## Search found 56 matches

Sun Mar 15, 2020 8:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Athena
Replies: 34
Views: 2082

### Re: Athena

It's been an honor having you as a professor this quarter. Thank you for the work that you do and for sharing your passion for chemistry with us. I hope we cross paths again soon!
Sun Mar 15, 2020 7:59 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: final review slide 4
Replies: 4
Views: 173

### Re: final review slide 4

he finds the net production of gas because there are 3 mols of gas on the right side (products), 2 mols of gas on the left (reactants). Because this is a standard 1.00 mole reaction of O2, meaning the equation presented is what is occurring, you find the total production with a 3-2=1 mole of gas. t...
Sun Mar 15, 2020 6:54 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: final review slide 4
Replies: 4
Views: 173

### Re: final review slide 4

Actually nvm, I see my mistake now!
Sun Mar 15, 2020 6:53 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: final review slide 4
Replies: 4
Views: 173

### final review slide 4

How does Lavelle find that there is deltan=1 mole of gas when there's 3 moles of gas on the right side of the equation?
Sun Mar 15, 2020 6:48 am
Forum: First Order Reactions
Topic: Pseudo first order rxn
Replies: 5
Views: 143

### Pseudo first order rxn

Can someone explain exactly what a pseudo 1st order rxn is? The book was kind of confusing for me.
Sun Mar 15, 2020 6:46 am
Forum: Phase Changes & Related Calculations
Topic: Midterm Q4
Replies: 1
Views: 91

### Midterm Q4

(Really sorry if this is in the wrong section!)
When setting up the chemical equation, how do we know that Br- doesn't go in because it doesn't affect the ph? I guess my question is how do we know what affects the ph?
Sun Mar 15, 2020 6:20 am
Forum: Van't Hoff Equation
Topic: ln
Replies: 9
Views: 189

### Re: ln

it's e to the power of the other side! (x=e^lnx)
Sun Mar 15, 2020 6:17 am
Forum: Balancing Redox Reactions
Topic: oh
Replies: 11
Views: 268

### Re: oh

You would only add OH- to a reaction to balance the amount of H2O that was added (in general, for every H2O added, one OH- needs to be added).
Sun Mar 15, 2020 6:14 am
Forum: Balancing Redox Reactions
Topic: oxidation numbers
Replies: 4
Views: 148

### Re: oxidation numbers

I found a really good video explaining how to find them if you have the time to watch before Final real quick! I post the link below. Good luck! https://www.youtube.com/watch?v=-a2ckxhfDjQ
Sun Mar 15, 2020 6:12 am
Forum: Van't Hoff Equation
Topic: Celcius vs Kelvin for T1 and T2
Replies: 6
Views: 172

### Re: Celcius vs Kelvin for T1 and T2

I think it's safe to always use Kelvin unless told otherwise. Chemistry pretty much prefers Kelvin over other temperatures.
Sun Mar 15, 2020 6:10 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed system
Replies: 3
Views: 135

### Re: closed system

Because it doesn't allow for the exchange of matter. For example, let's say you have a shampoo bottle and it falls off the rack while you are taking a shower. Assuming the bottle is capped (closed system) the shampoo will not leak out of the bottle because the bottle doesn't allow that to happen!
Sun Mar 15, 2020 6:08 am
Forum: Administrative Questions and Class Announcements
Topic: Final exam structure
Replies: 2
Views: 155

### Re: Final exam structure

I would assume mostly free response but also a little bit of multiple choice, like how it was for the midterm.
Sun Mar 15, 2020 6:03 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: What was your favorite chem topic?
Replies: 24
Views: 526

### Re: What was your favorite chem topic?

Balancing chemical equations and chemical equilibrium!
Sat Mar 14, 2020 9:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating concentrations at equilibrium
Replies: 4
Views: 183

### Re: Calculating concentrations at equilibrium

WGaines_2E wrote:so the reaction looks like its gonna be COBr2 <> CO(g) + Br2(g)
you have the final concentration of CO
solve using ICE table

I figured it was an ice table question, but how would we solve if we weren't given K? Unless the og poster accidentally left K out?
Sat Mar 14, 2020 9:47 pm
Forum: General Rate Laws
Topic: 7A.15a
Replies: 4
Views: 108

