602
q isn't a state function
In a review session we were going over things that were and were not state functions. What came up was q and w were not state functions. I understand work but could someone give an example as to why heat isn't a state function.
- Fri Jan 19, 2018 11:22 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: W=-(Pex)(deltaV)
- Replies: 5
- Views: 1555
W=-(Pex)(deltaV)
Can someone explain what the negative sign means on this equation?
- Tue Jan 16, 2018 11:24 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: molar heat capacity of a monatomic ideal gas
- Replies: 1
- Views: 334
molar heat capacity of a monatomic ideal gas
Do we need to memorize the molar heat capacities of monatomic ideal gasses, specifically the values given for atoms, linear molecules and nonlinear molecules?
- Tue Jan 16, 2018 10:09 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.57
- Replies: 2
- Views: 294
8.57
I am extremely confused on how to approach this problem. Can someone please explain to me what clue in the problem allowed them to realize they had to write combustion equations for the individual components of the given equation.
- Sun Jan 14, 2018 9:43 pm
- Forum: Phase Changes & Related Calculations
- Topic: enthalpy definition
- Replies: 3
- Views: 606
enthalpy definition
What exactly is enthalpy? I know that it is extremely important in thermochemistry but I am still a little shaky as to what it exactly is.
- Sun Jan 14, 2018 9:40 pm
- Forum: Phase Changes & Related Calculations
- Topic: Open/Closed/Isolated
- Replies: 11
- Views: 1176
Re: Open/Closed/Isolated
what actually constitutes the difference between an open and closed system?
- Sun Jan 14, 2018 9:35 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: molar heat capacity of a gas
- Replies: 1
- Views: 162
molar heat capacity of a gas
Why do gasses have two different values for the molar heat capacity as opposed to solids and liquids only having one?
- Sun Dec 10, 2017 3:15 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Memorizing
- Replies: 3
- Views: 598
Re: Memorizing
A little off topic but don't forget Copper and Chromium are exceptions for electron configuration
- Sun Dec 10, 2017 3:13 pm
- Forum: Coordinate Covalent Bonds
- Topic: transition metals
- Replies: 3
- Views: 1146
Re: transition metals
I think what you are referring to is the oxidation state. In which case you look at the charge of all the individual items attached to the metal. For example Cl has a -1 charge. Then you look at the overall charge of the compound. The oxidation state is the number that allows for the individual comp...
- Sun Dec 10, 2017 3:09 pm
- Forum: Biological Examples
- Topic: Hemoglobin
- Replies: 5
- Views: 1061
Re: Hemoglobin
I am unsure of the coordination compound but the transition metal is iron
- Sun Dec 10, 2017 3:08 pm
- Forum: Lewis Structures
- Topic: SO2
- Replies: 5
- Views: 829
Re: SO2
If you apply two double bonds none of the atoms will have a charge since sulfur can have two unpaired electrons due to its expanded octet
- Tue Dec 05, 2017 9:14 pm
- Forum: Bronsted Acids & Bases
- Topic: Net ionic equations (12.9)
- Replies: 1
- Views: 224
Re: Net ionic equations (12.9)
I was also unsure of this problem. If it weren't stated in the problem would there be any way to infer these compounds are ionic?
- Tue Dec 05, 2017 8:29 pm
- Forum: Conjugate Acids & Bases
- Topic: 12.1
- Replies: 4
- Views: 819
Re: 12.1
I am confused about part b. It is asking for the conjugate acid of NH2NH2. Both nitrogens have a lone pair, so could the hydrogen from H2O attach to either one?
- Wed Nov 29, 2017 11:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 4.81 [ENDORSED]
- Replies: 1
- Views: 352
4.81 [ENDORSED]
4.81 is asking for the Lewis structure of the borazine (B3N3H6). the boron and nitrogen molecules alternate to form a hexagon core where each one is also attached to one hydrogen. In the solutions manual it has a double bond for every other bond in the hexagon. However, this means the nitrogen have ...
- Tue Nov 28, 2017 4:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solids and liquids
- Replies: 1
- Views: 830
Solids and liquids
Why exactly aren't solids and liquids included in the equation to determine K. I vaguely remember in lecture Professor Lavelle touched on the point that they don't change in concentration, but what does that have to do with them being omitted from the equation.
