Search found 26 matches

by Alexandra_Ivanova_1A
Sun Mar 19, 2017 1:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Exam Details and Review Sessions Winter 2017
Replies: 114
Views: 13236

Re: Final Exam Details and Review Sessions Winter 2017

Minu Reddy wrote:Hi Everyone,
I was wondering if we need to know how to draw a boat conformation?

Thank you


Not sure about what the other replier said, but Professor Lavelle said we only need to know how to draw a chair conformation on the test. You should be able to identify the other conformations though.
by Alexandra_Ivanova_1A
Mon Mar 13, 2017 12:09 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 883035

Re: Post All Chemistry Jokes Here

I'd post more chemistry jokes on here, but I feel like the sheer amount of content on here might Barium.
by Alexandra_Ivanova_1A
Wed Feb 15, 2017 1:59 pm
Forum: Balancing Redox Reactions
Topic: Balancing (Acidic vs. Basic Balancing)
Replies: 3
Views: 408

Balancing (Acidic vs. Basic Balancing)

Are we expected to know how to balance reactions in both acidic and basic solutions? Will it be specified in the problem which it is? What if the reaction is occuring in water?
by Alexandra_Ivanova_1A
Sun Feb 12, 2017 8:32 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: When to use reversible work equation?
Replies: 1
Views: 209

When to use reversible work equation?

Do we only use the reversible work equation when it is explicitly stated the reaction is reversible? When do we know a reaction is reversible? Is isothermal synonymous with reversible (i.e, do we use the reversible work equation when isothermal is stated in the question?)
by Alexandra_Ivanova_1A
Sun Feb 05, 2017 7:46 pm
Forum: Phase Changes & Related Calculations
Topic: Balancing Equations/When To Use Integers and When Not To?
Replies: 3
Views: 302

Balancing Equations/When To Use Integers and When Not To?

I've noticed in the textbook/course reader when balancing equations to calculate things like enthalpy and entropy sometimes we balance the equations with integers, and other times we will have values that are fractions. When do we know when it is necessary to use integers and when not to, since this...
by Alexandra_Ivanova_1A
Sat Jan 28, 2017 12:00 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.53 / W=0 for Bomb Calorimeters ??
Replies: 1
Views: 220

8.53 / W=0 for Bomb Calorimeters ??

In the Solutions Manual, it says that since a bomb calorimeter is used, the volume is fixed, and therefore w=0. Is this the case for all closed systems?
by Alexandra_Ivanova_1A
Sat Jan 21, 2017 3:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Reaction Enthalpies HW Q49
Replies: 1
Views: 237

Re: Reaction Enthalpies HW Q49

Since no pressure or volume is indicated, we use PV=nRT to find PV and then find the change in internal energy for the rxn by using the equation:
(delta U)=(delta H)-(PV). Since the reaction is at standard conditions, I think we assume the pressure is constant.
by Alexandra_Ivanova_1A
Fri Jan 13, 2017 10:01 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy Question
Replies: 4
Views: 324

Standard Enthalpy Question

I understand that the standard enthalpy of formation an element in its standard state is zero, however I'm confused as to the reactions used to signify them: O 2 --> O 2 Br 2 --> Br 2 ...etc. What exactly do these reactions mean? What is the purpose of a reaction where the products and reactants are...
by Alexandra_Ivanova_1A
Fri Dec 02, 2016 3:35 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Homework Question 13.1
Replies: 2
Views: 2441

Re: Homework Question 13.1

1. The solid sodium acetate will dissociate into separate sodium and separate acetate, so you will be adding additional acetate to the solution and the concentration of H3O+ will in turn decrease. 2. Percentage deprotonation is the conjugate base over its acid. Keeping that in mind. when adding hydr...
by Alexandra_Ivanova_1A
Fri Nov 25, 2016 6:22 pm
Forum: Calculating the pH of Salt Solutions
Topic: Salts as Acids and Bases
Replies: 1
Views: 245

Re: Salts as Acids and Bases

I think it has more to do with what is actually reacting. In the example you are using, we are looking at NH 4 Cl. This is a salt that contains an acid within it (NH 4 ). The acid is what is reacting with water, not the anion (Cl - ). Since Cl - isn't reacting, it doesn't affect the pH. This is furt...
by Alexandra_Ivanova_1A
Fri Nov 18, 2016 10:08 am
Forum: Amphoteric Compounds
Topic: With respect to other compounds....
Replies: 1
Views: 373

Re: With respect to other compounds....

I know that hydroxides of the metals of Group 3 (and higher) generally tend to have amphoteric properties and are slightly basic, so I suppose it depends on the compound itself. "In general, these compounds tend to be more basic than acidic; thus, the oxides and hydroxides of aluminum, iron, an...
by Alexandra_Ivanova_1A
Fri Nov 11, 2016 8:05 am
Forum: Naming
Topic: Asterisks on the Table of Ligands [ENDORSED]
Replies: 4
Views: 495

Re: Asterisks on the Table of Ligands [ENDORSED]

You're referring to the table on page 117 of the course reader, yes? If so, the asterisk means that the ligand is polydentate (chelate).
by Alexandra_Ivanova_1A
Fri Nov 04, 2016 12:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Trans- vs Cis- Complexes
Replies: 1
Views: 250

Trans- vs Cis- Complexes

On page 116 of the Course Reader, the notes cover cis-diamminedichloroplatinum(II) as well as trans-diamminedichloriplatinum(II). Aside from what they are able to/are more likely bond to, what are the differences in the properties of a cis and trans version of a molecule, and how would each form? Is...
by Alexandra_Ivanova_1A
Fri Oct 28, 2016 7:56 am
Forum: Hybridization
Topic: VESPR
Replies: 2
Views: 340

