## Search found 52 matches

Wed Mar 11, 2020 2:15 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 7D1
Replies: 4
Views: 70

### Re: 7D1

What equation are they using in this problem? Honestly I thought that the solution guide answer was confusing. To solve, use the equation ln(kr2/kr1) = Ea/R(1/T1 - 1/T2), found on page 623 of the textbook. You use .87 for kr2, .76 for kr1, 8.31•10^-3 for R, 1000 for T1, and 1030 for T2, and solve f...
Wed Mar 11, 2020 12:15 am
Forum: Administrative Questions and Class Announcements
Topic: What is the plan for the final?
Replies: 16
Views: 255

### Re: What is the plan for the final?

The email was sent! He said it will be a short, straightforward, open book, take home final. All other review sessions and lecture are cancelled.
Mon Mar 09, 2020 12:11 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: units of T
Replies: 11
Views: 431

### Re: units of T

It is almost always seconds, but the problem typically specifies. It's usually best to write units with each step though, so that way it can easily be converted to another unit if necessary.
Mon Mar 09, 2020 12:10 am
Forum: General Rate Laws
Topic: Integrated Rate Laws
Replies: 3
Views: 38

### Re: Integrated Rate Laws

If I'm not mistaken, it gives us the instantaneous rate of an equation via the slope
Mon Mar 09, 2020 12:08 am
Forum: Balancing Redox Reactions
Topic: balancing reactions
Replies: 6
Views: 38

### balancing reactions

I'm super confused on the steps to balancing redox reactions. Can someone explain it to me in simpler terms than the textbook, or does anyone know of a good resource explaining how it is done?
Mon Mar 09, 2020 12:05 am
Forum: Administrative Questions and Class Announcements
Topic: How do we access Sapling Learning
Replies: 2
Views: 44

### Re: How do we access Sapling Learning

I did not take 14A with Lavelle, so I only bought access for 1 quarter for now. Yes, I had to pay \$64. According to the instruction sheet online, it said to use "use credit" to avoid paying, but I'm assuming that that meant if you had purchased access from a previous quarter...I couldn't f...
Mon Mar 09, 2020 12:01 am
Forum: General Rate Laws
Topic: Integrated Rate Law
Replies: 3
Views: 35

### Re: Integrated Rate Law

Yes, because it is determined by looking at the slope at a given point, which is instantaneous.
Mon Mar 09, 2020 12:00 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n=2
Replies: 7
Views: 77

### Re: n=2

If you are talking about the G=-nFe equation, n is the number of electrons transferred...I was also confused on the examples in the book though
Sun Mar 08, 2020 11:59 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Theory
Replies: 3
Views: 32

### Re: Arrhenius Theory

Arrhenius theory states that acids dissociate in water to yield electrically charged atoms or molecules (ions), H+, and that bases ionize in water to yield hydroxide ions (OH−).
Sun Mar 08, 2020 11:57 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: E cell
Replies: 9
Views: 117

### Re: E cell

I believe that E standard cell is the standard state cell potential, and then Ecell is the cell potential at non standard state conditions.
Sun Mar 08, 2020 11:55 pm
Forum: General Rate Laws
Topic: Making one reactant concentration small
Replies: 3
Views: 39

### Re: Making one reactant concentration small

I think that this is done to isolate one of the reactants in order to see the change
Sun Mar 08, 2020 11:54 pm
Forum: General Rate Laws
Topic: Elementary reactions
Replies: 5
Views: 33

### Re: Elementary reactions

I think that it just means simple reactions without a lot of complex molecules and numbers involved, basically nothing beyond the equation examples in the homework problems.
Sun Mar 08, 2020 11:46 pm
Forum: Balancing Redox Reactions
Topic: Balancing redox with h2o
Replies: 9
Views: 121

### Re: Balancing redox with h2o

I was also wondering how this would be done, I've seen it done with H2O, H+, and OH- and other elements, but I don't know how it would be done with just these three...
Sun Mar 08, 2020 11:38 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: K’
Replies: 4
Views: 43

### Re: K’

I think that K' is the reverse rate constant of the reaction
Sun Mar 08, 2020 11:36 pm
Forum: Administrative Questions and Class Announcements
Topic: Formula Sheet
Replies: 7
Views: 76

### Re: Formula Sheet

I assumed it is the same one that we've had on the last test, isn't that the same one on the website?
Sun Mar 08, 2020 11:35 pm
Forum: General Rate Laws
Topic: First vs Second vs Zero Order
Replies: 7
Views: 53

### Re: First vs Second vs Zero Order

It is determined by the rate, so a zero order reaction is one at a constant rate. A first order reaction is dependent on the concentration of only one of the reactants. A second order reaction is proportional to either the product of two concentrations, or a single reactant's concentration squared.
Sun Mar 08, 2020 11:32 pm
Forum: General Rate Laws
Topic: Pseudo rate law
Replies: 3
Views: 28

