## Search found 46 matches

Sun Mar 08, 2020 6:42 pm
Forum: Zero Order Reactions
Topic: Graphs
Replies: 13
Views: 604

### Re: Graphs

Does this still apply to winter 20!? Re: We won't be required to draw graphs but be able to interpret them.
Sun Mar 08, 2020 6:39 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: units of k
Replies: 9
Views: 166

### Re: units of k

Always go based on the order of the reaction:

If the reaction is zero-order, K has units of M/s
If the reaction is first-order, K has units of 1/s
If the reaction is second-order, K has units of 1/M.s
Sun Mar 08, 2020 6:37 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Energy Barrier
Replies: 4
Views: 66

### Re: Energy Barrier

I am confused about the same thing- could someone help us out???
Sun Mar 08, 2020 6:36 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: intermediate
Replies: 22
Views: 762

### Re: intermediate

The intermediate can't exist in the rate law because something was used to form it.
Sun Mar 08, 2020 6:35 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Replies: 73
Views: 4095

I think it's always good to find a friend who can attend different review sessions than you and then compare notes.
Tue Mar 03, 2020 12:32 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Exothermic vs. Endothermic
Replies: 10
Views: 529

### Re: Exothermic vs. Endothermic

An exothermic reaction- the activation energy is lower in the forward direction so if you heat up an exothermic reaction k reverse will increase which will result in a lower K and the reaction will favor reactants
Tue Mar 03, 2020 12:26 am
Forum: First Order Reactions
Topic: zero, first, and second order
Replies: 3
Views: 72

### Re: zero, first, and second order

Thanks for the helpful answer. But I'm still unclear why it's important to know these things and what they can help us learn about chemistry?
Tue Mar 03, 2020 12:25 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Replies: 73
Views: 4095

Who is Lyndon? Is he still a TA?
Tue Mar 03, 2020 12:23 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Order of compounds in cell diagram?
Replies: 5
Views: 103

### Re: Order of compounds in cell diagram?

For the solid on the far right or far left, do they have to be the same?
Tue Mar 03, 2020 12:19 am
Forum: Balancing Redox Reactions
Topic: 6K.1
Replies: 1
Views: 50

### Re: 6K.1

I also don't understand that- could someone explain?
Tue Feb 25, 2020 5:48 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 4
Views: 109

### Re: Test 2

I think it's likely it will focus on the thermodynamics stuff that wasn't on the midterm, beginning with the content taught during week 6. But obviously there can be overlap since it's all connected.
Tue Feb 25, 2020 5:47 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy and K
Replies: 5
Views: 126

### Re: Gibbs Free Energy and K

Gibbs energy is like a chemical potential that is reduced to its minimum when a system reaches eq. at constant pressure and temperature. Gibbs and K are related because they can tell us what is likely happen in a reaction.
Tue Feb 25, 2020 5:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cathode vs Anode
Replies: 6
Views: 122

### Re: Cathode vs Anode

The cathode is the one being reduced and the anode is the one being oxidized. The little pneumonic device I learned in high school to remember this was AN OX, RED COW. There's an ox (for anode and oxidation going together), and there's a red cow (for the pairing of reduction and cow for the c in cat...
Tue Feb 25, 2020 5:41 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: rust
Replies: 9
Views: 172

### Re: rust

Rusting itself is a redox reaction so I imagine LuValle could ask us a question revolving around an example of rusting.
Tue Feb 25, 2020 5:40 pm
Forum: Balancing Redox Reactions
Replies: 7
Views: 109

It's always good to start by determining how many electrons to add to each part of the reaction by calculating the overall charge of each side of the reaction.
Tue Feb 11, 2020 6:47 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat capacity
Replies: 3
Views: 60

### Re: Heat capacity

Thanks for all the helpful tips!

I also was wondering if everyone knew if we will ever be expected to know specific heat capacity values by heart? Or will we always be supplied with whatever we need?
Tue Feb 11, 2020 6:44 pm
Forum: Ideal Gases
Topic: Homework 3
Replies: 6
Views: 201

### Re: Homework 3

Speaking of- does anyone know where problems from homework #6 are supposed to come from? I think thermodynamics, but we didn't cover all of it yet- so I'm not sure how to go about it.
Tue Feb 11, 2020 6:43 pm
Forum: Calculating Work of Expansion
Topic: Midterm equation sheet
Replies: 16
Views: 225

### Re: Midterm equation sheet

Yes, it's the same.

