Search found 51 matches
- Sat Mar 17, 2018 8:49 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3591242
Re: Post All Chemistry Jokes Here
I hope this posts properly lol
- Sat Mar 17, 2018 8:34 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Elementary steps
- Replies: 2
- Views: 563
Elementary steps
In elementary steps, how are we finding the order when we're writing the rate laws? Are they coming from the stoichiometric coefficients because these are elementary steps? Because I know that the order isn't related to the stoichiometric coefficient, but when doing the mechanism problems, that's wh...
- Sat Mar 17, 2018 8:28 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G units
- Replies: 3
- Views: 2971
Delta G units
In the equation ΔG° = -nFE° we end up with units of joules while with the equation ∆G°=-RTlnK, we end up with units of joules per mole. How is this possible, and is there a way for ΔG° = -nFE° to yield units joules/mole?
- Sun Mar 11, 2018 10:23 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3591242
Re: Post All Chemistry Jokes Here
Q: What's a cation?
A: An ion with paws-itive charge :)
-3He
A: An ion with paws-itive charge :)
-3He
- Sun Mar 11, 2018 10:19 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3591242
Re: Post All Chemistry Jokes Here
Are you a nucleophile?
Because all you seem to do is bring negativity into my life.
Because all you seem to do is bring negativity into my life.
- Sun Mar 11, 2018 10:12 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: SN2
- Replies: 2
- Views: 346
Re: SN2
A nucleophile is a species that donates an electron pair, like a Lewis base. They replace another species that is more electronegative than the central atom that the nucleophile is being bound to. The substitution process occurs bc the leaving group is taking electrons from the central atom, and the...
- Sun Mar 04, 2018 4:37 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Quiz 3
- Replies: 6
- Views: 853
Re: Quiz 3
I read on another question that the test would cover up to question #49 I believe... Can anyone clear this up? The only questions between 39 and 49 listed on the outline are #45 and #47, and those both cover reaction mechanisms. Lavelle said in lecture that we won't be covering reaction mechanisms ...
- Sun Mar 04, 2018 4:32 pm
- Forum: Second Order Reactions
- Topic: Linearization of a Second Order Reaction
- Replies: 3
- Views: 2433
Re: Linearization of a Second Order Reaction
The inverse is taken because we equate the rate to k[A]^2, and when we bring the terms over to one side, we are left with the inverse of [A].
(-1/a)*(d[A]/dt)=k[A]^2
at a=1:
(d[A]/[A]^2)=-k*dt
Integration leads to the inverse. We take the inverse because that's what it mathematically turns out to be.
(-1/a)*(d[A]/dt)=k[A]^2
at a=1:
(d[A]/[A]^2)=-k*dt
Integration leads to the inverse. We take the inverse because that's what it mathematically turns out to be.
- Sun Mar 04, 2018 4:23 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetics vs Thermodynamics
- Replies: 4
- Views: 647
Re: Kinetics vs Thermodynamics
It depends on what the reaction is dependent upon and based off of that, which pathway the reaction will take.The kinetic pathway is the easiest pathway. A kinetically controlled reaction will be faster and when compared to a thermodynamic pathway, the products are less stable. The activation energy...
- Tue Feb 27, 2018 8:45 pm
- Forum: Experimental Details
- Topic: Homework Problem 15.3 Part C
- Replies: 5
- Views: 1142
Homework Problem 15.3 Part C
Part C asks what the unique rate of the reaction is. What does unique rate of reaction mean?
- Sun Feb 25, 2018 6:20 pm
- Forum: General Rate Laws
- Topic: Negative Sign [ENDORSED]
- Replies: 7
- Views: 981
Re: Negative Sign [ENDORSED]
The negative sign is so that the rate of your reactants is positive. We want to work with positive reaction rates, so we use the negative sign to make the reactants rate positive. Without the negative sign, we'd end up with a negative value because the [R] is decreasing. The final concentration is s...
- Sun Feb 25, 2018 6:17 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: activation energy
- Replies: 4
- Views: 579
Re: activation energy
A high activation energy means that the reaction is going to be slower to occur. The reaction takes more energy to occur, and will thus have a slower rate.
