## Search found 31 matches

Sat Mar 17, 2018 8:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Roomie Love <3
Replies: 1
Views: 328

### 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: 426

### 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: 440

### 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: 429

### 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: 223

### 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: 125

### 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
Replies: 2
Views: 223

### 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: 471

### 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: 324

### 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: 401

### 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: 185

### 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: 20525

### 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: 222

### 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: 507

### 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: 309

### 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: 207

### 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: 176

### 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: 175

### 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: 276

### 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: 402

### 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: 291

### 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: 170

### 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: 209

### 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: 165

### 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: 153

### 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: 151

### 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: 190

### 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: 81

### 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: 608

### 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: 1666

### 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: 18527

### Re: Reactant vs. Reagent[ENDORSED]

A reagent is used in a reaction and a reactant undergoes a change in a reaction.