I often find it helpful to cross out the equations we don't know anything about- so the equations sheet is less overwhelming.
Tue Feb 11, 2020 6:41 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm Material
Replies: 10
Views: 168

### Re: Midterm Material

I think basically the general ideas of Gibbes free energy and the central equation is what's expected (only the stuff from the first page of the outline on thermodynamics)
Tue Feb 11, 2020 6:38 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: ∆G, ∆H, ∆S
Replies: 6
Views: 148

### Re: ∆G, ∆H, ∆S

They relate because they can tell you lots of things about if a reaction will occur spontaneously and if it's favorable. It is expected that how this could be presented on a test would be if you were given all or some of these terms and asked to deduce overall conclusions about the system.
Wed Feb 05, 2020 9:39 pm
Forum: Phase Changes & Related Calculations
Topic: Relevance of Phase Changes
Replies: 9
Views: 83

### Re: Relevance of Phase Changes

I think also phase change helps orient what values will be positive and negative. You need to take phase changes into account when calculating the change of enthalpy in a reaction (the calculations we use assume that all the reactants and products are gases).
Wed Feb 05, 2020 9:37 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: ∆U and ∆H
Replies: 6
Views: 92

### Re: ∆U and ∆H

Delta U and delta H are interlocked cause the change in internal energy equals the change in enthalpy plus the work done on the system (this is one of the important equations in this unit).
Wed Feb 05, 2020 9:36 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Topics on the Midterm
Replies: 22
Views: 341

### Re: Topics on the Midterm

Everything for topics 1-4. I believe he said that he will begin and finish covering Gibbs free energy in the lecture this coming Wednesday and Friday. Does anyone know if we will be learning new things next week on Monday and Wednesday?
Wed Feb 05, 2020 9:33 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Significance of open, closed, isolated
Replies: 11
Views: 343

### Re: Significance of open, closed, isolated

Exactly- it helps you determine which variables are constant in an equation (and can thus be substituted for 0s).
Wed Feb 05, 2020 9:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Phase change
Replies: 20
Views: 212

### Re: Phase change

A positive delta H means energy is put in, which makes it endothermic, which is what is necessary to break the bonds that holds a solid together into a liquid. That's why the change in enthalpy is positive!
Sun Jan 26, 2020 7:16 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: bond v. standard
Replies: 5
Views: 64

### Re: bond v. standard

Yea so essentially: standard enthalpies are the change of enthalpy during the formation of 1 M of the substance from its elements needed to make it, but bond enthalpies are the amount of energy required to break bonds. How I remember it is bond is B for break, and standard is s for synthesize.
Sun Jan 26, 2020 7:13 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: specific heat
Replies: 3
Views: 327

### Re: specific heat

Yes- they will be specific values. Also, I believe it's safe to assume that we will either be given the specific heat or be asked to calculate it (when we have everything else given).
Sun Jan 26, 2020 7:11 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Lewis Structures
Replies: 4
Views: 53

### Re: Lewis Structures

I find that lewis structure is really about practice. I usually like to watch youtube videos and follow along and practice!
Sun Jan 26, 2020 7:10 pm
Forum: Phase Changes & Related Calculations
Topic: Phase changes: endothermic vs exothermic
Replies: 12
Views: 197

### Re: Phase changes: endothermic vs exothermic

So essentially: endo is adding energy/heat, and exo is when heat/energy is released
Sun Jan 26, 2020 7:07 pm
Forum: Phase Changes & Related Calculations
Topic: Why does steam cause burns?
Replies: 29
Views: 315

### Re: Why does steam cause burns?

Would anyone be able to describe the diagram you all are referencing? I was sick and unfortunately missed that lecture :/
Tue Jan 21, 2020 6:21 pm
Forum: Student Social/Study Group
Topic: Curve?
Replies: 50
Views: 1903

