Search found 99 matches

by Ariana de Souza 4C
Sat Mar 18, 2017 10:52 am
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 202
Views: 76454

Re: Saying Thank You to Dr. Lavelle

Hey Dr. Lavelle, Thank you SO much for everything you do for 14A/B students! I cannot tell you how many times I've gone to peer review learning sessions, ta meetings, office hours -- they were incredibly helpful, and I'm so thankful that you and all of your ta's and ua's put that time in. You really...
by Ariana de Souza 4C
Sat Mar 18, 2017 10:28 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Standard Conditions and Temperature
Replies: 5
Views: 603

Re: Standard Conditions and Temperature

But then in the 2016 final problem 2A, we use the standard gibbs free energy and use this equation -- -- with the standard gibbs free energy when T=1943. Why can we do that?
by Ariana de Souza 4C
Fri Mar 17, 2017 10:10 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Standard Conditions and Temperature
Replies: 5
Views: 603

Standard Conditions and Temperature

Hello! I just wanted to get something cleared up -- what is the relationship between the standard condition of G and H and S and temperature? We can still say that it is (delta G)^o if the temperature isn't 298 K, right? And all we need for standard conditions is the pressure to be 1 atm and for the...
by Ariana de Souza 4C
Thu Mar 16, 2017 10:04 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Practice Problems
Replies: 16
Views: 1784

Re: Practice Problems

If you are referring to the first problem set, because it places the largest substituents anti to each other. But can't you have the largest groups still anti each other but then on the left side of the newman projection have CH3 and H and then on teh right side have CH3 and H so that one side does...
by Ariana de Souza 4C
Thu Mar 16, 2017 9:55 pm
Forum: *Alcohols
Topic: 2013 final Q6B
Replies: 2
Views: 563

Re: 2013 final Q6B

you don't need to know the common names -- you have the IUPAC names in that same order, so you know the IUPAC name for the respective common name, and can just use that for identifying the structure
by Ariana de Souza 4C
Tue Mar 07, 2017 10:31 am
Forum: Administrative Questions and Class Announcements
Topic: Quiz 3 Winter 2017
Replies: 183
Views: 15504

Re: Quiz 3 Winter 2017

for #1, why do we need "iso" infant of propyl? wouldn't the 4- signify the branching? No, because the 4 signifies from what carbon on the MAIN BRANCH you're substituent is on. WIthin the substituent itself, though, there is branching, and that's why you'd either say iso-propyl (common nam...
by Ariana de Souza 4C
Mon Mar 06, 2017 10:52 pm
Forum: *Cycloalkanes
Topic: Tert- Naming
Replies: 4
Views: 718

Re: Tert- Naming

when we name something, for example, "tert butyl" does the t count in the alphabetical order? or does it not? I thought it would, since it's a common name, and for other common names like isopropyl or neopentyl, we include the prefix for alphabetic consideration? And for number 1.17 in th...
by Ariana de Souza 4C
Mon Mar 06, 2017 10:46 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 3 Winter 2017
Replies: 183
Views: 15504

Re: Quiz 3 Winter 2017

For the first question, how do you know it is 4- isopropyldecane? I thought that it was just 4-propyldecane Can someone please address this? Why do we need the "iso" prefix? Isn't it just a propyl functional group attached to the 4th carbon of a decane compound? The reason we can't just s...
by Ariana de Souza 4C
Mon Mar 06, 2017 10:41 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 3 Winter 2017
Replies: 183
Views: 15504

Re: Quiz 3 Winter 2017

Can someone help me with #3 I don't understand how both of them are nucleophiles? Are you referring to #6? Nucleophiles are species rich in electrons. For the benzene ring, this electron richness comes from its double bonds. For CH_{3}OCH_{3} the oxygen in the center of the compound can only be att...
by Ariana de Souza 4C
Sun Mar 05, 2017 4:24 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 3 Winter 2017
Replies: 183
Views: 15504

Re: Quiz 3 Winter 2017

Will we be responsible for knowing how to solve questions 5-8 on the practice quiz #3 even though we didn't go over that kind of thing in lecture? we went through numbers 5-8 in class.. the only thing we havent is number seven when it says 2-butene. that just means you have a butene and then your d...
by Ariana de Souza 4C
Sun Mar 05, 2017 4:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 3 Winter 2017
Replies: 183
Views: 15504

Re: Quiz 3 Winter 2017

For number 1, I wrote down 4-isopropyldecane as my answer, but I don't understand why it can also be 4-(1-methleythyl) decane the second answer would be if you're writing it by IUPAC rules. you can see the isopropyl as a long ethane (that's your longest chain) with a methane coming out of the first...
by Ariana de Souza 4C
Sun Mar 05, 2017 4:16 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 3 Winter 2017
Replies: 183
Views: 15504

Re: Quiz 3 Winter 2017

Jocelyn_Dao_2N wrote:Hi! Why is the answer for number 4, 4-butyl-1,2-dimethylcyclohexane and not 1,2-dimethyl,4-butylcyclohexane?

