## Search found 33 matches

Sat Mar 16, 2019 11:31 am
Forum: Administrative Questions and Class Announcements
Topic: LYNDON'S PORK RAMEN REVIEW
Replies: 37
Views: 3529

### Re: LYNDON'S PORK RAMEN REVIEW

For number 9 part d do we have all the information we need to solve the problem? I'm assuming we will have to solve for the standard cell potential and find the difference between that and this new cell potential, I just don't know how to get there.
Thu Mar 14, 2019 4:41 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Review Session-Thermo-files- Wednesday-Q11-clarification [ENDORSED]
Replies: 10
Views: 837

### Re: Review Session-Thermo-files- Wednesday-Q11-clarification[ENDORSED]

Number 8 asks for the enthalpy change per mol so wouldn't you have to convert 2000g to moles of BaSo4 and then solve per mol?
Tue Mar 12, 2019 11:22 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Step
Replies: 6
Views: 170

### Re: Slow Step

Given a rate law we could identify the slow step out of a list of steps because we know that it is the rate determining step so the law will be based ooff of its reactants.
Tue Mar 12, 2019 11:18 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Determining the rate constant when given trials
Replies: 3
Views: 199

### Re: Determining the rate constant when given trials

For this particular question, you are using ones where concentrations aren't all constant because on of the reactants is zero order and does not effect the rate law. As far as dividing things goes, that is just to show the ratio of the concentration in one reaction to that of another and then compar...
Tue Mar 12, 2019 11:11 am
Forum: First Order Reactions
Topic: first order intergrated rate laws
Replies: 2
Views: 138

### Re: first order intergrated rate laws

Most of the time when you are working with integrated rate laws it will be because a reaction happened over a specific amount of time with an initial and final concentration. You will be asked to solve for one of the variables given the others and will use the integrated rate law to solve for this c...
Tue Mar 05, 2019 11:07 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Galvanic Cells
Replies: 4
Views: 211

### Re: Galvanic Cells

Think of it like a battery being used up. After all of the reactants have gone to products, there is no more ability for it to create energy from the reaction.
Tue Mar 05, 2019 11:05 am
Forum: General Rate Laws
Topic: Order of Reaction
Replies: 6
Views: 254

### Re: Order of Reaction

Find the individual orders of each reaction based on how the rate changes with additional initial concentration of the reactants. Each reactant will have its own individual order and then you will take the sum of the orders of the reactants to find the overall order of the reaction.
Tue Mar 05, 2019 11:02 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Unique/Formation and Degradation
Replies: 2
Views: 123

### Re: Unique/Formation and Degradation

When thinking about the unique vs individual rate, I look at what Dr. Lavelle went over in class with one over the coefficient times the rate of change. Each species will have the same unique rate (one over coefficient times individual rate) but different individual rates if they have different coef...
Thu Feb 28, 2019 7:08 am
Forum: Balancing Redox Reactions
Topic: Acidic Solutions
Replies: 7
Views: 321

### Re: Acidic Solutions

Also, don't forget that adding hydronium ions adds electrons to that side when you are balancing the electrons later.
Thu Feb 28, 2019 6:52 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Order of Aqueous
Replies: 2
Views: 118

### Re: Order of Aqueous

It depends whether it is the cathode or the anode. You write the reactant first and then the product, so you would have to determine if it is the oxidation or reduction half reaction to determine the order.
Thu Feb 28, 2019 6:49 am
Forum: Balancing Redox Reactions
Topic: Basic Solutions
Replies: 3
Views: 165

### Re: Basic Solutions

I always start with balancing with H20 and then move on to OH- or H+. Makes it easier for me. The one that you use depends on the type of solution you are in, and balance other parts of the reaction before you start adding hydrogens and oxygens.
Fri Feb 22, 2019 11:41 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free energy
Replies: 5
Views: 238

### Re: Gibbs Free energy

Sometimes, if given enough values, you may have the use the equation PV=nRT to solve for temperature.
Fri Feb 22, 2019 11:38 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G=0 at equilibrium
Replies: 4
Views: 431

### Re: Delta G=0 at equilibrium

Gibbs free energy is the energy free to do work. At equilibrium, no net energy is being gained or lost (nothing is really changing). Thus, at equilibrium, Delta G is 0.
Fri Feb 22, 2019 11:34 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Favor ability of Cell portential
Replies: 5
Views: 286

### Re: Favor ability of Cell portential

A positive cell potential means spontaneous, a negative cell potential means not spontaneous. Think of the equation Delta G = -nFE. Negative delta G is spontaneous, and n (electrons transferred) and F (Faraday's constant) are always positive. Thus the, the sign of E (cell potential) determines wheth...
Tue Feb 12, 2019 11:22 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Change by Volume and Pressure
Replies: 2
Views: 115

### Re: Entropy Change by Volume and Pressure

No. You just pick one of the values and use it to solve for the change in entropy.
Tue Feb 12, 2019 11:19 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isochoric vs isometric
Replies: 4
Views: 663

### Re: Isochoric vs isometric

Isochoric is constant volume, Isobaric is constant pressure, Isothermal is constant temperature. I don't think we have done any work with Isometric.
Tue Feb 12, 2019 11:14 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Liquids in K expression
Replies: 2
Views: 163

### Re: Solids and Liquids in K expression

Balance your equation first and then omit the ones that are solids are liquids.
Sun Feb 10, 2019 11:22 pm
Forum: Administrative Questions and Class Announcements
Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
Replies: 49
Views: 3852

### Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!

