Search found 70 matches
- Tue Mar 12, 2019 4:33 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Test 2 #6 Ordering Reducing/Oxidizing Power
- Replies: 3
- Views: 520
Re: Test 2 #6 Ordering Reducing/Oxidizing Power
For part B. I got that the order of increasing oxidation power was Mg2+ < Ti2+ < Sn2+ because a more positive voltage means a stronger oxidizing agent. I don't know how to solve A and C, though :(
- Tue Mar 12, 2019 4:28 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Inert Electrode
- Replies: 2
- Views: 372
Re: Inert Electrode
Yes, because an inert electrode is needed whenever there is no conducting metal.
- Tue Mar 12, 2019 4:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Yekan Final review slides and solutions 0312
- Replies: 8
- Views: 1215
- Wed Mar 06, 2019 9:36 pm
- Forum: Second Order Reactions
- Topic: multiple choice kinetics
- Replies: 1
- Views: 315
Re: multiple choice kinetics
The answer is (D), and you can find it by process of elimination. (A) we know to be incorrect, and (B) is false because surface area is proportional to chemical reaction speed. (C) is incorrect because reactions between gases are not rapid in ALL cases (e.g. very very low temperature). (E) is incorr...
- Wed Mar 06, 2019 9:33 pm
- Forum: Second Order Reactions
- Topic: multiple choice rate
- Replies: 1
- Views: 327
Re: multiple choice rate
The overall order is 2+1 = 3.
The order with respect to A is 2, and the order with respect to B is 1.
This makes (C) the answer
The order with respect to A is 2, and the order with respect to B is 1.
This makes (C) the answer
- Mon Mar 04, 2019 11:22 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Study Advice
- Replies: 73
- Views: 6809
Re: Study Advice
My favorite way to study is by using The Organic Chemistry Tutor on Youtube! His videos with practice problems somehow always follow Dr. Lavelle's outlines perfectly, and Youtube is perfect for studying in the sense that explanations are clear if you are using a good channel to study and for the pau...
- Mon Mar 04, 2019 10:43 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Order of Reaction
- Replies: 5
- Views: 683
Re: Order of Reaction
Here is a visual that I hope helps:
- Mon Mar 04, 2019 10:39 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: difference between galvanic and voltaic
- Replies: 4
- Views: 2966
Re: difference between galvanic and voltaic
They are the same, but referred to with two different named because they are named after Luigi Galvani and Alessandro Volta.
- Mon Mar 04, 2019 10:29 pm
- Forum: General Rate Laws
- Topic: Units of Rate Constant
- Replies: 4
- Views: 483
Re: Units of Rate Constant
Completing 15.9 in the sixth edition should be very helpful in understanding this concept!
- Thu Feb 28, 2019 5:13 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.91
- Replies: 1
- Views: 281
Re: 14.91
The solution manual states that "a negatively charged electrolyte flows from the cathode to the anode."
- Thu Feb 28, 2019 5:08 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: cathode vs anode
- Replies: 4
- Views: 528
Re: cathode vs anode
You can determine the cathode reaction and anode reaction by seeing which combination would cause you to end up with a greater voltage when the two reactions are combined
- Thu Feb 28, 2019 4:59 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Pt inert electrode
- Replies: 9
- Views: 1785
Re: Pt inert electrode
Melody P 2B wrote:Would you add Pt(s) to both sides?
You would add Pt(s) to whichever side lacks solid metal.