### Re: Curve?

Since it depends on class average at the end of the quarter- does that sort of mean you can't calculate your grade at all throughout the quarter?
Tue Jan 21, 2020 6:20 pm
Forum: Administrative Questions and Class Announcements
Topic: Test One Content
Replies: 6
Views: 115

### Re: Test One Content

Is the only requirement for the calculator that it cannot be graphing?
Tue Jan 21, 2020 6:19 pm
Forum: Administrative Questions and Class Announcements
Replies: 8
Views: 200

Just checking- the five posts are due basically before your scheduled discussion section for the week?
Tue Jan 21, 2020 6:18 pm
Forum: Administrative Questions and Class Announcements
Topic: Discussion
Replies: 8
Views: 87

### Re: Discussion

I would think if you had to miss a discussion one week you could email your TA and ask to give into your HW during a lecture during that week. Just an idea.
Tue Jan 21, 2020 6:16 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 1 Study Guide/Worksheet
Replies: 5
Views: 661

### Re: Test 1 Study Guide/Worksheet

I also don't understand why that one is 2 sig figs. Is there a place I could get good review on sig figs?
Thu Jan 16, 2020 8:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: H3O+
Replies: 4
Views: 30

### Re: H3O+

So essentially H+ and H3O+ are the same things just expressed differently?
Thu Jan 16, 2020 8:50 pm
Forum: Ideal Gases
Topic: ph
Replies: 10
Views: 169

### Re: ph

The way I like to think of it is it can lie outside of the 0 to 14 range, but pH + pOH must equal 14 when added together.
Thu Jan 16, 2020 8:49 pm
Forum: Ideal Gases
Topic: mole fraction
Replies: 4
Views: 45

### Re: mole fraction

I understand the posts before this but what exactly is the definition of partial pressure? Just the fraction that a certain gas takes up? I am making it more complicated than it is?
Thu Jan 16, 2020 8:45 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Replies: 3
Views: 54

I've found that first simplifying the denominator is the key to making these problems go smoothly. Always start with that.
Thu Jan 16, 2020 8:42 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 337
Views: 139500

### Re: Saying Thank You to Dr. Lavelle

I know it's early on in the quarter, but I can already tell that Dr. Lavelle is going to make a significant impact on my time at UCLA, specifically this quarter. He just makes the material so digestible and I truly appreciate his approach. He also seems to WANT us to succeed. Thank you already!
Thu Jan 16, 2020 8:38 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 226
Views: 35948

### Re: Final Jitters

I think it's super helpful to get to the exam site early to habituate yourself to the room. It can be off-putting to be in a new room without being familiar with it. I usually go an hour early to sit just scrolling through my phone or meditating. It makes when the test gets put out less scary.
Thu Jan 09, 2020 8:07 pm
Forum: Ideal Gases
Topic: How Plausible is Ideal Gas?
Replies: 1
Views: 32

### How Plausible is Ideal Gas?

I understand that we use the ideal gas law for calculations, but how many gases actually behave in an ideal manner? How realistic are the calculations we get and is it mostly just theoretical or based on empirical data?
Thu Jan 09, 2020 8:01 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure's Effect on Equilibrium
Replies: 6
Views: 102

### Re: Pressure's Effect on Equilibrium

What exactly defines an Inert gas? I understand the posts above except for this.
Thu Jan 09, 2020 7:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Why is K unitless?
Replies: 10
Views: 121

### Re: Why is K unitless?

K is y a ratio (between products and reactants) and so it does not have units- but so does this mean that all ratios we use in this class will be unitless? Is it safe to apply this rule widely?
Thu Jan 09, 2020 7:58 pm
Forum: Ideal Gases
Topic: converting Kc to Kp
Replies: 13
Views: 146

### Re: converting Kc to Kp

What exactly is the difference between Kc and Kp? I know (or think) they are equilibria constants but what do they individually represent?
Thu Jan 09, 2020 7:56 pm
Forum: Ideal Gases
Topic: Understanding Q
Replies: 13
Views: 114

### Re: Understanding Q

I understand the fact that you omit solids and liquids when calculating the equilibrium constant, but why? What's the logic behind it?