Search found 31 matches

by Alejandra Rios 1L
Tue Mar 13, 2018 9:48 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.61
Replies: 4
Views: 139

Re: 15.61

For that question I was also wondering if we would be given the formula on the final formula sheet? I don't think I saw it on the formula sheet posted on the 14B website I noticed that the equation wasn't on the formula sheet as well, so I think we will have to remember this equation or know how to...
by Alejandra Rios 1L
Tue Mar 13, 2018 9:42 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediate
Replies: 6
Views: 139

Re: Intermediate

Intermediates can be identified when one of the products of a reaction is a reactant in a further step, meaning that the molecule was consumed. Also, the intermediates will not appear in the overall reaction.
by Alejandra Rios 1L
Tue Mar 13, 2018 9:37 am
Forum: *Enzyme Kinetics
Topic: Catalysts
Replies: 11
Views: 298

Re: Catalysts

Yes, a catalyst works to lower activation energy, therefore this corresponds to the rate of both the forward and reverse reactions.
by Alejandra Rios 1L
Thu Mar 08, 2018 5:53 pm
Forum: First Order Reactions
Topic: 15.23C
Replies: 6
Views: 262

Re: 15.23C

The coefficients in the equation don't have an effect on the order. If the problem says its first-order then the reaction should be able to be worked out using the equations we have for first-order reactions.
by Alejandra Rios 1L
Thu Mar 08, 2018 5:49 pm
Forum: Second Order Reactions
Topic: 15.35a
Replies: 3
Views: 219

Re: 15.35a

This should be a rounding error, if you were to use 0.024 as the k value you would get 744.05 as your final answer which is equivalent to 7.4 x 10^2, however if you were to leave the whole decimal, this would give you a value of 757.62. I think both answers would be correct as long as you provided t...
by Alejandra Rios 1L
Thu Mar 08, 2018 5:39 pm
Forum: Second Order Reactions
Topic: 15.35
Replies: 3
Views: 198

Re: 15.35

This is based upon the fact that the question is asking for the half-life of second order reactions, the previous problems which only involved k are for first order reactions. Second order reactions also include the initial concentration of the reactants.
by Alejandra Rios 1L
Sat Mar 03, 2018 2:18 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Reaction
Replies: 6
Views: 135

Re: Arrhenius Reaction

We have not covered it in class yet, but there is no need to know it for test 3! Test 3 will only cover 15.1-15.6
by Alejandra Rios 1L
Sat Mar 03, 2018 2:14 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: When do we calculate for k
Replies: 3
Views: 103

Re: When do we calculate for k

If there is a table given, you could use that to find the k value; however, there are cases where the problem will ask you to solve for k and you will have to use the equations we have derived for each reaction and solve for k with the given information. If a problem were to come up and it doesn't d...
by Alejandra Rios 1L
Sat Mar 03, 2018 2:08 pm
Forum: General Rate Laws
Topic: Test 3
Replies: 5
Views: 124

Re: Test 3

My TA also said it was necessary to know how to derive all the equations for test 3.
by Alejandra Rios 1L
Wed Feb 21, 2018 12:17 am
Forum: Balancing Redox Reactions
Topic: Balancing REDOX reactions
Replies: 5
Views: 167

Re: Balancing REDOX reactions

The value of E should be the same after this is undergone.. there is no need to multiply by the factor.
by Alejandra Rios 1L
Wed Feb 21, 2018 12:15 am
Forum: Balancing Redox Reactions
Topic: Writing Half-Reactions
Replies: 6
Views: 181

Re: Writing Half-Reactions

If you are not able to identify the anode and cathode then you should flip one since you need a redox reduction (containing a reduced and oxidized form)
by Alejandra Rios 1L
Tue Feb 20, 2018 1:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: anode?
Replies: 5
Views: 169

Re: anode?

An anode occurs when oxidation takes place, for this specific example it would be zinc.
by Alejandra Rios 1L
Tue Feb 20, 2018 1:40 pm
Forum: Balancing Redox Reactions
Topic: "Rules"
Replies: 7
Views: 181

Re: "Rules"

14.1 and 14.2 in the book displays two different sets of rules that you can follow!
by Alejandra Rios 1L
Wed Feb 14, 2018 3:30 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 2
Views: 247

Re: Van't Hoff Equation

It is part of the chapters that we covered in class so there is a possibility of it being on the exam. We also had a couple questions in the review sessions which included Van't Hoff so I would be familiar with the material and problem solving.
by Alejandra Rios 1L
Wed Feb 14, 2018 3:26 pm
Forum: Van't Hoff Equation
Topic: Derivation
Replies: 9
Views: 321

Re: Derivation

You don't necessarily have to know the steps on how to derive the equation, but it would be helpful to know where the equation comes from so that you can be able to interchange between equations if you needed to, and also so that you can understand the equation and know when it can be applied.
by Alejandra Rios 1L
Thu Feb 08, 2018 9:22 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 11.17
Replies: 10
Views: 270

Re: 11.17

Your answer is correct, there are some typos in the solutions manual which can be found on Dr. Lavelle's website under course materials and titled solution manual errors. Here, Lavelle states, "11.17 Typo. The answer is -2.7 kJ.mol-1. (not -27 kJ.mol-1.,"
by Alejandra Rios 1L
Thu Feb 08, 2018 9:17 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 9
Views: 205