- Thu Feb 21, 2019 2:41 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard Cell Potential
- Replies: 2
- Views: 379
Re: Standard Cell Potential
Standard corresponds with 1 mole/L, 1 atm, and 25 degrees C
- Thu Feb 21, 2019 2:30 pm
- Forum: Balancing Redox Reactions
- Topic: Homework 14.5 part d
- Replies: 4
- Views: 427
Re: Homework 14.5 part d
The Solution Manual Errors PDF on Professor Lavelle's website doesn't point to any errors in the solution manual for problem 14.5, so I would assume that the given answer is right
- Thu Feb 21, 2019 2:22 pm
- Forum: Balancing Redox Reactions
- Topic: balance equations
- Replies: 2
- Views: 407
- Sun Feb 17, 2019 10:18 pm
- Forum: Student Social/Study Group
- Topic: Serenade
- Replies: 2
- Views: 450
Re: Serenade
HAHA thanks, I wish the 1 pm class got serenaded :(
- Sun Feb 17, 2019 10:14 pm
- Forum: Student Social/Study Group
- Topic: absent 2/15
- Replies: 3
- Views: 395
Re: absent 2/15
More specifically, we discussed the three different ways to find free energy:
1. Using standard enthalpy of formation and standard molar entropy
2. Hess-style approach of adding/subtracting delta G (rxn 1) and delta G (rxn 2)
3. Using G(products) - G(reactants)
1. Using standard enthalpy of formation and standard molar entropy
2. Hess-style approach of adding/subtracting delta G (rxn 1) and delta G (rxn 2)
3. Using G(products) - G(reactants)
- Sun Feb 17, 2019 10:10 pm
- Forum: Student Social/Study Group
- Topic: Chemistry News
- Replies: 135
- Views: 164706
Re: Chemistry News
Interesting stuff for those interested in art history :)
https://phys.org/news/2019-02-art-acne-georgia-okeeffe.html
https://phys.org/news/2019-02-art-acne-georgia-okeeffe.html
- Sun Feb 10, 2019 12:00 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work Done
- Replies: 2
- Views: 314
Re: Work Done
If energy leaves a system, the system does work on its surroundings. If energy enters a system, work is done on the system.
- Sun Feb 03, 2019 2:34 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Review
- Replies: 14
- Views: 1200
Re: Midterm Review
Dr. Lavelle also usually does midterm review during class in the days leading up to the midterm!
- Sun Feb 03, 2019 2:33 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calibrating the Calorimeter
- Replies: 1
- Views: 618
Re: Calibrating the Calorimeter
From http://www.dynamicscience.com.au/tester/solutions1/chemistry/energy/calorimeter.htm : "Calibration of the calorimeter is the determination of how many joules of energy are required to raise the temperature of the contents by one degree Celsius. This is known as the calibration factor of th...
- Thu Jan 31, 2019 8:40 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 2
- Views: 250
Re: Bond Enthalpies
You would look at the total of all of the bonds: the three C=C bonds and three C-C bonds, for instance.
- Thu Jan 31, 2019 8:38 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed System
- Replies: 6
- Views: 643
Re: Closed System
Closed systems cannot exchange matter with their surroundings, but can exchange energy.
If a sealed beaker is heated, for instance, nothing physically can leave or enter the beaker. However, there will be a heat energy transfer.
If a sealed beaker is heated, for instance, nothing physically can leave or enter the beaker. However, there will be a heat energy transfer.
- Thu Jan 31, 2019 8:36 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Open, closed, or isolated systems
- Replies: 10
- Views: 39054
Re: Open, closed, or isolated systems
Here is a visual I hope will help!
- Thu Jan 31, 2019 8:34 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work
- Replies: 3
- Views: 530
Re: Work
If energy leaves a system, the system does work on its surroundings. If energy enters a system, work is done on the system.
- Sat Jan 26, 2019 3:55 pm
- Forum: Phase Changes & Related Calculations
- Topic: Modules
- Replies: 17
- Views: 1291
Re: Modules
Do the modules tell you your score at the end? Or are they just for practice?
- Thu Jan 24, 2019 4:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Tricks for identifying Strong/Weak Acids & Bases
- Replies: 6
- Views: 567
Tricks for identifying Strong/Weak Acids & Bases
Does anyone know of any tips or tricks that will allow you immediately to identify an acid or base as weak or strong?
- Tue Jan 22, 2019 2:18 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ignoring x
- Replies: 10
- Views: 862
Re: ignoring x
Do we need to write anything to indicate or explain why we have ignored x? Or can we just do it without indication if our problem passes the 5% test?
