Search found 31 matches
- Sat Mar 17, 2018 8:15 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Roomie Love <3
- Replies: 1
- Views: 493
Roomie Love <3
Just wanna thank my #1 fan, my snake roommate Nicole. She has supported me this entire year through thicc and thin.
- Mon Mar 12, 2018 10:40 pm
- Forum: General Rate Laws
- Topic: graphs
- Replies: 8
- Views: 981
Re: graphs
For the final I'm pretty sure we won't have to draw them ourselves, but we may be given a graph of one and have to figure out what order it is.
- Mon Mar 12, 2018 10:36 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: units
- Replies: 4
- Views: 762
Re: units
SI units and any conversions on the constants and equations sheet are fair game.
- Mon Mar 12, 2018 10:35 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetics Test Scores [ENDORSED]
- Replies: 3
- Views: 776
Re: Kinetics Test Scores [ENDORSED]
No you'll get the test back in discussion as usual.
- Tue Mar 06, 2018 11:51 am
- Forum: Zero Order Reactions
- Topic: Deriving Zero Order Half Life Equation
- Replies: 1
- Views: 367
Re: Deriving Zero Order Half Life Equation
Rate=−d[A]dt=k[A]0=k=constant
- Tue Mar 06, 2018 11:50 am
- Forum: General Rate Laws
- Topic: Molecularity vs Order
- Replies: 1
- Views: 261
Re: Molecularity vs Order
Molecularity is just the number of molecules that come together to form a reaction so I think there could be different molecularities for the elementary reactions and the overall reaction but probably not often. The order of a reaction depends on the pathway of the overall reaction so I would think ...
- Tue Mar 06, 2018 11:47 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Question about Test #3
- Replies: 2
- Views: 412
Re: Question about Test #3
I don't think there'll be anything past #45 because we just started elementary steps and so on on Monday.
- Mon Feb 26, 2018 8:33 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetics vs Thermodynamics
- Replies: 7
- Views: 1109
Re: Kinetics vs Thermodynamics
Kinetics deals with the rate of a reaction and thermodynamics deals with whether the reaction is favorable or not. A kinetically controlled reaction is one that does not occur because of a large activation energy barrier even though the products have a lower standard Gibbs free energy (i.e., the rea...
- Mon Feb 26, 2018 8:31 pm
- Forum: First Order Reactions
- Topic: Calculating slope
- Replies: 4
- Views: 696
Re: Calculating slope
It is also because, when graphed, the slope is negative (going to the right and down). So, for the slope to equal k, k must be negative as well.
- Mon Feb 26, 2018 8:27 pm
- Forum: General Rate Laws
- Topic: Homework Problem 15.3
- Replies: 4
- Views: 755
Re: Homework Problem 15.3
I think because the product also has a coefficient of two so it's a 1:1 ratio. Or maybe the concentrations given already factored that in.
- Mon Feb 19, 2018 8:37 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: 14.21
- Replies: 1
- Views: 365
Re: 14.21
Just remember that the anode half reaction is oxidized and the cathode half reaction is reduced. So, in part d, for the E of the cell to be positive (which it needs to be), the bigger positive E of either half reaction must go first in the equation (Ecell=Ecathode-Eanode). The bigger positive voltag...
- Mon Feb 19, 2018 8:33 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams [ENDORSED]
- Replies: 4
- Views: 21571
Re: Cell Diagrams [ENDORSED]
The anode half cell is described first, then the cathode half cell (so that as you read it, your eyes move in the direction of the electrons). Within a given half-cell, the reactants are specified first and the products last. A single vertical line is drawn between two chemical species that are in d...
- Mon Feb 19, 2018 8:28 pm
- Forum: Balancing Redox Reactions
- Topic: 14.15 part b
- Replies: 2
- Views: 438
Re: 14.15 part b
The cathode half reaction is O2 + 4H+ + 4e --> 2H2O. The anode half reaction is O2 + 2H2O + 4e --> 4OH-. So, to write the cell diagram, you have Pt on either side (think of the sides as almost symmetrical) and O2 on either side (inside the Pt), but the ions are H+ and OH- so since the H+ is in the c...
- Mon Feb 12, 2018 5:05 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Open System
- Replies: 5
- Views: 966
Re: Open System
An open system is also like a cup of coffee for example. You can exchange matter into or out of the system, like adding sugar to the coffee.
- Mon Feb 12, 2018 5:04 pm
- Forum: Calculating Work of Expansion
- Topic: Free Expansion
- Replies: 4
- Views: 675
Re: Free Expansion
They are conceptually a little different but yes, I think the variables you listed would all be zero for both.