When naming a compound, do the lower numbers do first?


remember that you have to do it alphabetically. butyl comes before methyl
by Ariana de Souza 4C
Sat Mar 04, 2017 3:13 pm
Forum: *Cycloalkanes
Topic: Tert- Naming
Replies: 4
Views: 718

Re: Tert- Naming

when we name something, for example, "tert butyl" does the t count in the alphabetical order? or does it not? I thought it would, since it's a common name, and for other common names like isopropyl or neopentyl, we include the prefix for alphabetic consideration? And for number 1.17 in the...
by Ariana de Souza 4C
Sat Mar 04, 2017 3:11 pm
Forum: *Cycloalkanes
Topic: HW CH1 #16 [ENDORSED]
Replies: 1
Views: 321

Re: HW CH1 #16 [ENDORSED]

so it isn't equivalent numbering. you have either 2, 1, 1, or 2, 2, 1. you choose the first because 1 < 2 and you have more 1's in the first one than you have in the second one.
by Ariana de Souza 4C
Fri Mar 03, 2017 6:37 pm
Forum: *Alkenes
Topic: 1.12 c question
Replies: 2
Views: 257

Re: 1.12 c question

oh! thanks !!
by Ariana de Souza 4C
Fri Mar 03, 2017 6:30 pm
Forum: *Alkenes
Topic: 1.12 c question
Replies: 2
Views: 257

1.12 c question

Hey guys,
im feeling like this is a dumb question, but for 1.12 c, why is it 3,4,4 - trimethyl-2-pentene and not 2,2,3 trimethyl-3-pentene ?
thanks :)
by Ariana de Souza 4C
Thu Mar 02, 2017 5:58 pm
Forum: *Organic Reaction Mechanisms in General
Topic: reaction profile delta g second transition state
Replies: 1
Views: 245

reaction profile delta g second transition state

so on page 157 in the green o chem book, it says that we should refer to the delta G double dagger of the second transition state not in reference to the intermediate, but in reference to the reactants. so you would have the delta G be from the reactants to the energy of the second transition state....
by Ariana de Souza 4C
Thu Mar 02, 2017 5:52 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Delta G Double Dagger, Delta H Double Dagger, Delta S Double Dagger
Replies: 3
Views: 2393

Re: Delta G Double Dagger, Delta H Double Dagger, Delta S Double Dagger

And I'm pretty sure you have delta S as negative because you're making the molecule into one particular orientation for it to be a transition state, so there is a decrease in entropy. I don't know why you would have a positive delta S though...
by Ariana de Souza 4C
Mon Feb 20, 2017 4:48 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 2 Winter 2017
Replies: 160
Views: 14975

Re: Quiz 2 Winter 2017

If the answer to #2 if false, what other possible units can be used to signify rate constant? It depends on what order the reaction is. you can just check this with the rate equations. ZERO ORDER: Rate=k the units of the rate are M/s so k must be M/s too for zero order reactions FIRST ORDER: Rate =...
by Ariana de Souza 4C
Mon Feb 20, 2017 4:46 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 2 Winter 2017
Replies: 160
Views: 14975

Re: Quiz 2 Winter 2017

Can someone explain the graphing part of question 4 on the practice quiz? It tells you that you have a graph where you're plotting the natural log of NOBr against time, and you get a straight line. on page 63 in the course reader, you can see that that's basically how you know that the reaction is ...
by Ariana de Souza 4C
Sun Feb 19, 2017 6:21 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Steady State Approach [ENDORSED]
Replies: 3
Views: 443

Re: Steady State Approach [ENDORSED]

but the book on page 634 goes over a steady state approximation for a reaction with a fast first step and a slow second step... whats going on there?
by Ariana de Souza 4C
Sun Feb 19, 2017 5:47 pm
Forum: Zero Order Reactions
Topic: Zero Order and k [ENDORSED]
Replies: 2
Views: 424

Re: Zero Order and k [ENDORSED]

but the slope is -k. So wouldn't k have to be positive, for there to be a negative slope?
by Ariana de Souza 4C
Sun Feb 19, 2017 5:38 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 2 Winter 2017
Replies: 160
Views: 14975

Re: Quiz 2 Winter 2017

Could someone explain to me how to do #6? So this one you need to split into two problems. The first step will be to determine what k is. 1) you have your initial concentration (0.95 M) and your final concentration (0.44 M) and the time it takes (11 minutes) you use your equation 1/(At) - 1/(A0) = ...
by Ariana de Souza 4C
Sun Feb 19, 2017 4:40 pm
Forum: General Rate Laws
Topic: products in rate law equation
Replies: 4
Views: 451

products in rate law equation

Hey guys in the course reader on page 60, it says that we're only going to be focusing on initial rates that are a function of only reactant concentration. but in the textbook, on page 621, it says that rate laws may depend on the concentrations of prouctsa s well as those of reactants. It uses O3 -...
by Ariana de Souza 4C
Sun Feb 19, 2017 4:04 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 2 Winter 2017
Replies: 160
Views: 14975