- Tue Jan 22, 2019 2:13 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Endothermic vs. Exothermic
- Replies: 8
- Views: 790
Re: Endothermic vs. Exothermic
here is a visual representation:
- Thu Jan 17, 2019 10:55 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: conjugates
- Replies: 3
- Views: 220
Re: conjugates
This is not necessarily true. For instance, a weak acid/base will have a stronger conjugate base/acid.
- Thu Jan 17, 2019 10:45 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q<K
- Replies: 4
- Views: 1277
Re: Q<K
Yes! Here is a visual representation of that:
- Sat Jan 12, 2019 2:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculating K
- Replies: 4
- Views: 186
Re: Calculating K
You would use equilibrium concentrations
- Sat Jan 12, 2019 2:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.45 6th Edition
- Replies: 1
- Views: 200
Re: 11.45 6th Edition
You can compare the equilibrium constants for the dissociation of CL 2 versus the dissociation of F 2 to determine stability. Because the dissociation of F 2 has a larger equilibrium constant than that of CL 2 and a large equilibrium constant means that the equilibrium concentration of the products ...
- Fri Jan 11, 2019 2:30 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Volume increasing
- Replies: 4
- Views: 253
Re: Volume increasing
Yes, I believe it does!
- Thu Dec 06, 2018 3:32 pm
- Forum: General Science Questions
- Topic: Chemistry Community [ENDORSED]
- Replies: 7
- Views: 839
Re: Chemistry Community [ENDORSED]
Claire Guo 1B wrote:TA's wont be checking if we did three posts every week right? Because I think I have the 30 posts we need but some weeks I forgot and then caught up later.
I think that should be fine!
- Tue Dec 04, 2018 7:28 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH scale
- Replies: 2
- Views: 246
Re: pH scale
This part is a little confusing for me. If, basic solutions have less H3O+ than acids, and the pH log measures the amount of H3O+, then why do the larger numbers (8-14) correspond to bases? pH = -log 10 With this knowledge, the pH of a number like 10 -1 (pH = 1) would be lower than the pH of a numb...
- Tue Dec 04, 2018 7:21 pm
- Forum: Naming
- Topic: Textbook Question 9C.1
- Replies: 2
- Views: 243
Re: Textbook Question 9C.1
a) says [Fe(CN)6]^4- however the answer is tetracholoroferrate (II) why is iron called ferrate and why is the charge (II) and not (IV) Each CN contributes to a -1 charge, meaning (CN) 6 has a total charge of -6. If [Fe(CN)6]^4- has a net charge of -4 and (CN)6 contributes to -6 of that charge, Fe m...
- Tue Dec 04, 2018 7:17 pm
- Forum: General Science Questions
- Topic: Chemistry Community [ENDORSED]
- Replies: 7
- Views: 839
Re: Chemistry Community [ENDORSED]
Will our TAs give us points for chem community just by looking up our names and seeing how many posts we have?
- Tue Dec 04, 2018 5:37 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Naming Acids
- Replies: 1
- Views: 1518
Re: Naming Acids
From https://courses.lumenlearning.com/introchem/chapter/naming-acids-and-bases/ - Acids are named based on their anion — the ion attached to the hydrogen. In simple binary acids, one ion is attached to hydrogen. Names for such acids consist of the prefix “hydro-“, the first syllable of the anion, a...
- Fri Nov 30, 2018 4:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Pentagonal bipyramidal
- Replies: 4
- Views: 1307
Re: Pentagonal bipyramidal
IF7 is an example of a molecule with this shape!
- Fri Nov 30, 2018 4:13 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Sigma and Pi Bonds
- Replies: 12
- Views: 1033
Re: Sigma and Pi Bonds
Here's a visual that I hope helps!
- Fri Nov 30, 2018 4:00 pm
- Forum: Dipole Moments
- Topic: Molecular Geometry and polarity
- Replies: 5
- Views: 422
Re: Molecular Geometry and polarity
Adrian C 1D wrote:If a molecule's molecular geometry is linear, is it a good indicator of the molecule being nonpolar?
Not necessarily, e.g. HCN is linear, but polar
- Fri Nov 30, 2018 3:56 pm
- Forum: Hybridization
- Topic: 2s or s?
