Search found 52 matches
- Wed Mar 11, 2020 2:15 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 7D1
- Replies: 4
- Views: 100
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: 380
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: 547
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: 64
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: 91
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: 56
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: 47
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: 125
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: 51
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: 185
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: 71
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: 75
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: 209
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: 88
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: 146
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: 96
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: 46
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: 172
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: 101
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: 28
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: 34
electromotive force
What is electromotive force?
- Sun Mar 01, 2020 11:57 pm
- Forum: General Rate Laws
- Topic: determining rate
- Replies: 2
- Views: 61
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: 29
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: 114
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: 75
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: 106
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: 5
- Views: 943
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: 106
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: 99
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: 110
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: 63
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: 83
% 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: 77
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: 97
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: 38
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: 67
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: 24
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: 54
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: 39
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: 192
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: 56
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: 154
∆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: 96
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: 78
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: 42
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: 29
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: 18
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: 40
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: 78
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: 94
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: 244
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: 40
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?