### Re: 7A.15a

I think you have to compare two experiments where everything is constant except for one thing. For example, say for two experiments you have the same concentration of reactant A and B, but reactant C has a different concentration. You would focus on comparing those two experiments.
Sat Mar 14, 2020 6:52 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Calculating K
Replies: 4
Views: 116

### Re: Calculating K

Michelle Song 1I wrote:I don't think you can multiply both sides in k1 cause the left side of the Van't Hoff equation is ln(k2/k1) so you'd have to change that to ln(k2)-ln(k1) and add ln(k1) to both sides.

Sat Mar 14, 2020 6:51 pm
Forum: General Rate Laws
Topic: 7A.11( part b)
Replies: 1
Views: 80

### 7A.11( part b)

For part b I'm a bit confused. The book states that the reaction rate increases by a factor of 2 if H2 is doubled, however I remember the book saying that if you have a second order reaction and double the reactant, the rate increases by a factor of 4. PLease help!
Sat Mar 14, 2020 4:43 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Calculating K
Replies: 4
Views: 116

### Re: Calculating K

You would use the Van't Hoff equation! (ln K2/k1= delta Hr {1/T1-1/T2}); multiply both sides by k1 and remember that K=e ^lnK
Sat Mar 14, 2020 4:35 pm
Forum: General Rate Laws
Topic: 7A.3 Hw question
Replies: 1
Views: 46

### 7A.3 Hw question

For part b in 7A.3, wouldn't the answer be negative? The solution manual has it as positive 0.88 mol/l*s but I thought you would have to get ride of the negative on the other side since rate of formation is +delta [P]/delta t.
Sat Mar 14, 2020 2:01 pm
Forum: General Rate Laws
Topic: Hw 7A.13
Replies: 8
Views: 178

### Hw 7A.13

Can someone do a detailed walkthrough of how to do this problem? I keep getting the wrong answer :( 7A.13) In the reaction CH Br(aq) 1 OH2(aq) S CH OH(aq) 1 33 Br2(aq), when the OH2 concentration alone was doubled, the rate doubled; when the CH3Br concentration alone was increased by a factor of 1.2...
Fri Mar 13, 2020 9:39 pm
Forum: Administrative Questions and Class Announcements
Topic: "Open Book" Final?
Replies: 30
Views: 912

### Re: "Open Book" Final?

Does anyone know how the final is going to be given? Will it be a pdf that we have to print out and then take pictures of our answers or is it like through that respondus webcam thingie?
Thu Mar 05, 2020 11:27 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Hw 5.61
Replies: 1
Views: 28

### Hw 5.61

For letter f, how is it that adding water will not shift the reaction towards products? Is it because water is not apart of the eq constant?
Wed Mar 04, 2020 6:39 pm
Forum: Balancing Redox Reactions
Topic: Physical state
Replies: 6
Views: 119

### Physical state

How do we know the physical states of the elements after balancing the reaction?
Wed Mar 04, 2020 5:56 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number
Replies: 5
Views: 81

### Oxidation number

When balancing a redox reaction, how do we find the oxidation number? The book doesn't really say how, unless this was something that I was supposed to have learned before??
Wed Mar 04, 2020 1:19 pm
Forum: Van't Hoff Equation
Topic: Converting K back to Kc
Replies: 5
Views: 171

### Re: Converting K back to Kc

What's the equation needed to convert K back to Kc? I assumed you would just rearrange the Kc to K equation, but I wanted to ask just to be sure. aren't those the same Not according to the book :( Look at the very last part of section 5J.3, it talks about converting K to Kc when using Van't Hoff eq...
Tue Feb 25, 2020 5:36 pm
Forum: Van't Hoff Equation
Topic: Hw question 5J.15
Replies: 2
Views: 112

### Hw question 5J.15

For the first part of part a , I used the standard gibbs free energy equation and was able to correctly find the first K, but I'm using the Van't Hoff equation to find the second K and I keep getting one. I don't know if the book made the mistake or if I'm doing something wrong in my calculations (t...
Tue Feb 25, 2020 4:44 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5J.11 Halogen affect on K
Replies: 2
Views: 73