Re: Quiz 2 Winter 2017

For rxn mechanisms will we have to infer the intermediate for a rxn or will it be given to us? Pretty sure the mechanism will be given to us. The intermediate will be the compound that is in the products of the first reaction and in the reactants of the second, and so will be canceled out -- it sho...
by Ariana de Souza 4C
Sun Feb 19, 2017 3:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 2 Winter 2017
Replies: 160
Views: 14975

Re: Quiz 2 Winter 2017

for number 8, is it okay if we express it in seconds, since the question gave the rate constant in seconds?
Additionally, do we need to know how to do numbers 5, 9, and 11 ? They all have to do with enzymes and the arrhenius equation, and i thought we didn't have to know that
by Ariana de Souza 4C
Sat Feb 18, 2017 1:37 pm
Forum: Second Order Reactions
Topic: homework problem #35
Replies: 4
Views: 579

Re: homework problem #35

So it's because the equation for the second order half lives include the concentration of the initial substance? Then the reason we can multiply half lives for problem 15.27 is because, there, it's talking about a first order reaction, which only concerns the rate constant? For reference, 15.27 : &q...
by Ariana de Souza 4C
Wed Feb 15, 2017 3:10 pm
Forum: Administrative Questions and Class Announcements
Topic: Sig figs for ln
Replies: 1
Views: 470

Sig figs for ln

Hey everyone
Not sure if this has been asked before (it probably has) but does the mantissa rule still apply for natural logs?
And do we use that rule whenever we need to use an equation that uses a natural log? Does the rule change when we have to do e^x to get rid of the natural log?
Thanks
by Ariana de Souza 4C
Mon Feb 13, 2017 1:45 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: 2014 Midterm
Replies: 5
Views: 547

Re: 2014 Midterm

at the end of the problem, how come we take the square root of K? it says
Ka= sqrt(K)
by Ariana de Souza 4C
Fri Feb 10, 2017 7:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Potential vs Standard Cell Potential
Replies: 2
Views: 339

Re: Cell Potential vs Standard Cell Potential

standard e potential (E^o) is when you are at standard conditions, so when you know that everything is at 1 molar. when you're just asked for cell potential, it's probably not at standard conditions -- meaning you probably have to use the nernst equation, because it's a concentration cell. hope that...
by Ariana de Souza 4C
Fri Feb 10, 2017 7:29 pm
Forum: Administrative Questions and Class Announcements
Topic: Galvanic Cells
Replies: 1
Views: 266

Re: Galvanic Cells

You separate them with a comma when they are in the same state, and with a "I" when it's in different states. for example: 14.13 a) Zn (s) I Zn 2+ (aq) II Ni 2+ (aq) I Ni (s) vs. b) Pt (s) I I- (aq) I I2(s) II Ce 4+ (aq), Ce 3+ (aq) II Pt both Ce's are aqueous, so we separate them with a c...
by Ariana de Souza 4C
Fri Feb 10, 2017 7:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Inert Electrodes
Replies: 2
Views: 334

Re: Inert Electrodes

In the same vein as the question posted, in the course reader, we put an inert conductor on only one side of this diagram 2Fe 3+ (aq) + Cu (s) --> Cu 2+ (aq) + 2 Fe 2+ (aq Cu (s) I Cu 2+ (aq) II Fe 3+ (aq). Fe 2+ (aq) I Pt(s) I'm assuming this is because the left side of the equation has a solid, bu...
by Ariana de Souza 4C
Mon Feb 06, 2017 12:43 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Ch 14 q 55
Replies: 2
Views: 369

Ch 14 q 55

We are supposed to come up with the anode and cathode reaction for 1 M NiSo4 solution electrolyzed. When it comes to choosing the anode, the solution manual says to choose the oxidation reaction with the most negative reduction potential. so why did we choose 2H20 --> O2 + 4H+ +4e- with an standard ...
by Ariana de Souza 4C
Thu Feb 02, 2017 5:20 pm
Forum: Balancing Redox Reactions
Topic: 14.5 a
Replies: 2
Views: 306

Re: 14.5 a

Oh! That does make sense, thank you!
by Ariana de Souza 4C
Wed Feb 01, 2017 8:09 pm
Forum: Balancing Redox Reactions
Topic: 14.5 a
Replies: 2
Views: 306

14.5 a

a) O3 + Br(-) --> O2 + BrO3 (-) for the oxidation reaction, when balancing out the hydrogens, the solution manual goes from 3 H20 + Br(-) --> BrO3(-) to 6 OH (-) + 3 H2O + Br(-) --> BrO3(-) + 6H2O I don't understand why they are adding the hydroxide and the water to the equation instead of balancing...
by Ariana de Souza 4C
Thu Jan 26, 2017 11:08 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Quiz 1 Prep Question 3
Replies: 4
Views: 584

Re: Quiz 1 Prep Question 3

right, because q=-w. But then using that equation, we don't factor in pressure. Do you ignore the values of pressure that are given in the problem?
by Ariana de Souza 4C
Thu Jan 26, 2017 10:21 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Quiz 1 Prep Question 3
Replies: 4
Views: 584

Quiz 1 Prep Question 3

IF 2 mol of an ideal gas at 300 K and 3 atm expands isothermally and reversibly from 6 L to 18 L and has a final pressure of 1.20 atm, what is w, q, and delta U?