- Replies: 7
- Views: 647
Re: 2s or s?
Andrew Sun 1I wrote:if a question asks what is the hybridization around the central atom, does it need a coefficient to specify which energy level?
My TA said that we don't need to specify which energy level
- Thu Nov 29, 2018 12:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Wednesday Lecture Notes
- Replies: 3
- Views: 381
Re: Wednesday Lecture Notes
Thank you so much!!
- Thu Nov 22, 2018 3:18 pm
- Forum: Hybridization
- Topic: Sixth Edition, Example 4.6
- Replies: 2
- Views: 284
Re: Sixth Edition, Example 4.6
I think I remember my TA saying that the numbers denoting row are unnecessary (though correct) when writing hybridizations. So in your case, writing them either way would probably be alright!
- Thu Nov 22, 2018 3:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: I3- ion shape
- Replies: 2
- Views: 168
Re: I3- ion shape
I3- ions have three lone pairs around the central I atom, meaning the molecule as a whole has an electron geometry of trigonal bipyramidal and a linear molecular geometry.
- Mon Nov 19, 2018 8:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Length and Bond Angles
- Replies: 2
- Views: 196
Re: Bond Length and Bond Angles
As far as our class is concerned, bond lengths affect bond angles to such a small extent that this effect can be ignored.
- Sun Nov 18, 2018 9:54 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework Week 8 [ENDORSED]
- Replies: 7
- Views: 2147
Re: Homework Week 8 [ENDORSED]
cara_cavarretta_3F wrote:Even though we still have discussion for Mon-Wed is our homework still due the next week as well? Sorry, just to be sure.
For my discussion, we could either turn in 7 homework problems this week or both sets (14 problems) the following week
- Sun Nov 18, 2018 9:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles Between the Same shape
- Replies: 6
- Views: 658
Re: Bond Angles Between the Same shape
I think bond angles are the same for molecules of the same shape (at least the ones we've learned about so far)
- Thu Nov 15, 2018 4:09 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: HW Q 4.13
- Replies: 2
- Views: 292
Re: HW Q 4.13
Is this helpful in visualizing the molecular geometry?
- Thu Nov 15, 2018 3:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: HW Q 4.11
- Replies: 4
- Views: 4308
Re: HW Q 4.11
SCl4 has a seesaw molecular geometry because you must take into account the effect that the lone pair on S has on shape; if there was no lone pair on SCl4, the shape would be tetrahedral. If there was no lone pair it would just be SCl4. Would it not be square planar? To be square planar, a molecule...
- Thu Nov 15, 2018 3:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: HW Q 4.11
- Replies: 4
- Views: 4308
Re: HW Q 4.11
SCl4 has a seesaw molecular geometry because you must take into account the effect that the lone pair on S has on shape; if there was no lone pair on SCl4, the shape would be tetrahedral.
- Fri Nov 09, 2018 6:21 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability Vs. Polarizing Power
- Replies: 3
- Views: 671
Re: Polarizability Vs. Polarizing Power
From http://wwwchem.uwimona.edu.jm/courses/CHEM1902/IC10K_MG_Fajans.html : "The ability of a cation to distort an anion is known as its polarization power and the tendency of the anion to become polarized by the cation is known as its polarizability."
- Fri Nov 09, 2018 6:15 pm
- Forum: Balancing Chemical Reactions
- Topic: Combustion Equation
- Replies: 21
- Views: 2742
Re: Combustion Equation
Combustion reactions always have oxygen and a hydrocarbon as reactants and will always produce CO2 and H2O.
- Fri Nov 09, 2018 6:13 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 8
- Views: 709
Re: Electronegativity
If an element is more electronegative than another atom, it will attract electrons more strongly.
- Thu Nov 01, 2018 5:56 pm
- Forum: Student Social/Study Group
- Topic: Studying
- Replies: 7
- Views: 746
Re: Studying
I usually study by looking up "[topic] practice problems" on youtube and following along. The Organic Chemistry Tutor's videos have been really helpful for me!