Re: VESPR

A trigonal pyramidal shape occurs when an atom has four areas of electron density-- a lone pair of electrons, and three bonds. In the case of ClO2+, it does have four regions of electron density, but it has two lone pairs and two bonds, so it follows a bent structure instead.
by Alexandra_Ivanova_1A
Sat Oct 22, 2016 6:24 pm
Forum: Sigma & Pi Bonds
Topic: Valence Electron Configuration
Replies: 1
Views: 248

Valence Electron Configuration

Where can I find out how to do the valence electron configuration notation needed for problems like 6 and 7 in the Quiz 2 Preparation, Fall 2014 problem set? Will it be covered in the upcoming quiz if it hasn't been explicitly discussed in class?
by Alexandra_Ivanova_1A
Fri Oct 21, 2016 7:56 am
Forum: Formal Charge and Oxidation Numbers
Topic: Problem 3.65
Replies: 1
Views: 231

Re: Problem 3.65

You're right-- Nobel gases (Group 18 elements) contain a full octet, so they don't usually (or at least, do not easily) form bonds with other elements. That being said, it is possible for them to bond, though that bond is often very weak. Typically, elements n=3 and above don't follow the octet rule...
by Alexandra_Ivanova_1A
Fri Oct 21, 2016 7:47 am
Forum: Hybridization
Topic: Electron Configuration video
Replies: 1
Views: 367

Re: Electron Configuration video

Thank you so much, that video was really helpful. I find that this Khan Academy series is helpful too: https://www.khanacademy.org/science/chemistry/electronic-structure-of-atoms/electron-configurations-jay-sal/v/orbitals
by Alexandra_Ivanova_1A
Fri Oct 14, 2016 12:11 pm
Forum: Ionic & Covalent Bonds
Topic: question 2.93
Replies: 3
Views: 449

Re: question 2.93

I believe there is an error in the solutions manual. On Lavelle's website, the "Solutions Manual Errors" state: 2.93 In the picture, it shows A (smaller atom) + B (larger atom) --> C (larger ion) + D (smaller ion) The solution manual says that A=Na and B=Cl, and it references Figure 2.20 w...
by Alexandra_Ivanova_1A
Fri Oct 14, 2016 12:06 pm
Forum: Properties of Light
Topic: Emit Light
Replies: 3
Views: 439

Re: Emit Light

Yes, a negative energy means that light is being emitted, while a positive one means light is being absorbed.
by Alexandra_Ivanova_1A
Fri Oct 07, 2016 10:00 am
Forum: Administrative Questions and Class Announcements
Topic: Rounding and Accuracy During Tests
Replies: 4
Views: 527

Re: Rounding and Accuracy During Tests

From looking at the solutions in the textbook solutions manual and workbook, it constantly wants us to round off to the proper number of sig figs at each step of the problem. If you do that, it's easier to keep track of sig figs from the beginning because you just end up with the smallest number of...
by Alexandra_Ivanova_1A
Thu Oct 06, 2016 8:18 pm
Forum: Photoelectric Effect
Topic: Question 1.33 (c) from the textbook [ENDORSED]
Replies: 2
Views: 469

Re: Question 1.33 (c) from the textbook [ENDORSED]

For 1.33C you use the equation E potential = E threshold + E kinetic . In part B, you find the threshold energy using the given frequency (2.50 x 10 16 Hz) and the equation E = hv. Page 43 of the Course Reader goes over this a bit, but essentially, the equation for kinetic energy is (0.5)*(mass of e...
by Alexandra_Ivanova_1A
Thu Oct 06, 2016 8:02 pm
Forum: Administrative Questions and Class Announcements
Topic: Rounding and Accuracy During Tests
Replies: 4
Views: 527

Rounding and Accuracy During Tests

How much wiggle room do we have in terms of rounding accuracy during the tests, quizzes, etc? I know that general rounding and significant figure rules stated in the beginning of the Course Reader apply, but it seems like using certain constants or rounding off constants can give a bit of a differen...
by Alexandra_Ivanova_1A
Tue Sep 27, 2016 9:32 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Audio-Visual Topic Question
Replies: 2
Views: 334

Re: Limiting Reactant Audio-Visual Topic Question

You're right, the mass of the products can't be more than the mass of the reactants due to The Law of Conservation of Mass (matter cannot be created or destroyed). Based on this, the mass of the products actually equals the mass of the reactants, as no change in mass occurs through a reaction. Produ...
by Alexandra_Ivanova_1A
Tue Sep 27, 2016 9:16 pm
Forum: Molarity, Solutions, Dilutions
Topic: G #17 b
Replies: 2
Views: 808

Re: G #17 b

CuSO4 • 5H2O is a hydrate, yes. We include the water through both accounting for its contribution to the total molar mass of CuSO4 • 5H2O, as well as through the final volume. This is a dilution problem, so it is helpful to think of these sorts of problems (dilutions with hydrates) through how they ...
by Alexandra_Ivanova_1A
Tue Sep 27, 2016 9:01 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 113
Views: 55347

Re: Rusty on High School Chem [ENDORSED]

Just to add on-- Crash Course on Youtube is great for conceptual chemistry and overarching themes, and really helps with understanding the "greater picture" when it comes to some concepts. If you are looking for more step-by-step instruction with worked out examples, I'd highly recommend u...

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