What do we do if both volume and pressure are changing? What equations should I be considering? Thanks
by Ariana de Souza 4C
Wed Jan 25, 2017 10:26 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Quiz 1 Prep, #8
Replies: 4
Views: 445

Re: Quiz 1 Prep, #8

So I get that from the table. But from the math, are we supposed to assume that since we get a negative K value, it's impossible? And from that should we know that it would never be spontaneous? And additionally, when we get values for T, is it always that when T is greater than that value, it's spo...
by Ariana de Souza 4C
Wed Jan 25, 2017 11:29 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Chapter 9 Q 47
Replies: 1
Views: 365

Chapter 9 Q 47

Initially a sample of ideal gas at 323 K occupies 1.67 L at 4.95 atm. the gas is allowed to expand to 19.44 L. a) it expands isothermally, reversible expansion b) isothermally, IRREVERSIBLE free expansion calculate delta S total delta S, and delta S surroundings for each pathway I understand a, but ...
by Ariana de Souza 4C
Thu Jan 19, 2017 8:17 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Help on Problem 8.99 [ENDORSED]
Replies: 4
Views: 679

Re: Help on Problem 8.99 [ENDORSED]

this is all so incredibly detailed, and bless your soul, but one question-- ΔH*rxn = [1mol(ΔH*f(H2)) + 1mol(ΔH*f(Zn2+))] - [2mol(ΔH*f(H+)) + 1mol(ΔH*f(Zn))] ΔH*rxn = [1mol(ΔH*f(0)) + 1mol(ΔH*f(-153.89KJ/mol))] - [2mol(ΔH*f(0)) + 1mol(ΔH*f(0))] ΔH*rxn = -153.89KJ how come you have an enthalpy of form...
by Ariana de Souza 4C
Thu Jan 19, 2017 6:53 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Help on Problem 8.99 [ENDORSED]
Replies: 4
Views: 679

Re: Help on Problem 8.99 [ENDORSED]

I don't get that problem either, but can you explain why you need to find the limiting reactant and how you then find the enthalpy?
by Ariana de Souza 4C
Wed Jan 18, 2017 2:13 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sign change ch 8 q 51 [ENDORSED]
Replies: 4
Views: 606

Re: Sign change ch 8 q 51 [ENDORSED]

and in that same vein of "Releasting" vs "absorbing" -- for 8.99, the solution manual uses the specific heat capacity of water (we're assuming that HCL has the same specific heat capacity as water) as -4.184. I'm not really clear as to why we are using negative? 8. 99) a piece of...
by Ariana de Souza 4C
Wed Jan 18, 2017 1:41 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Ch 8 Q 53
Replies: 4
Views: 419

Re: Ch 8 Q 53

yes, thanks so much!
by Ariana de Souza 4C
Wed Jan 18, 2017 1:36 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sign change ch 8 q 51 [ENDORSED]
Replies: 4
Views: 606

Re: Sign change ch 8 q 51 [ENDORSED]

Ohhhhhhhhhhhhhhhhhhhhhhhhh. That makes sense. Thank you hahah
by Ariana de Souza 4C
Mon Jan 16, 2017 3:34 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sign change ch 8 q 51 [ENDORSED]
Replies: 4
Views: 606

Sign change ch 8 q 51 [ENDORSED]

8.51) the enthalpy of formation of TNT is -67 kj?mol and the density is 1.65 g/cm^3. explore its potential as a rocket fuel by calculating its enthalpy density (enthalpy released per liter) for the reaction 4 C7H5N3O6(s) + 21 O2 (g) --> 28 CO2(g) + 10 H2O (G) + 6 N2(g) The energy released per mole o...
by Ariana de Souza 4C
Mon Jan 16, 2017 3:28 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Ch 8 Q 53
Replies: 4
Views: 419

Re: Ch 8 Q 53

Yeah, it does! I appreciate the explanation. So when you're doing the math part, you're doing --

q(reaction) = -q(calorimeter)
q(Reaction)= -q*C*deltaT
so are you calculating the heat of the reaction then by saying it's the opposite of the heat of the calorimeter?
by Ariana de Souza 4C
Sun Jan 15, 2017 3:38 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Ch 8 Q 53
Replies: 4
Views: 419