- Tue Nov 28, 2017 3:58 pm
- Forum: Naming
- Topic: Naming polydentates
- Replies: 1
- Views: 214
Naming polydentates
If a ligand can function both as a polydentate and a monodenate, when naming it would you use the greek prefixes (bis, tris, etc.)?
- Wed Nov 15, 2017 12:56 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
A photon checks into a hotel. The manager at the front desks asks if he will be needing any help with luggage. The photon replies "no thank you I'm traveling light."
- Wed Nov 15, 2017 12:47 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shape vs. Electron Arrangement
- Replies: 2
- Views: 302
Re: Shape vs. Electron Arrangement
I'm not sure if this helps that much but when determining the shape of a molecule it is helpful to first plot out its electron arrangement to serve as a starting point. From the electron arrangement you can infer the shape.
- Thu Nov 09, 2017 3:07 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: HW 3.83
- Replies: 7
- Views: 3153
Re: HW 3.83
yes that is correct. I was a little confused with this problem as well. Originally I put Br->Cl->N3->O2 because I thought this described the trend of largest anion radius to smallest. Why are does oxygen go before nitrogen?
- Thu Nov 09, 2017 2:30 pm
- Forum: Electronegativity
- Topic: problem 3.75
- Replies: 1
- Views: 369
problem 3.75
This textbook question asks for trends in electropositivity for the first two groups of the periodic table. In the solutions manual it gives a list of the elements in order of increasing electropositivity. Within the list it states that Beryllium is more electropositive (more willing to give up elec...
- Wed Nov 01, 2017 12:01 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
Q: What is the name of 007's Eskimo cousin?
A: Polar Bond.
A: Polar Bond.
- Thu Oct 26, 2017 8:49 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592757
Re: Post All Chemistry Jokes Here
Helium walks into a bar,
The bar tender says "We don't serve noble gasses in here."
Helium doesn't react.
The bar tender says "We don't serve noble gasses in here."
Helium doesn't react.
- Tue Oct 17, 2017 8:37 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectroscopy Conceptually
- Replies: 3
- Views: 365
Atomic Spectroscopy Conceptually
I am having a little trouble imagining what exactly happens to an electron when it is excited and moves up an energy level. An electron revolves around the nucleus in somewhat of an unpredictable way so when it is excited where exactly does it go? Does it move farther away from the nucleus?
- Tue Oct 17, 2017 5:26 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem 14A website password
- Replies: 1
- Views: 328
Chem 14A website password
I enrolled into the class late and was never formally emailed the password to the website. Someone had given it to me but I seem to have forgot it. Is there any way someone could send it to me?
- Thu Oct 12, 2017 12:18 am
- Forum: Photoelectric Effect
- Topic: Figure 1.19
- Replies: 1
- Views: 198
Figure 1.19
In figure 1.19 on page 15 of the textbook an illustration depicting an experiment is shown. Waves of electromagnetic radiation are shot at a screen and pass through a pair of closely spaced slits, and as a result circular waves are generated on the other side of the screen. This figure is used to de...
- Tue Oct 10, 2017 9:19 pm
- Forum: *Black Body Radiation
- Topic: Wien's law [tex]\lambda max[/tex] [ENDORSED]
- Replies: 1
- Views: 504
Wien's law [tex]\lambda max[/tex] [ENDORSED]
Hello everyone,
I know lambda is what is used to represent wavelength however in Wien's law it represents intensity. To my knowledge these are completely different things, so is lambda used to represent both, or is intensity and wavelength related?
I know lambda is what is used to represent wavelength however in Wien's law it represents intensity. To my knowledge these are completely different things, so is lambda used to represent both, or is intensity and wavelength related?
- Sun Oct 08, 2017 8:01 pm
- Forum: Significant Figures
- Topic: All students read this sig fig post [ENDORSED]
- Replies: 170
- Views: 34557
Re: All students read this sig fig post [ENDORSED]
On the test on 10/6/17, I had trouble allotting enough time to answer all the questions and I believe it was mostly as a result of me taking my time thinking about what significant figures I should be using throughout my intermittent calculations. Are significant figures a crucial part to the test ...
- Thu Oct 05, 2017 9:37 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Chemistry Community posts
- Replies: 1
- Views: 438
Chemistry Community posts
This is sort of a general question more about the course, but does anyone know when the cycle for the two posts on chemistry community resets in terms of getting points?