### 5J.11 Halogen affect on K

For question letter b, the book is gives a rxn ( X2 (g) --> 2 X(g) )and tells us that X is a halogen. How would we know how a halogen would affect the K? Because I don't remember halogens being discussed anywhere in that section (section 5J.11).
Tue Feb 25, 2020 4:09 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: HW question 5G.15
Replies: 4
Views: 121

### HW question 5G.15

I keep getting the wrong answer for this homework problem and I don't know what I am doing wrong. ( 5G.15 (a) Calculate the reaction Gibbs free energy of N2(g) 1 3 H2(g) S 2 NH3(g) when the partial pressures of N2, H2, and NH3 are 4.2 bar, 1.8 bar, and 21 bar, respectively, and the tempera- ture is ...
Tue Feb 25, 2020 3:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gas constant R
Replies: 5
Views: 77

### Gas constant R

When calculating the gibbs free energy using this equation (delta G = standard delta G + RTlnQ), how do you know which R to use?
Mon Feb 24, 2020 10:42 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free energy units
Replies: 4
Views: 104

### Gibbs Free energy units

Does the Gibbs free energy have to be reported in kJ per mol or can we report in J per mol?
Mon Feb 24, 2020 10:01 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff (Thermo vs. Kinetic approach)
Replies: 1
Views: 53

### Van't Hoff (Thermo vs. Kinetic approach)

Will we ever be asked to use the equations that are in the book that relate Temp to the EQ constant using kinetics vs. thermodynamics? To be a tad more specific, the equations in the yellow box that we are given before the book rearranges them into the Van't Hoff Equation.
Mon Feb 24, 2020 9:58 pm
Forum: Van't Hoff Equation
Topic: Converting K back to Kc
Replies: 5
Views: 171

### Re: Converting K back to Kc

Also, do you guys think points would be deducted on the test if we don't convert back to Kc after finding the new K?
Mon Feb 24, 2020 9:56 pm
Forum: Van't Hoff Equation
Topic: Converting K back to Kc
Replies: 5
Views: 171

### Converting K back to Kc

What's the equation needed to convert K back to Kc? I assumed you would just rearrange the Kc to K equation, but I wanted to ask just to be sure.
Fri Feb 14, 2020 9:21 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8502
Views: 1469590

### Re: Post All Chemistry Jokes Here

I have developed such a weird love for chemistry jokes, I love this thread lol I'll try to add some every now and then, here's the first one!

Man, I hate when I tell a chemistry joke and I don't get a...REACTION!

This was horrible, I'm so sorry!! :((((
Fri Feb 14, 2020 9:09 am
Forum: Student Social/Study Group
Topic: Midterm
Replies: 8
Views: 384

### Re: Midterm

Q8 was very similar to a homework problem on Entropy. It asked for the total, system, and surroundings entropy change for reversible vs irreversible expansion.
Fri Feb 14, 2020 8:56 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: midterm question// Concentration ratio [ENDORSED]
Replies: 9
Views: 253

### midterm question// Concentration ratio[ENDORSED]

I don't know if we all had the same midterm, but there was one question about concentrations and ph that I genuinely had no idea how to solve. It was about a molecule that would turn into a salt I think, and then i remember something about the ph of the stomach and the question asked us to find the ...
Fri Feb 14, 2020 8:52 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free energy concept
Replies: 16
Views: 275

### Gibbs Free energy concept

So this might sound bad especially since we just took our midterm on it, but I'm still having a little trouble understanding exactly what Gibbs free energy is? Like what does it tell us about a system or the surroundings and why is it an important concept to know for chemistry? I can do the equation...
Wed Feb 12, 2020 4:05 pm
Forum: Administrative Questions and Class Announcements
Replies: 67
Views: 2983

Can someone explain 2 D? For some reason I'm not getting the right answer for the reaction quotient :(
Mon Feb 10, 2020 10:38 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated vs Insulated
Replies: 3
Views: 110

### Isolated vs Insulated

Is there a difference between an isolated system and an insulated system?
Sun Feb 09, 2020 3:49 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Notes from class
Replies: 1
Views: 61