- Sun Feb 25, 2018 6:14 pm
- Forum: Zero Order Reactions
- Topic: Relation to Reaction Stoichiometry?
- Replies: 2
- Views: 430
Re: Relation to Reaction Stoichiometry?
By reaction stoichiometry, do you mean the stoichiometric coefficients? If so, I don't believe they are related.
- Sun Feb 18, 2018 9:08 pm
- Forum: Balancing Redox Reactions
- Topic: "Rules"
- Replies: 7
- Views: 863
Re: "Rules"
I think it's that you start out balancing with water, and then use the hydroxide to balance the water.
- Sun Feb 18, 2018 9:02 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum electrodes
- Replies: 4
- Views: 572
Re: Platinum electrodes
Are there any cases where a platinum electrode cannot be used and a different one has to be used? If so, do we need to know that for the purposes of this class?
- Sun Feb 18, 2018 9:00 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Order in Cell Diagrams
- Replies: 4
- Views: 570
Re: Order in Cell Diagrams
As long as you put the reactant first and the product second, the order of phases should line up
- Sun Feb 11, 2018 10:26 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isothermic
- Replies: 4
- Views: 679
Re: Isothermic
What is meant by constant measures?
- Sun Feb 11, 2018 10:25 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Oxidation
- Replies: 4
- Views: 397
Re: Oxidation
You can also use "an ox" and "red cat" to help you remember that an anode is oxidized and a cathode is reduced.
- Sun Feb 11, 2018 10:22 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible vs Irreversible
- Replies: 2
- Views: 415
Re: Reversible vs Irreversible
They differ because you're taking the area under curve, and the area's are each different and have different equations. Lavelle has a detailed diagram on his website showing this. It's under the lecture outlines.
- Sun Feb 04, 2018 7:07 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Test Number 1
- Replies: 9
- Views: 1082
Re: Test Number 1
So the heat was transferred to make up for the change in energy in the system?
- Sun Feb 04, 2018 6:58 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3591242
Re: Post All Chemistry Jokes Here
Fun fact: Josiah Gibbs was a Swiftie.
Haters gonna hate Taylor Swift=> ΔG=ΔH−TΔS
Haters gonna hate Taylor Swift=> ΔG=ΔH−TΔS
- Sun Feb 04, 2018 6:54 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Heat transfer
- Replies: 7
- Views: 873
Re: Heat transfer
Heat was being transferred to make up for the energy change.
- Sun Jan 28, 2018 9:31 pm
- Forum: Calculating Work of Expansion
- Topic: work done on and by the system
- Replies: 12
- Views: 1429
Re: work done on and by the system
When given a word problem, how can we tell that work is being done on the system or by the system?
- Sun Jan 28, 2018 9:24 pm
- Forum: Phase Changes & Related Calculations
- Topic: Superheating
- Replies: 6
- Views: 3361
Re: Superheating
Are there any other examples of superheating besides the microwave one?
- Sun Jan 28, 2018 9:19 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Difference between systems? [ENDORSED]
- Replies: 8
- Views: 1090
Re: Difference between systems? [ENDORSED]
Is a thermos still considered an isolated system if a person drinks from it?
- Sun Jan 21, 2018 8:00 pm
- Forum: Phase Changes & Related Calculations
- Topic: HW #3
- Replies: 3
- Views: 343
Re: HW #3
As long as you know the concepts behind the questions you should be fine.
- Sun Jan 21, 2018 7:46 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible vs Irreversible
- Replies: 4
- Views: 501
Re: Reversible vs Irreversible
Why is reversible work done so slowly?
- Sun Jan 21, 2018 7:40 pm
- Forum: Calculating Work of Expansion
- Topic: What do these variables mean?
- Replies: 4
- Views: 490
What do these variables mean?
I'm going through my notes and there was a line of reasoning of equations: w=FD; since F=PA then w=(PA)D=PΔV. I'm assuming that F represents force, D represents distance, and that A represents area, but I'm not too sure. The others I'm clear on. Can someone verify this for me? Thanks!