Ch 8 Q 53

CO(g) + H20(g) --> CO2(g) + H2(g) reaction of 1.4 g of CO in a bomb calorimeter causes the temp to go from 22.113 C to 22.799 C. The calorimeter assembly is known to have a total heat capacity of 3.00 kJ/C b) calculate the internal energy change, delta U, for the reaction of 1 mol CO So the solution...
by Ariana de Souza 4C
Thu Jan 12, 2017 11:13 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Help on HW 8.57
Replies: 4
Views: 571

Re: Help on HW 8.57

how do you know to write those three equations from what they give you? Sorry if this is a silly question
by Ariana de Souza 4C
Wed Jan 11, 2017 12:26 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Ch 8 Q 25
Replies: 1
Views: 384

Ch 8 Q 25

I dont understand how the solution manual does this question. A constant volume calorimeter was calibrated by carrying out a reaction known to release 3.5 kJ of heat in 0.2 L of solution in the calorimeter, resulting in a temperature rise of 7.32 C. In a subsequent experiment, 100.00 mL of 0.2 M HBr...
by Ariana de Souza 4C
Wed Jan 11, 2017 12:25 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Ch 8 Q 25
Replies: 1
Views: 321

Ch 8 Q 25

I dont understand how the solution manual does this question. A constant volume calorimeter was calibrated by carrying out a reaction known to release 3.5 kJ of heat in 0.2 L of solution in the calorimeter, resulting in a temperature rise of 7.32 C. In a subsequent experiment, 100.00 mL of 0.2 M HBr...
by Ariana de Souza 4C
Thu Dec 01, 2016 3:45 pm
Forum: *Titrations & Titration Calculations
Topic: Hwk 13.29
Replies: 5
Views: 765

Re: Hwk 13.29

you're right -- must have missed that. sorry! then all the calculations after that are off by a bit -- sorry again
by Ariana de Souza 4C
Wed Nov 30, 2016 7:48 pm
Forum: *Titrations & Titration Calculations
Topic: Hwk 13.29
Replies: 5
Views: 765

Re: Hwk 13.29

dude ive been doing this problem for around an hour and i finally got it. so first you find the moles of HCl (Because it's at the stoich point, and since NaOH is impure, we're gonna use HCl to find out NaOH) 0.0695 mol HCl x 0.03420 L = 0.0023769 moles HCl so that means that there are 0.0023769 mole...
by Ariana de Souza 4C
Wed Nov 30, 2016 6:26 pm
Forum: Calculating the pH of Salt Solutions
Topic: chapter 13 q 23
Replies: 1
Views: 326

Re: chapter 13 q 23

okay i've kind of gotten it but am still confused a little about how to get the final point so for the initial point.. Initial Point -- it's only gonna be NaOH (no HCL added yet) so pOH= -log(0.01M)=2 pH=14-2=12 and then Stoich Point-- moles NaOH=molesHCl pH is gonna be 7 (Strong base and strong aci...
by Ariana de Souza 4C
Tue Nov 29, 2016 7:57 pm
Forum: Calculating the pH of Salt Solutions
Topic: chapter 13 q 23
Replies: 1
Views: 326

chapter 13 q 23

hey im having a lot of trouble with this question. I looked at the textbook explanation for a similar problem but I'm extremely confused "a) Sketch the titration curve for the titration of 5 mL 0.020 M NaOH with 0.005 M HCl, indicating the pH of the initial and final solutions and the pH at the...
by Ariana de Souza 4C
Tue Nov 29, 2016 6:48 pm
Forum: Calculating the pH of Salt Solutions
Topic: Ch 13 Q 21 a
Replies: 2
Views: 349

Re: Ch 13 Q 21 a

oh! I see. thanks so much!
by Ariana de Souza 4C
Tue Nov 29, 2016 6:01 pm
Forum: Calculating the pH of Salt Solutions
Topic: Ch 13 Q 21 a
Replies: 2
Views: 349

Ch 13 Q 21 a

Hiya
so for question 21 a, the solution manual does something and i keep getting the wrong answer.
log ([CO3 2-]/[HCO3-]) = 0.75
[CO3 2-]/[HCO3-]=5.6
but when i take the antilog of 0.75 (which is (10^(-0.75))) and I keep getting 0.1778!! I don't know where 5.6 comes from??
by Ariana de Souza 4C
Mon Nov 28, 2016 8:52 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: 13.11
Replies: 1
Views: 277

Re: 13.11

I think (I'm not sure, someone please correct me if im wrong) that it's because you're adding OH, right? So that's going to react with the acid, which is CH3COOH. That is going to cause the forward reaction to occur, which would decrease thea mount of CH3COOH and increase theamount of CH3COO-. And b...
by Ariana de Souza 4C
Mon Nov 28, 2016 8:13 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: 13.3 Henderson-Hasselbalch Equation Logs
Replies: 2
Views: 733