### Notes from class

Does anyone have the notes from class on Friday ( Jan 31st) and Monday (Feb 3)? I had a cold and couldn't make it to class. :(
Sun Feb 09, 2020 3:47 pm
Forum: Administrative Questions and Class Announcements
Topic: Step Up Sessions
Replies: 71
Views: 4572

### Re: Step Up Sessions

Does anyone know if there will be a Step-up session this Sunday at Covel? I know there's a midterm review going on but I couldn't make it :(
Thu Jan 30, 2020 5:14 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Using Kc Vs Kp
Replies: 22
Views: 245

### Re: Using Kc Vs Kp

If you are given concentrations, then you should use Kc. If you are given gases, then you should use Kp.
Thu Jan 30, 2020 5:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test #1// #5
Replies: 5
Views: 80

### Test #1// #5

Can someone explain how to do problem 5 on the test? (Problem: The pkb of fluoride is 10.8. A 0.12 M solution of hydrogen fluoride was made for silicon wafer processing. What is the pOH of this solution at equilibrium?)
Thu Jan 30, 2020 5:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test #1// #6
Replies: 2
Views: 43

### Test #1// #6

Can someone breakdown how to do problem #6? (Problem: The pH of a 0.10 M solution of hydrofluoric acid is 2.63. What are the Ka and % ionization?)
Thu Jan 30, 2020 5:02 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Reversible vs Irreversible formula
Replies: 4
Views: 107

### Reversible vs Irreversible formula

What key words should we look for in a word problem that would help us know whether the formula for work should be the reversible or irreversible one?
Thu Jan 30, 2020 5:01 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: State Property
Replies: 6
Views: 79

### Re: State Property

Internal energy (U) is a state property because the value doesn't change no matter the path you took to get there.
Thu Jan 30, 2020 4:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Negative pH
Replies: 9
Views: 68

### Re: Negative pH

I remember the book saying that it's possible to have a negative pH or a pH higher than 14, but that they wouldn't ask us questions outside the scope of a pH value from 1-14. Any acid that has a concentration of hydrogen ions with a molarity greater than 1 will likely be calculated to have a negativ...
Thu Jan 30, 2020 4:52 pm
Forum: Calculating Work of Expansion
Topic: Reversible Expansion
Replies: 1
Views: 41

### Reversible Expansion

Why are systems at equilibrium reversible?
Thu Jan 30, 2020 4:51 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated// Energy
Replies: 11
Views: 140

### Isolated// Energy

Can an isolated system have a change in energy?
Thu Jan 30, 2020 4:50 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard Form of molecule
Replies: 6
Views: 100

### Standard Form of molecule

How do we know that a molecule is in its "standard form"?
Thu Jan 30, 2020 4:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Liquids not in K
Replies: 1
Views: 35

### Solids and Liquids not in K

Why exactly aren't solids and liquids included in the eq constant?
Thu Jan 30, 2020 4:46 pm
Forum: Calculating the pH of Salt Solutions
Topic: Textbook problem 6b.3
Replies: 1
Views: 86

### Textbook problem 6b.3

The problem asks us to find both the desired ph and then then actual ph. I know to find the actual ph I would need to the amount of substance added (in moles), but how do I go about finding that?
Mon Jan 27, 2020 2:06 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard enthalpy of formation
Replies: 6
Views: 64

### Standard enthalpy of formation

Why exactly is the standard of formation of an element in its most stable form 0?
Sun Jan 26, 2020 7:24 pm
Forum: Bronsted Acids & Bases
Topic: Book example 6A.2
Replies: 1
Views: 111

### Book example 6A.2

When explaining how to find the concentration of OH- ions, the book wrote that 1 mol Ba(OH)2 ≏ 2 mol OH2. What does the ≏symbol mean?
Sun Jan 26, 2020 7:20 pm
Forum: Amphoteric Compounds
Topic: Amphoteric vs Amphiprotic
Replies: 13
Views: 468

### Re: Amphoteric vs Amphiprotic

Is it possible for a molecule to be both amphoretic and amphiprotic?
Thu Jan 23, 2020 12:59 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 6C.1
Replies: 2
Views: 43

### 6C.1

How do you write the chemical equation for a proton transfer?