- Sun Jan 14, 2018 10:36 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Homework help on 8.29
- Replies: 4
- Views: 332
Re: Homework help on 8.29
Ah, so yes. Thinking in terms of number of bonds is incorrect. It's all about the potential to store energy then. That's cool.
- Sat Jan 13, 2018 7:08 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Homework help on 8.29
- Replies: 4
- Views: 332
Re: Homework help on 8.29
Your reasoning makes sense. NO2 is more molecularly complex than NO so it would have a higher molar heat capacity.
- Sat Jan 13, 2018 7:02 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: When considering enthalpy (Δ H=q), is the letter "H" or "ΔH" Enthalpy?
- Replies: 3
- Views: 435
Re: When considering enthalpy (Δ H=q), is the letter "H" or "ΔH" Enthalpy?
H is the symbol for enthalpy, while delta H represents the change in enthalpy. Enthalpy is the measure of the internal energy of the system and shows the thermodynamic potential of the system. Internal energy is also the energy required to create the system. Delta H/the change in enthalpy is used to...
- Fri Dec 08, 2017 5:36 pm
- Forum: Trends in The Periodic Table
- Topic: Smaller First Ionization Energy: Sr or Ru
- Replies: 1
- Views: 256
Re: Smaller First Ionization Energy: Sr or Ru
The experimentally calculated first ionization energy of Ru is approx 710 kJ/mol while the first ionization energy of Sr is approx 550 kJ/mol which does follow the periodic trend.
- Fri Dec 08, 2017 5:31 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Naming of Ligands
- Replies: 2
- Views: 252
Re: Naming of Ligands
A monodentate ligand means that the Lewis base can only donate one electron pair to the central metal atom, while bidentate means that two electron pairs are donated by the Lewis base, and tridentate means that three bonds are formed.
- Sun Dec 03, 2017 11:35 pm
- Forum: Bronsted Acids & Bases
- Topic: Is H+ a Bronsted acid?
- Replies: 1
- Views: 487
Re: Is H+ a Bronsted acid?
The hydrogen ion is the proton that can determine which molecule is a Brønsted acid or Brønsted base, but I don't think it itself is a Brønsted acid or base.
- Sun Dec 03, 2017 5:34 pm
- Forum: Bronsted Acids & Bases
- Topic: How do I identify if a molecule is a Bronsted Acid or Base?
- Replies: 5
- Views: 1677
Re: How do I identify if a molecule is a Bronsted Acid or Base?
In the balanced equation, check if the amount of hydrogens increased or decreased. If there was a decrease, that means that the molecule donated the protons (in the form of the hydrogen) and is then a Brønsted acid and if the amount of the hydrogens increased then the molecule accepted the protons a...
- Sun Nov 26, 2017 10:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs [ENDORSED]
- Replies: 3
- Views: 480
Re: Lone Pairs [ENDORSED]
No, only the lone pairs on the central atom affect the bonding angles since it is more electronegative.
- Sun Nov 26, 2017 10:19 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligands
- Replies: 2
- Views: 316
Re: Ligands
A ligand is an ion or neutral atom that bonds to a central metal atom. A ligand acts as a Lewis base meaning it donates an electron pair to the central atom. They bond through coordinate bonding.
- Tue Nov 14, 2017 5:48 pm
- Forum: Hybridization
- Topic: Relative Orientations (4.31)
- Replies: 1
- Views: 256
Re: Relative Orientations (4.31)
Relative orientation is the same as the VSEPR orientations for the non hybrid orbitals. Just determine them based on how many areas of electron density there are.
- Sun Nov 12, 2017 7:57 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Where to put the lone pairs?
- Replies: 3
- Views: 520
Re: Where to put the lone pairs?
What kind of trigonal do you mean? Planar or Bipyramidal?
- Sun Nov 12, 2017 4:07 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Textbook Problem Chp 4 #9
- Replies: 3
- Views: 440
Re: Textbook Problem Chp 4 #9
Trigonal planar is AX3 while the ICl3 molecule is AX3E2 which is what T- shaped is.