Re: 13.3 Henderson-Hasselbalch Equation Logs

I also have a question on this part.
I have (x*y)/(2x)=3.02x10^(-4)
This is probably a simple mistake on my part but how come you end up with 2*Ka?? the x's don't cancel out -- so how does that math work?
by Ariana de Souza 4C
Fri Nov 25, 2016 11:01 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Chapter 11 Q 89
Replies: 3
Views: 444

Re: Chapter 11 Q 89

ohhh, i see!! Thanks!!
by Ariana de Souza 4C
Fri Nov 25, 2016 10:36 pm
Forum: Calculating the pH of Salt Solutions
Topic: ch 12 q 69 b [ENDORSED]
Replies: 1
Views: 302

ch 12 q 69 b [ENDORSED]

Hiya
So question 69 b) asks for the pH of 0.055 M AlCl3. The solutions manual then lsits this chemical equation
Al(H20)6 (3+) + H20 <--> H3O + Al(H2O)5 OH)(2+)
I am just completely lost as to where this equation came from. Thanks!!
by Ariana de Souza 4C
Wed Nov 23, 2016 2:05 pm
Forum: Lewis Acids & Bases
Topic: strong or weak acid
Replies: 6
Views: 724

Re: strong or weak acid

So in the course reader it says that alkali metals and alkali earth metals form hydroxides and oxides that make strong bases. but then it shows this equation --- CaO +H2O <--> Ca + 2OH- wouldn't it not be <---> because that shows equilibrium, but just --> if it's a strong base?? Since it's dissociat...
by Ariana de Souza 4C
Mon Nov 21, 2016 6:24 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Why when given Ka = weak acid
Replies: 7
Views: 761

Re: Why when given Ka = weak acid

but how come, then, when we are given a table of Ka values, we can choose the strongest acid based on the biggest Ka value? Why is there a Ka value then for a strong acid?
by Ariana de Souza 4C
Mon Nov 21, 2016 5:40 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Why when given Ka = weak acid
Replies: 7
Views: 761

Why when given Ka = weak acid

I'm confused about why when a problem gives you Ka, you know it's going to be a weak acid. Why do we know this? Thanks
by Ariana de Souza 4C
Thu Nov 17, 2016 8:15 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Chapter 11 Q 89
Replies: 3
Views: 444

Chapter 11 Q 89

This problem is as follows: "the following plot shows how the partial pressures of reactant and products vary with time for the decomposition of compound a into compounds b and c. all three compounds are gases. use this plot to do teh following a- write a balanced chemical equation for the reac...
by Ariana de Souza 4C
Sat Nov 12, 2016 4:49 pm
Forum: Naming
Topic: Iron [ENDORSED]
Replies: 6
Views: 746

Re: Iron [ENDORSED]

yes, it does help! thank you so much
by Ariana de Souza 4C
Fri Nov 11, 2016 7:17 pm
Forum: Naming
Topic: Asterisks on the Table of Ligands [ENDORSED]
Replies: 4
Views: 501

Re: Asterisks on the Table of Ligands [ENDORSED]

Are you sure they aren't polydentates? I haven't been able to find out what kind of dentate they are though
by Ariana de Souza 4C
Fri Nov 11, 2016 4:17 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Chapter 11 Question 43
Replies: 2
Views: 362

Re: Chapter 11 Question 43

Thanks so much! I understand i tnow -- I looked in the notes and we haven't gone through that stuff yet. So I shouldn't expect that in the quiz, right? Some of the practice quizzes have it...
by Ariana de Souza 4C
Thu Nov 10, 2016 8:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Practice Quizzes?? [ENDORSED]
Replies: 1
Views: 385

Practice Quizzes?? [ENDORSED]

Am I going crazy? Because i"m looking at the practice quiz for quiz 3 that we're supposed to turn in and 2 includes material we haven't learned yet and 3 tells us to draw the structure for a coordination complex. Has anyone else run into this problem, or am I just woefully prepared?
by Ariana de Souza 4C
Thu Nov 10, 2016 8:06 pm
Forum: Naming
Topic: Asterisks on the Table of Ligands [ENDORSED]
Replies: 4
Views: 501

Asterisks on the Table of Ligands [ENDORSED]

What do the asterisks next to the last few ligands refer to? Is there specific knowledge about these ligands that we are supposed to know? Thanks
by Ariana de Souza 4C
Thu Nov 10, 2016 8:04 pm
Forum: Naming
Topic: Naming Compounds
Replies: 2
Views: 295

Re: Naming Compounds

One question had ferrate in it. To be specific, question 17.29 a) had "Ferrate" in the answer. Are we supposed to know the latin prefixes for atoms??
by Ariana de Souza 4C
Thu Nov 10, 2016 7:33 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Chapter 11 Question 43
Replies: 2
Views: 362

