## Search found 30 matches

Sun Mar 17, 2019 12:48 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: K vs k1/k'1
Replies: 6
Views: 487

### Re: K vs k1/k'1

I do not think it really matters which one you write it as. It is however important to know that K is equal to k1/k'1 if you are only given the values of k1 and k'1 and not a value for K.
Thu Mar 14, 2019 9:50 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Hydronium
Replies: 2
Views: 118

### Re: Hydronium

If there are hydronium ions in your balanced redox reaction, they should be included in your cell diagram.
Mon Mar 11, 2019 12:43 am
Forum: Zero Order Reactions
Topic: Integration/Derivation
Replies: 3
Views: 285

### Re: Integration/Derivation

I do not believe that derivation/integration would be asked of us, simply how to apply the derived formulas to problems.
Mon Mar 11, 2019 12:41 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous Reaction
Replies: 5
Views: 406

### Re: Spontaneous Reaction

I am also confused. I understand that delta H would be negative if you are freezing and thus losing heat, but wouldn't delta S also be negative if you are losing entropy going from a liquid to a solid? Thanks in advance!
Mon Mar 11, 2019 12:07 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Potential
Replies: 2
Views: 104

### Re: Cell Potential

You would want to use a cathode with the weakest reducing power (strongest oxidizing power) and an anode with the weakest oxidizing power (strongest reducing power).
Mon Mar 11, 2019 12:04 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 3
Views: 152

### Re: Cell Diagram

H+ is included in the cell diagram, but H2O (l) and electrons are not.
Sun Mar 10, 2019 11:17 pm
Forum: First Order Reactions
Topic: Half-Life
Replies: 7
Views: 243

### Re: Half-Life

Typically we would use the half-life formula to determine how long an element has been decaying.
Sun Mar 10, 2019 11:08 pm
Forum: General Rate Laws
Topic: Rate Laws
Replies: 8
Views: 261

### Re: Rate Laws

I think he shows us the derivation to establish some kind of fundamentals, but it really just confuses the [censored] out of me. I don't think we would ever be asked to derive them on a test, just to apply them to problems similar to homework and tests.
Sat Mar 09, 2019 4:50 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M. 1 7th Edition
Replies: 2
Views: 99

### Re: 6M. 1 7th Edition

This sounds like the question is just trying to be tricky. We were taught to write anode on the left and cathode on the right.
Sat Mar 09, 2019 4:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating E naught
Replies: 5
Views: 249

### Re: Calculating E naught

Given the reduction half reactions, you will use the appendix to find E naught values. The lower E naught value is the anode because it is the stronger reducing agent. Then, to get E naught of the cell you do cathode - anode = E naught cell
Sat Mar 09, 2019 4:05 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: negative and k
Replies: 3
Views: 155

### Re: negative and k

K cannot be negative because you can't have a negative concentration
Wed Feb 27, 2019 8:30 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cell Diagram [ENDORSED]
Replies: 3
Views: 216

### Re: Galvanic Cell Diagram[ENDORSED]

Molecules of the same phase in the cell diagram are written in the order: oxidized, reduced
Sun Feb 24, 2019 1:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Oxidation and Reduction
Replies: 3
Views: 120

### Re: Oxidation and Reduction

I think the most important thing is that the electrons are on opposite sides in reduction vs oxidation half reactions, but given that that is how we did it in class I assume that is how we should do it on an exam.
Sun Feb 24, 2019 1:38 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n value
Replies: 11
Views: 256

### Re: n value

n is moles so I assume it will either be a given value or we will need to convert to moles from a given mass of a compound or element.
Sun Feb 24, 2019 1:37 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Spontaneous cell reaction
Replies: 2
Views: 102

### Re: Spontaneous cell reaction

Because the equation is delta G = -nFE, a positive cell potential (or E value) results in a negative delta G, and thus a spontaneous reaction.
Mon Feb 18, 2019 5:53 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 4
Views: 161

### Re: Gibbs Free Energy

K is the equilibrium constant. Concentration of products at equilibrium over the concentration of reactants at equilibrium.
Mon Feb 18, 2019 5:52 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 4
Views: 163

### Re: Van't Hoff Equation

I'm pretty sure R is the ideal gas constant
Mon Feb 18, 2019 5:43 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy
Replies: 3
Views: 118

### Re: Entropy

Entropy is a state function and thus increases or decreases in a phase change. As said above, solids have the lowest entropy, then liquid, and gases have the highest entropy.
Sun Feb 03, 2019 10:39 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Open vs Closed System
Replies: 13
Views: 1057

### Re: Open vs Closed System

In a closed system, only energy can exchange with surroundings. An example is a sealed beaker of water. You cannot change the volume but you can heat the container because it isn't insulated and thus change the energy.
Sun Feb 03, 2019 10:27 pm
Forum: Calculating Work of Expansion
Topic: Work sign changes
Replies: 3
Views: 163

### Re: Work sign changes

I believe this is because the formula is w = - P (delta V). If it is expansion, delta V will be positive and thus work negative. In compression delta V is negative and thus work is positive.
Sun Feb 03, 2019 10:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Quiz 1 Number 3c
Replies: 6
Views: 237

### Re: Quiz 1 Number 3c

The units should be mol/L (Molarity) because it's asking for the concentration.
Sun Jan 27, 2019 5:21 pm
Forum: Ideal Gases
Topic: Calculating partial pressure
Replies: 4
Views: 185

### Re: Calculating partial pressure

You may be able to if you are given a concentration: n/V, or moles/liter.
Sun Jan 27, 2019 3:36 pm
Forum: Ideal Gases
Topic: Approximations for ICE
Replies: 20
Views: 531

### Re: Approximations for ICE

You can use approximations if the Ka value is less than 1x10^-3. You should check to see that it was appropriate to use approximation by seeing if the equilibrium concentration is less than 5% of the initial concentration.
Sun Jan 27, 2019 3:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKa values
Replies: 3
Views: 156

### Re: pKa values

I'm not sure if there is an index of these values. They should be given to you by problem or the problem may tell you to look at a table to find the pKa or Ka values. Also if you are given the Ka you know the pKa and vice versa.
Sun Jan 20, 2019 4:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Bars vs. Molarity
Replies: 5
Views: 209

### Re: Bars vs. Molarity

bars are a unit of pressure just like atm or TORR
Sun Jan 20, 2019 4:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Autoprotolysis
Replies: 3
Views: 94

### Re: Autoprotolysis

The equation is 2H2O → H3O + + OH-. The significance is that shows that water is amphoteric (able to react as an acid and a base).
Sun Jan 20, 2019 3:33 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: HW Q
Replies: 2
Views: 72

### Re: HW Q

You have to dilute the solution by multiplying .025M(200ml/250ml). Then, take the negative log of that new concentration and you should get the correct pH.
Sun Jan 13, 2019 3:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equations
Replies: 6
Views: 227

### Re: Equations

Kp = Kc x (RT) ^ stoichiometric coefficient

In general, Kp uses partial pressures and Kc uses concentrations
Sun Jan 13, 2019 2:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between Kc, Kp, and K
Replies: 2
Views: 123

### Re: Difference between Kc, Kp, and K

Kc: concentration of products over concentration of reactants when at equilibrium
Kp: partial pressures of products over partial pressures of reactants when at equilibrium
Sun Jan 13, 2019 2:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE table question
Replies: 2
Views: 85

### Re: ICE table question

So far we have typically used ICE tables to calculate equilibrium concentrations of the products and reactants when given a Kc and initial concentrations.