- Mon Feb 12, 2018 5:01 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 2nd and 3rd law of Thermodynamics
- Replies: 2
- Views: 603
Re: 2nd and 3rd law of Thermodynamics
The second law of thermodynamics states the total entropy of the universe, an isolated system, can never decrease over time since energy can never be destroyed. The third law of thermodynamics states that the entropy of a perfect crystal at absolute zero, assuming it is at equilibrium, is exactly eq...
- Mon Feb 05, 2018 8:40 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacities of Dense Elements
- Replies: 2
- Views: 330
Re: Heat Capacities of Dense Elements
The kinetic, vibrational, rotational, and electronic energies of the particles determine the heat capacity of a system, so I would think (out of the three things you listed) that bond energies would matter the most in determining heat capacity.
- Mon Feb 05, 2018 8:34 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridges
- Replies: 2
- Views: 677
Re: Salt Bridges
Common salts to use include potassium chloride, sodium chloride, or potassium nitrate. The electrolytes chosen should not react with any of the chemicals used in the cell, and the anion and cation should have similar conductivity.
- Mon Feb 05, 2018 8:29 pm
- Forum: Balancing Redox Reactions
- Topic: Salt Bridges?
- Replies: 6
- Views: 651
Re: Salt Bridges?
The salt bridges maintain the neutrality in the two solutions. As electrons flow from the anode to cathode in the wire, the negatively charged ions migrate to the anode half cell using the salt bridges so that the solution in that half does not become positively charged, and vice versa for the catho...
- Tue Jan 30, 2018 8:41 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Entropy Change factors
- Replies: 6
- Views: 791
Re: Entropy Change factors
A more complex molecule has more possible positions it may attain (since there are more atoms involved) which is one way we measure entropy.
- Tue Jan 30, 2018 8:40 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Entropy vs. Standard Entropy
- Replies: 4
- Views: 543
Re: Entropy vs. Standard Entropy
Standard entropy specifically means that every reactant and product is in its purest state (i.e.: H2 gas) and that 1 mole of product is produced.
- Tue Jan 30, 2018 8:34 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Graph of G
- Replies: 2
- Views: 386
Re: Graph of G
Yes exactly, when G is negative (so when the slope on the graph was negative) the reaction is spontaneous. When G (or the slope) is positive, it is not spontaneous.
- Mon Jan 22, 2018 11:35 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Reaction Enthalpy
- Replies: 2
- Views: 341
Re: Reaction Enthalpy
Yeah pretty much, standard enthalpy of formation is assuming that everything is in its most stable form and there is one mole of product.
- Mon Jan 22, 2018 11:34 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Average Kinetic Energy
- Replies: 2
- Views: 369
Re: Average Kinetic Energy
I don't think so. I'd stick to the outline he gave.
- Mon Jan 22, 2018 11:33 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond enthalpies
- Replies: 1
- Views: 287
Re: Bond enthalpies
So when calculating standard enthalpy using bond enthalpies, the mean bond enthalpies provided will be for those bonds in the gaseous phase. In order to calculate the standard enthalpy of a reaction with something in a liquid or solid form, just use the bond enthalpies as you normally would then aft...
- Wed Jan 17, 2018 8:53 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.51
- Replies: 2
- Views: 314
Re: 8.51
When something is in its most stable form, the standard enthalpy of formation is zero because in a reaction it wouldn't change in any way to stabilize since it is already how it wants to be
- Wed Jan 17, 2018 8:46 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bong Enthalpy accuracy [ENDORSED]
- Replies: 3
- Views: 347
Re: Bong Enthalpy accuracy [ENDORSED]
Use whatever information is given to you, but yes Hess's Law is more accurate.
- Wed Jan 17, 2018 8:44 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.45
- Replies: 2
- Views: 215
Re: 8.45
The solutions manual probably just meant per mole of reaction. It's the same as just saying kj because it is implied that it it kj per mole of reaction.
- Fri Jan 12, 2018 12:17 am
- Forum: Bond Lengths & Energies
- Topic: Bond Order
- Replies: 6
- Views: 1149
Re: Bond Order
The bond order of CN is 2.5 because 0.5(7-2)=2.5. You subtract the nonbonding electrons from bonding electrons first, then divide by 2.
- Fri Jan 12, 2018 12:11 am
- Forum: Sigma & Pi Bonds
- Topic: delocalized pi bond
- Replies: 5
- Views: 2515
Re: delocalized pi bond
Delocalized bonds is when the electrons in the bond can move around so the bond can change, like in resonance structures.
- Fri Jan 12, 2018 12:09 am
- Forum: Limiting Reactant Calculations
- Topic: Reactant vs. Reagent [ENDORSED]
- Replies: 23
- Views: 34861
Re: Reactant vs. Reagent [ENDORSED]
A reagent is used in a reaction and a reactant undergoes a change in a reaction.