Chapter 11 Question 43

Chapter 11 Question 43 asks "consider the reaction 2 NO(g) <--> N2 (g) + O2 (g) if the initial partial pressure of NO (g) is 1.0 bar, and x is the equilibriumconcentration of N2, what is the correct equilibrium relation? a) K=(x^2)/(1.0-x) b) K=x^2 c) K=(x^2)/(1.0-2x)^2 d) K=(4x^3)/(1.0-2x)^2 e...
by Ariana de Souza 4C
Wed Nov 09, 2016 6:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to use Kp or Kc
Replies: 2
Views: 497

Re: When to use Kp or Kc

But take, for instance, Chapter 11 Question 13. Part a has a gas in the reactant (The rest are liquids and solids) and the question asks to write the reaction quotient Q. The answer key shows Q in Pressure values. Then comes b, where there are solids, liquids, and aqueous solutions. Then the answer ...
by Ariana de Souza 4C
Mon Nov 07, 2016 6:30 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ch 17 Q 33 d
Replies: 1
Views: 270

Ch 17 Q 33 d

For 17.33 d) why is oxalate bidentate? the structure is two carbon atoms with two oxygen atoms each double bonded onto the carbons. why can a ligand only bond at two places?
by Ariana de Souza 4C
Mon Nov 07, 2016 5:48 pm
Forum: Naming
Topic: Iron [ENDORSED]
Replies: 6
Views: 746

Re: Iron [ENDORSED]

this may be a stupid question, but for example 17.29 a) [Fe(CN)6]4- why is Fe the anion?? As in why is it ferrate?
by Ariana de Souza 4C
Mon Nov 07, 2016 5:37 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Memorizing Ligands?
Replies: 2
Views: 367

Re: Memorizing Ligands?

Yeah, he said today that we're supposed to know them
by Ariana de Souza 4C
Wed Nov 02, 2016 4:07 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Chapter 4 Question 99
Replies: 2
Views: 342

Re: Chapter 4 Question 99

Thanks! that helped a lot
by Ariana de Souza 4C
Sun Oct 30, 2016 2:56 pm
Forum: Hybridization
Topic: Chap 4 Q 75 b
Replies: 2
Views: 316

Re: Chap 4 Q 75 b

Thanks, colin!
by Ariana de Souza 4C
Sat Oct 29, 2016 11:57 am
Forum: Hybridization
Topic: Chap 4 Q 75 b
Replies: 2
Views: 316

Chap 4 Q 75 b

Question 75 asks you to write the hybridization orbitals for CH4O. I know that both carbon and oygen are sp3 because they each have four electron regions around them, but since oxygen has six valence electrons, would the electron config for the hybridized sp3 oxygen orbital look something like this?...
by Ariana de Souza 4C
Fri Oct 28, 2016 7:36 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Chapter 4 Question 99
Replies: 2
Views: 342

Chapter 4 Question 99

Number 99 asks "Just as AlCl3 forms dimers, in the [Bi2Cl4]2- ion two of the chlorine atoms form "bridges" between the two Bi atoms. Propose a structure for the ion." What is this talking about? I tried to go back into the book to look up dimers and bridges, but I didn't understa...
by Ariana de Souza 4C
Fri Oct 28, 2016 4:23 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: M.O.T. on midterm clarification
Replies: 1
Views: 358

M.O.T. on midterm clarification

I know that Professor Lavelle said something about the orbital theory not being on the midterm, but I just wanted to clarify that the midterm will only be up to hybridization? So nothing will be on there regarding antibonding and bonding?
Thanks
by Ariana de Souza 4C
Thu Oct 27, 2016 8:19 pm
Forum: Hybridization
Topic: 5 bonds - sp3d??? [ENDORSED]
Replies: 2
Views: 553

Re: 5 bonds - sp3d??? [ENDORSED]

I think i understand now! I didn't quite get that the orbitals were merging together and becoming one when they hybridize. Thanks so much for the explanation!
by Ariana de Souza 4C
Thu Oct 27, 2016 5:07 pm
Forum: Hybridization
Topic: 5 bonds - sp3d??? [ENDORSED]
Replies: 2
Views: 553

5 bonds - sp3d??? [ENDORSED]

I don't quite understand why 5 bonds on the atom in question means that it has a hybridization of sp3d. I get that the number of electron regions = number of orbitals, but I don't get why. Why can't you just keep filling up the p orbital? Take, for example, BrF3 in problem 4.35 a. Why is it sp3d??? ...
by Ariana de Souza 4C
Mon Oct 24, 2016 6:08 pm
Forum: Lewis Structures
Topic: Lewis structure for O3 (ozone) [ENDORSED]
Replies: 3
Views: 3871

Re: Lewis structure for O3 (ozone) [ENDORSED]

I also had a question on O3
Why is the structure linear, and not like a triangle? Wouldn't it be more stable that way, because then the middle one wouldn't have a charge of +1?
by Ariana de Souza 4C
Mon Oct 24, 2016 6:06 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration for Ions
Replies: 4
Views: 383

Re: Electron Configuration for Ions

I feel like it would be Xe, not Kr -- it just makes more sense that way
by Ariana de Souza 4C
Sun Oct 23, 2016 1:04 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ch 2 Q 43 b
Replies: 1
Views: 224