Re: Spontaneity

A -ΔG indicates that the reaction is spontaneous and exothermic, while a +ΔG indicates that the reaction is non spontaneous and endothermic. However, when dealing with a +ΔG we can say that the reverse reaction is favored since it is spontaneous in the reverse direction
by Alejandra Rios 1L
Thu Feb 08, 2018 9:15 pm
Forum: Balancing Redox Reactions
Topic: Basic vs. Acidic
Replies: 6
Views: 134

Re: Basic vs. Acidic

When dealing with acids and bases, the balancing of equations would be effected. This is based on the H+ present in acid and OH- present in bases which needs to be accounted for in the reaction.
by Alejandra Rios 1L
Sun Feb 04, 2018 7:23 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: syllabus
Replies: 4
Views: 150

Re: syllabus

This next chapter should be included in the syllabus and in the midterm, but it also depends on how much is covered in class before the exam.
by Alejandra Rios 1L
Wed Jan 31, 2018 1:54 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: A spontaneous reaction
Replies: 7
Views: 153

Re: A spontaneous reaction

A spontaneous reaction is a reaction which is driven by the energy which is already present in the system. This means that it is the more natural reaction that can occur with the given amount of energy from the reactants. Spontaneous reactions have a -ΔG value since they give off energy. I believe t...
by Alejandra Rios 1L
Wed Jan 31, 2018 1:33 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy: State Function? [ENDORSED]
Replies: 4
Views: 185

Re: Gibbs Free Energy: State Function? [ENDORSED]

The definition of a state function is a system that is not dependent on the pathway taken. Gibbs Free Energy is an example of a system where only the final and initial states have an effect on its value.. this is because the equation for Gibbs Free energy is ΔG=ΔH-TΔS, where (H and S) are state prop...
by Alejandra Rios 1L
Wed Jan 24, 2018 2:55 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Energy and matter?
Replies: 6
Views: 231

Re: Energy and matter?

We should take these into account for all systems, however there are differences between energy and matter when it comes to open/closed/isolated systems. For open systems we are able to transfer energy and matter. But for closed systems no matter can be transferred only energy can. Lastly, isolated ...
by Alejandra Rios 1L
Wed Jan 24, 2018 2:49 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Temperature
Replies: 3
Views: 103

Re: Temperature

When using the equation for Gibbs Free Energy it is appropriate to use Kelvin not any other unit of measurement.
by Alejandra Rios 1L
Wed Jan 24, 2018 2:40 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Lecture 1/24 (Wednesday) [ENDORSED]
Replies: 5
Views: 111

Re: Lecture 1/24 (Wednesday) [ENDORSED]

The derivations done by Dr. Lavelle in class today can be found in chapter 8. For further explanation, the equation is used to calculate reversible gas expansions. If you recall in last Friday's class, Dr. Lavelle derived w=-P∆V. In a similar manner, in today's class we derived the equation w=-nRT x...
by Alejandra Rios 1L
Thu Jan 18, 2018 3:28 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.23
Replies: 5
Views: 190

Re: 8.23

Using either kJ/C or J/C would be correct, however it might be easier to keep your answer in the same units as those given, this would prevent any miscalculations when making the conversion.
by Alejandra Rios 1L
Thu Jan 18, 2018 3:25 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: What does R stand for?
Replies: 13
Views: 573

Re: What does R stand for?

R is a constant which is used in ideal gas calculations. There are several values which you can use for R depending on what unit of pressure you are working with. These values will be given!
by Alejandra Rios 1L
Thu Jan 18, 2018 3:18 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: work vs heat
Replies: 4
Views: 147

Re: work vs heat

Although these two equations are both correct under specific conditions, these equations are derived from deltaU= q+w. deltaU=q is the equation we can use when no work is being done and has a value of 0, meanwhile deltaU=w is the equation when heat is zero, or not present. That being said, the work ...
by Alejandra Rios 1L
Thu Jan 11, 2018 11:22 am
Forum: Phase Changes & Related Calculations
Topic: Heat Capacity vs Specific Heat Capacity
Replies: 3
Views: 136

Re: Heat Capacity vs Specific Heat Capacity

Heat capacity tells you the heat supplied per change in temperature while heat capacity takes mass into account. When solving for heat capacity you would use C= q/ΔT, whereas when calculating for a specific heat capacity you would use Cs=C/m.. as noted, the equation for specific heat requires heat c...
by Alejandra Rios 1L
Thu Jan 11, 2018 10:47 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Equations
Replies: 6
Views: 215

Re: Equations

I think it would be good to know the general format of each equation, being ΔH = H(final) - H(initial), in order to be able to derive all equations such as: ΔH(vaporization) = H(vapor) - H(liquid) ΔH(fusion) = H(liquid) - H(solid) ... these two equations are also essential in being able to algebraic...
by Alejandra Rios 1L
Thu Jan 11, 2018 10:06 am
Forum: Phase Changes & Related Calculations
Topic: qp=deltaH
Replies: 8
Views: 344

Re: qp=deltaH

I do not think there will be a specific case where you are obligated to use "qp" instead of the deltaH notation but it is still important to understand the concept that they are equal to each other since it provides you with a definition of what the meaning of deltaH actually is.
by Alejandra Rios 1L
Thu Jan 11, 2018 9:52 am
Forum: Phase Changes & Related Calculations
Topic: chapter 8
Replies: 6
Views: 230

Re: chapter 8

You are correct. Dr. Lavelle mentioned that he would start with thermochemistry since it gives you an better understanding of the material in thermodynamics. For that reason, when looking at the textbook you should focus on the material towards the end of the chapter since it is switched in the book.

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