You can solve for temp using PV=nRT. I keep getting a wack answer for this question, however. I'm assuming the overall delta U and delta S will be zero because they are state functions, but I am not getting the right q and w quantities. Can someone who feels confident put down their values so I can ...
Wed Feb 06, 2019 10:15 am
Forum: Phase Changes & Related Calculations
Topic: Heating Curve
Replies: 4
Views: 179

### Re: Heating Curve

Think of the heat capacity as the amount of heat something can absorb. The larger the value, the more heat it will be able to absorb before it transitions to the next phase. If it can absorb more heat,it will take longer for this process to happen and will thus have a less steep slope.
Wed Feb 06, 2019 10:12 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Constant Pressure Calorimeter
Replies: 5
Views: 465

### Re: Constant Pressure Calorimeter

Most calorimeters we work with should be isolated or closed systems. I don't think any of them will be open.
Wed Feb 06, 2019 10:07 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm [ENDORSED]
Replies: 49
Views: 2042

### Re: Midterm[ENDORSED]

Homework problems as well as watching youtube videos on certain concepts has worked well for me. Professor Dave Explains on youtube has some good videos that explains concepts pretty clearly.
Tue Jan 29, 2019 9:58 pm
Forum: Phase Changes & Related Calculations
Topic: Internal Energy
Replies: 1
Views: 110

### Re: Internal Energy

I believe the kinetic portion has to do with the movement in all direction of a molecule of a substance and the potential portion has to do with the energy that held inside the bonds of that substance.
Tue Jan 29, 2019 9:47 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: HW Q
Replies: 2
Views: 122

### Re: HW Q

Basically, a change in, say, 10 degrees celsius is the same as a change in 10 Kelvin. So when you're using a value for change in temperature in the equation you can use celsius and Kelvin interchangeably.
Tue Jan 29, 2019 9:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Std enthalpy combustion
Replies: 1
Views: 47

### Re: Std enthalpy combustion

If we need to use that combustion reaction to solve for the enthalpy of a different net reaction, that value will be given to us. If we are asked to actually find the enthalpy of the combustion reaction we can use any of the methods to solve for enthalpy we learned in lecture. Either way, some value...
Thu Jan 24, 2019 4:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Tricks for identifying Strong/Weak Acids & Bases
Replies: 5
Views: 232

### Re: Tricks for identifying Strong/Weak Acids & Bases

Anytime we are given a Ka or Kb, the acid or base is almost certainly going to be weak. This is because the Ka or Kb of a strong acid or base is extremely high because the substance gets basically completely deprotonated/protonated. This should help you in identifying weak substances right away, and...
Thu Jan 24, 2019 4:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% Rule and % Deprotonation
Replies: 3
Views: 166

### Re: 5% Rule and % Deprotonation

Just for future reference and ease on test problems, any time the constant value is lower than 1 x 10^-3 it should be safe to use an approximation. You can use the % deprotonation rule to check afterwards if you are worried, but this will save you some time on exams.
Thu Jan 24, 2019 4:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Autoprotolysis
Replies: 3
Views: 191

### Re: Autoprotolysis

I believe it is any value higher than 1 x 10^-7 that will make a difference in the PH.
Tue Jan 15, 2019 11:05 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th edition Question 11.45
Replies: 2
Views: 77

### Re: 6th edition Question 11.45

Because the equilibrium constant of the decomposition of Cl2 is less than that of the decomposition reaction for F2, there are less products in the chlorine reaction than the fluorine reaction. This shows that the chlorine is more likely to keep its original form and not decompose as much, showing i...
Tue Jan 15, 2019 11:00 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question on 12.41
Replies: 3
Views: 124

### Re: Question on 12.41

Also, in regards to the strengths of acids and bases based on their equilibrium constants, a lower Kx (Ka or Kb) shows a weaker substance. A lower Kx also responds to a higher PKx if those are the values you are looking at, so a higher PKx would be weaker.
Tue Jan 15, 2019 10:56 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Predict Solubility
Replies: 1
Views: 81

### Re: Predict Solubility

The higher the equilibrium constant is, the more the reaction favors the products and thus the more the compound is dissociated if it is reacting with water. This would represent a higher solubility.
Thu Jan 10, 2019 12:27 pm
Forum: Ideal Gases
Topic: Reaction Quotient
Replies: 5
Views: 227

### Re: Reaction Quotient

When you have a reaction that consists of only gasses, you use their partial pressures in the equation that we learned to find the Kp value. When the reaction consists of compounds in a non gas state (for instance aqueous) you would plug in the concentrations of the products and reactants into the s...
Thu Jan 10, 2019 12:23 pm
Forum: Ideal Gases
Topic: Identifying gases in equilibrium via pictures
Replies: 2
Views: 120

### Re: Identifying gases in equilibrium via pictures

This is because there is no change in the composition of the solution from flask 3 to 4. To simplify things, look at the number of ions stuck together and those floating around freely. As the pictures progress, more ions are floating around freely, but in flask 3 and 4 there are the same number of d...
Thu Jan 10, 2019 12:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Concentrations
Replies: 4
Views: 131

### Re: Equilibrium Concentrations

K is the value of the concentrations of the products over the reactants at equilibrium, thus we would only ever use equilibrium concentrations to find K. Any other concentrations we are given at a particular point in the reaction should be put into the same equation we have been practicing in class....

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