Ch 2 Q 43 b

I have a question about tungsten (W). Why is its configuration [xe] 4f^14 5d^4 6s^2 and not [xe] 4f^14 5d^ 5 s^1 and take an electron from the s orbital to complete a half d orbital like Chromium???
thanks
by Ariana de Souza 4C
Sat Oct 22, 2016 10:18 pm
Forum: Naming
Topic: Naming for Quiz 2
Replies: 6
Views: 584

Naming for Quiz 2

Will we be expected to be able to know the formula for polyatomic and other species for the second quiz? Or will the formulas be explicitly given to us? Thanks
by Ariana de Souza 4C
Sat Oct 22, 2016 10:13 pm
Forum: Electronegativity
Topic: Chap 2 Q 67
Replies: 2
Views: 357

Re: Chap 2 Q 67

Oh, i never even thought of that! Thanks so much!!
by Ariana de Souza 4C
Sat Oct 22, 2016 2:48 pm
Forum: Electronegativity
Topic: Chap 2 Q 67
Replies: 2
Views: 357

Chap 2 Q 67

This isn't exactly about electronegativity. Question 67 asks "which element of each of the following pairs has the higher electron affinity?" and letter b) asks nitrogen or carbon. Wouldn't it be nitrogen, since it's on the right hand side? Why is it carbon?
Thanks so much :)
by Ariana de Souza 4C
Thu Oct 20, 2016 9:46 pm
Forum: Lewis Structures
Topic: Chap 3 Q 59 [ENDORSED]
Replies: 2
Views: 412

Re: Chap 3 Q 59 [ENDORSED]

Thanks, Andrew! I didn't realize that Chlorine doesn't have the octet rule. Thanks for the help!
by Ariana de Souza 4C
Wed Oct 19, 2016 11:17 pm
Forum: Lewis Structures
Topic: Chap 3 Q 59 [ENDORSED]
Replies: 2
Views: 412

Chap 3 Q 59 [ENDORSED]

Question 59 talks about radicals, and asks you to write the lewis structure of ClO. For ClO, why is Chlorine the one that gets the unpaired electron? Based on the Formal Charge, wouldn't it be better if Oxygen got the unpaired electron?
Thanks!
by Ariana de Souza 4C
Tue Oct 18, 2016 10:04 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Chap 3 Question 11
Replies: 2
Views: 231

Re: Chap 3 Question 11

Oh, I get it now, thanks!
Do all metal ions steal the electrons from the s orbital if the d orbital has not been filled yet?
by Ariana de Souza 4C
Tue Oct 18, 2016 6:06 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Chap 3 Question 11
Replies: 2
Views: 231

Chap 3 Question 11

For question 11 in chapter 3, the question is "Which M3+ ions (where M is a metal) are predicted to have the following ground state electron configurations?"
I don't understand why a) [Ar] 3d^6 is Cobalt 3+ and not Iron 3+. Please help! Thanks :)
by Ariana de Souza 4C
Mon Oct 10, 2016 5:50 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 91
Views: 9149

Re: All students read this sig fig post [ENDORSED]

You have to use both. For example, (2.34+3.45)/1.5 = , use the addition/subtraction rule for (2.34+3.45), which gives you 3 sig fig and use multiplication/division rule for the next step, which gives the final answer with 2 sig fig. I thought that we were supposed to keep as many digits as we could...
by Ariana de Souza 4C
Sat Oct 08, 2016 2:10 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 91
Views: 9149

Re: All students read this sig fig post [ENDORSED]

If a problem requires us to use both multiplication/division and addition/subtraction, which rule do we follow?
by Ariana de Souza 4C
Sat Oct 01, 2016 8:52 pm
Forum: Administrative Questions and Class Announcements
Topic: Is the Periodic Sheet Allowed on Quizzes and Tests?
Replies: 4
Views: 420

Re: Is the Periodic Sheet Allowed on Quizzes and Tests?

We won't get a periodic table? So we have to memorize the masses?
by Ariana de Souza 4C
Wed Sep 28, 2016 9:17 pm
Forum: Student Social/Study Group
Topic: Rieber Hall 14A Study Group (Fall 2016)
Replies: 49
Views: 4277

Re: Rieber Hall 14A Study Group (Fall 2016)

Hey ! I'm in Rieber Vista, and I'd love to be a part of this... only thing is I don't have GroupMe and my phone can't download it. Could we do like a facebook message group thing too? Thanks!
by Ariana de Souza 4C
Tue Sep 27, 2016 5:55 pm
Forum: Balancing Chemical Reactions
Topic: How familiar should we be with Naming compounds? [ENDORSED]
Replies: 8
Views: 1185

Re: How familiar should we be with Naming compounds? [ENDORSED]

Is it necessary to be fluent in nomenclature right now, or are we going to be going over it in lectures and discussion groups in the future?

Go to advanced search