### Re: Pseudo rate law

I'm not entirely sure but I think it is when you are trying to determine the rate for one specific reactant, so you isolate it, and make the other reactants constant.
Sun Mar 08, 2020 11:30 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: G=-nFe
Replies: 7
Views: 105

### G=-nFe

I know that in the G=-nFe equation, n is the number of electrons transferred. Does that mean the electrons transferred from 1 compound to another? I'm confused because in a lot of equations, everything rearranges from one side to the other...
Wed Mar 04, 2020 6:28 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: concentration cells
Replies: 4
Views: 61

### concentration cells

How do concentration cells differ from galvanic cells? What is an example of one?
Wed Mar 04, 2020 6:26 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Metal Dissolving in Solutions
Replies: 1
Views: 26

### Metal Dissolving in Solutions

How can you predict if a metal will dissolve in a solution?
Sun Mar 01, 2020 11:59 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: electromotive force
Replies: 1
Views: 23

### electromotive force

What is electromotive force?
Sun Mar 01, 2020 11:57 pm
Forum: General Rate Laws
Topic: determining rate
Replies: 2
Views: 38

### determining rate

I'm having difficulty with determining rates of equations when a list of concentrations is given. How is the rate determined?
Sun Mar 01, 2020 11:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: anodes and cathodes
Replies: 1
Views: 14

### anodes and cathodes

How can you tell which side is the anode and which side is the cathode?
Sun Mar 01, 2020 11:47 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: free energy and work
Replies: 5
Views: 69

### free energy and work

What is the relationship between free energy and work?
Sun Mar 01, 2020 11:37 pm
Forum: Zero Order Reactions
Topic: order of reactions
Replies: 4
Views: 46

### order of reactions

How can you determine if a reaction is zero, first, or second order?
Sun Feb 23, 2020 11:13 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 3
Views: 69

### Van't Hoff Equation

The Van't Hoff Equation shows temperature dependence of K, but I'm still a little confused on what that means, and does the equation in any way connect to ∆H, ∆S, and ∆G?
Sun Feb 23, 2020 10:53 pm
Forum: Environment, Fossil Fuels, Alternative Fuels
Topic: Why ethanol?
Replies: 4
Views: 886

### Re: Why ethanol?

It is said to be somewhat of a stepping stone, because it is less harmful than petroleum, coal, or natural gas in many ways, but still worse than solar or wind or other renewables. However, I do strongly feel that there is a lot more that the world can do in terms of investing straight into other re...
Sun Feb 23, 2020 10:44 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: spontaneous reactions
Replies: 2
Views: 58

### spontaneous reactions

What exactly does a reaction being spontaneous mean in terms of thermodynamics, and what occurs when ∆S and ∆H are either both negative or both positive?
Sun Feb 23, 2020 10:42 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: applying gibbs free energy
Replies: 5
Views: 66

### applying gibbs free energy

What exactly does Gibbs free energy tell us about an equation? How is it applied?
Sun Feb 23, 2020 10:27 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Boltzmann Equation
Replies: 2
Views: 75

### Boltzmann Equation

I'm a little confused as to what exactly the Boltzmann equation is trying to explain in terms of entropy. When is it usually applied?
Wed Feb 12, 2020 2:35 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong Acids
Replies: 2
Views: 41

### Strong Acids

How can a strong acid be identified from looking at a chemical equation? Is there a way to tell, or do they have to just be memorized?
Mon Feb 10, 2020 12:00 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: % dissociation
Replies: 5
Views: 45

### % dissociation

Can someone please explain what % dissociation means and how it is calculated?
Sun Feb 02, 2020 11:59 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: work and volume
Replies: 4
Views: 56

### Re: work and volume

When volume decreases, the work of a system is positive as the surroundings have performed work on the system, creating energy. When volume increases, the opposite is true, as the system performed work, losing it, making it negative, as it has lost energy.
Sun Feb 02, 2020 11:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: state functions
Replies: 10
Views: 81

### Re: state functions

A good example of state vs path functions is thinking of two points on a map, A and B, that are 100 km apart if you were to draw a straight line from one to the other. That 100km is representative of a state function. There are two roads to get from A to B, one road is 120km, the other is 180km. Thi...
Sun Feb 02, 2020 11:55 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Intensive vs Extensive properties
Replies: 2
Views: 29

### Intensive vs Extensive properties

What is the difference between intensive and extensive properties, and what are some examples of each?
Sun Feb 02, 2020 11:52 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Universe Closed System
Replies: 3
Views: 44