- Thu Nov 01, 2018 5:27 pm
- Forum: Lewis Structures
- Topic: Lewis Structures- formal charge
- Replies: 4
- Views: 480
Re: Lewis Structures- formal charge
Javier_Ochoa_DIS_3J wrote:This is the equation to find the formal charge.
Valance electrons - (lone pair electrons + number of bonds) = Formal charge.
I like using this equation more than the FC = V - (L + S/2) one because there is less room for error!
- Thu Nov 01, 2018 5:20 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radius
- Replies: 3
- Views: 221
Re: Atomic Radius
To convert from meters to picometers, you multiply the length value by 1e+12
- Fri Oct 26, 2018 5:55 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Tricks to remembering orbitals
- Replies: 2
- Views: 694
Re: Tricks to remembering orbitals
This diagram is super helpful for me!
- Fri Oct 26, 2018 5:46 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Test #2
- Replies: 3
- Views: 404
Re: Test #2
Orbitals that have the same energy levels are called degenerate (same n and l quantum numbers)
- Thu Oct 18, 2018 3:40 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectroscopy vs Molecular Spectroscopy
- Replies: 2
- Views: 371
Re: Atomic Spectroscopy vs Molecular Spectroscopy
I'm not really sure myself, but here is a link that might help:
https://www.quora.com/How-do-molecular-and-atomic-spectroscopy-differ
https://www.quora.com/How-do-molecular-and-atomic-spectroscopy-differ
- Thu Oct 18, 2018 3:13 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Class Grading
- Replies: 9
- Views: 1117
Re: Class Grading
I think our grades will be based off of the class average out of 500 points
- Thu Oct 18, 2018 3:10 pm
- Forum: Trends in The Periodic Table
- Topic: Period Table 'blocks'
- Replies: 5
- Views: 479
Re: Period Table 'blocks'
For example, Potassium can be written as 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 or [Ar] 4s^1; it is part of the S block
- Sun Oct 14, 2018 12:48 pm
- Forum: Photoelectric Effect
- Topic: Threshold Energy and Energy Levels
- Replies: 1
- Views: 136
Re: Threshold Energy and Energy Levels
Yes, each metal has a unique threshold energy
- Wed Oct 10, 2018 4:39 pm
- Forum: Limiting Reactant Calculations
- Topic: Test 1
- Replies: 3
- Views: 423
Re: Test 1
I worked without stopping the entire way through and was probably able to finish with 5 minutes left to check my work.
- Wed Oct 10, 2018 4:37 pm
- Forum: Properties of Light
- Topic: Homework Question 1A15
- Replies: 3
- Views: 230
Re: Homework Question 1A15
The first step is knowing that this transition is in the Lyman series, but I'm also not sure where to go after this.
- Wed Oct 10, 2018 4:28 pm
- Forum: SI Units, Unit Conversions
- Topic: Quiz 1- Addition to what we should know?
- Replies: 5
- Views: 588
Re: Quiz 1- Addition to what we should know?
Hannah Padilla 1H wrote:For the first test, will we need to be able to identify molecular formulas from their written name? For example in problem F3.) “Write the formula for nitric acid”
Molecular formulas will be given!
- Tue Oct 09, 2018 7:24 pm
- Forum: Significant Figures
- Topic: 200. decimal sig figs
- Replies: 5
- Views: 5364
Re: 200. decimal sig figs
200.0 offers more precision than 200., so it follows that 200.0 has one more significant figure than 200.
- Tue Oct 09, 2018 7:06 pm
- Forum: Photoelectric Effect
- Topic: post assessment
- Replies: 2
- Views: 221
Re: post assessment
I agree that the answer should be C; light with a frequency higher than the threshold energy should be able to remove electrons
- Tue Oct 09, 2018 7:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Advice from a Medical Student [ENDORSED]
- Replies: 297
- Views: 385148
Re: Advice from a Medical Student [ENDORSED]
Thank you for this advice; I switched into this class and was having doubts about which chemistry series would be best for me to take part in, and this makes me feel much more confident!