- Sun Nov 05, 2017 8:54 pm
- Forum: Lewis Structures
- Topic: Problem 3.59 Part A
- Replies: 4
- Views: 624
Re: Problem 3.59 Part A
Isn't ClO an anion?
- Sun Nov 05, 2017 8:52 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Lower in Energy? [ENDORSED]
- Replies: 6
- Views: 883
Re: Lower in Energy? [ENDORSED]
3d is higher in energy than 4s when the d orbital is empty. When 3d has an electron in it, 3d becomes lower in energy than 4s.
- Sun Oct 29, 2017 8:13 pm
- Forum: Lewis Structures
- Topic: Placement [ENDORSED]
- Replies: 6
- Views: 777
Re: Placement [ENDORSED]
The central atom is the one with the lowest ionization energy. Ionization energy increases from left to right and decreases from top to bottom. The central atom must be the one with the least ionization energy because it can form more bonds than the other element due to the lower ionization energy.
- Sun Oct 29, 2017 8:07 pm
- Forum: Ionic & Covalent Bonds
- Topic: Noble Gases
- Replies: 6
- Views: 889
Re: Noble Gases
The noble gasses still cannot bond with each other though, correct? Even under extreme circumstances?
- Sun Oct 22, 2017 9:28 pm
- Forum: Einstein Equation
- Topic: Comparing E=pc and E=.5mv^2
- Replies: 3
- Views: 637
Re: Comparing E=pc and E=.5mv^2
What information must be provided to determine which equation to use? Is it that E=pc can only be applied to a massless particle because the speed of light is for a massless particle/photon?
- Sun Oct 22, 2017 9:25 pm
- Forum: Properties of Light
- Topic: Velocity [ENDORSED]
- Replies: 13
- Views: 1624
Re: Velocity [ENDORSED]
The speed of light can be used as velocity for massless particles like photons. Not too sure about the whole relationship part.
- Sun Oct 15, 2017 11:04 pm
- Forum: Photoelectric Effect
- Topic: Determining the Series [ENDORSED]
- Replies: 3
- Views: 603
Re: Determining the Series [ENDORSED]
So when we're naming the series, do we name it from the lowest energy level? Like say the electron goes from n=3 to n=1. Would we name this as Paschen since that was the initial energy state in the problem, or do we name it as Lyman since n=1 is the lower state?
- Sun Oct 15, 2017 10:48 pm
- Forum: Properties of Light
- Topic: Concept // Wave-like Behavior [ENDORSED]
- Replies: 4
- Views: 497
Re: Concept // Wave-like Behavior [ENDORSED]
So, since the emission of electrons is not dependent on the level of intensity that the light is, will changing the wavelength effect its emission? I'm assuming the its refers to electrons. With that assumption, the changing of the wavelength will effect the emission of the electron. For the electr...
- Sun Oct 15, 2017 10:27 pm
- Forum: Properties of Light
- Topic: Electromagnetic Spectrum for Test
- Replies: 2
- Views: 366
Re: Electromagnetic Spectrum for Test
I'm not entirely sure about this, but it's most likely that if we need to know specifics, the series should be provided to us. In discussion we didn't go over the specifics so it should be provided if needed in the answer.
- Sun Oct 08, 2017 2:48 pm
- Forum: Significant Figures
- Topic: Whole Numbers, One Sig Fig [ENDORSED]
- Replies: 3
- Views: 650
Re: Whole Numbers, One Sig Fig [ENDORSED]
Hold up, sorry, the number 50 only has two sig figs if a decimal is in place, so you'd be fine with rounding down to 50. All though I'm not sure if you'd encounter a situation where there would only be one sig fig required to be in the answer.
- Sun Oct 08, 2017 2:44 pm
- Forum: Significant Figures
- Topic: Whole Numbers, One Sig Fig [ENDORSED]
- Replies: 3
- Views: 650
Re: Whole Numbers, One Sig Fig [ENDORSED]
The number 50 still has two sig figs, so instead you'd have to write the number 50 in scientific notation without the decimal point. So it would be written as 5 x 10^1.