### Re: Universe Closed System

The universe (supposedly) is not exchanging any energy or matter with something outside of the universe, therefore being isolated. Yes energy and matter exchanges happen within, but within the universe as a whole, no energy would be lost to something outside.
Sun Feb 02, 2020 11:43 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Gases vs liquids and solids
Replies: 1
Views: 19

### Re: Gases vs liquids and solids

Liquids and solids behave differently than gas. With solids, the volume is fixed so the typical way of calculating enthalpy would not work, and both solids and liquids behave differently than gasses when compressed. However, enthalpy of phase changes can be calculated.
Sun Feb 02, 2020 11:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy
Replies: 7
Views: 49

### Re: enthalpy

Enthalpy is the total heat quantity of a system, the internal energy (U) plus the product of pressure and volume (PV)
Sun Feb 02, 2020 11:35 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Open/Closed/Isolated System
Replies: 3
Views: 30

### Re: Open/Closed/Isolated System

If you mean by having mass be exchanged and energy conserved, I do not believe so. Isolated systems are the only systems in which energy is not exchanged with its surroundings, and those are difficult to come by as isolating anything from energy exchange is nearly impossible. I'm not sure that you w...
Sun Feb 02, 2020 11:33 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Types of Systems
Replies: 7
Views: 116

### Re: Types of Systems

Open system: exchanges energy and matter with surroundings Closed system: exchanges energy, but not matter, with surroundings Isolated system: exchanges neither energy nor matter with surroundings An example to help remember this is by thinking of cooking a liquid in a pot on a stove. If the lid is ...
Sun Jan 26, 2020 11:26 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy/state properties
Replies: 4
Views: 47

### enthalpy/state properties

Can someone please explain what makes enthalpy a state property?
Sun Jan 26, 2020 11:24 pm
Forum: Phase Changes & Related Calculations
Topic: ∆H
Replies: 17
Views: 131

### ∆H

Is looking at ∆H the only way to determine whether a reaction is exothermic or endothermic?
Sun Jan 26, 2020 11:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: autoprotolysis
Replies: 7
Views: 78

### autoprotolysis

I understand that autoprotolysis is the transfer of an H+ from an acid to a base in an equation (I think), I'm unclear on how pKW = pH + pOH is derived from it though.
Sun Jan 26, 2020 11:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: calculating % ionization
Replies: 4
Views: 64

### calculating % ionization

I'm a little confused on how you calculate the percent ionization of an acid or a base, and what that means.
Sun Jan 26, 2020 11:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKa/pKb
Replies: 3
Views: 38

### pKa/pKb

I don't fully understand how pKa and pKb are related to pH and Ka/Kb. Can someone please explain what pKa and pKb are?
Sun Jan 19, 2020 11:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pressure
Replies: 1
Views: 27

### Re: Pressure

This occurs with gases. When pressure is applied to gas equations, the rate of reaction speeds up, therefore causing it to shift to the side with fewer molecules of gas.
Sun Jan 19, 2020 11:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Reaction mixture at equilibrium
Replies: 2
Views: 15

### Re: Reaction mixture at equilibrium

If you mean composition, as in concentration, it is because the forward reaction and reverse reaction are occurring at the same rate, so there is no net change in concentration/state/etc.
Sun Jan 19, 2020 11:16 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: reaction quotient
Replies: 4
Views: 38

### Re: reaction quotient

Q, the reaction quotient, measures the amounts of reactants and products during a reaction at a specific point in time, and can be calculated before the reaction reaches equilibrium. So if the reaction has not reached equilibrium yet, the product/reactant ratio is Q, and is giving information that c...
Sun Jan 19, 2020 11:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: identifying acids & bases
Replies: 5
Views: 50

### identifying acids & bases

I took 14A a while ago and honestly don't have a strong foundation on acids and bases. How, when looking at an equation, do you identify the acid, base, conjugate acid, and conjugate base just by looking at it? Is that something that needs to be memorized?
Sun Jan 12, 2020 5:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp and Kc
Replies: 4
Views: 68

### Re: Kp and Kc

aq and g are state symbols. If a reaction has multiple sate symbols, it is heterogeneous, so yes, it can occur. If the state symbols are the same, it is a homogeneous reaction. Kp and Kc are just measures of concentration or pressure, so it depends what you are looking for in the reaction.
Sun Jan 12, 2020 5:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units for K
Replies: 21
Views: 207

### Re: Units for K

K is representative of a ratio, products/reactants. It is used to compare rates of reaction and therefore does not have units.
Sun Jan 12, 2020 5:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between Kc/Kp and Q
Replies: 2
Views: 32

### Difference between Kc/Kp and Q

I was confused about the difference between Kc or Kp and Q. They are both [products]/[reactants], so how are they different?