Search found 55 matches

by Melanie Krahn 1C
Tue Dec 15, 2020 7:50 pm
Forum: Trends in The Periodic Table
Topic: Atomic Radius
Replies: 8
Views: 69

Re: Atomic Radius

If the ion has a larger radius, it will also have a less positive charge. If it has a high positive charge then that indicates that the ion has lost some electrons. Electrons play an important part, making up the size of atoms and ions because of the repulsion they cause in the electron cloud.
by Melanie Krahn 1C
Tue Dec 15, 2020 7:47 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: How do you determine the stronger base/acid?
Replies: 7
Views: 65

Re: How do you determine the stronger base/acid?

I think it is helpful to be very familiar with a list of strong acids and bases and then those that are not found on either list can be classified as weak.
by Melanie Krahn 1C
Tue Dec 15, 2020 7:46 pm
Forum: Lewis Structures
Topic: N2H4
Replies: 7
Views: 63

Re: N2H4

Nitrogen does not have an expanded octet because it is in the second period and there is no such thing as a 2d orbital for the second-period elements.
by Melanie Krahn 1C
Tue Dec 15, 2020 7:44 pm
Forum: Lewis Structures
Topic: Tips on drawing Lewis structures
Replies: 20
Views: 157

Re: Tips on drawing Lewis structures

My steps for drawing a Lewis Structure generally look something like this: 1. Finding the number of valence electrons from each atom in the molecule and add them together. 2. Calculate the number of lone pair electrons 3. Determine the number of electrons needed to make the molecule the most stable....
by Melanie Krahn 1C
Tue Dec 15, 2020 7:37 pm
Forum: Bond Lengths & Energies
Topic: Bond length
Replies: 7
Views: 61

Re: Bond length

Is the radius of an atom something we would have to know off of the tp of our heads or is there some way to calculate/gauge that?
by Melanie Krahn 1C
Sun Dec 06, 2020 9:43 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Finding Coordination Number
Replies: 7
Views: 39

Re: Finding Coordination Number

How would I find the coordination number of [Cd(en)BR2]?
by Melanie Krahn 1C
Sun Dec 06, 2020 9:41 pm
Forum: Conjugate Acids & Bases
Topic: Determining Structure of Conjugate Acids and Bases
Replies: 1
Views: 9

Determining Structure of Conjugate Acids and Bases

Hello! How would you solve for a conjugate acid and base? What are the steps to determine the basic structure?
by Melanie Krahn 1C
Sun Dec 06, 2020 9:36 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Tetrahedral vs Square Planar Coordinate Complex
Replies: 8
Views: 87

Re: Tetrahedral vs Square Planar Coordinate Complex

I don't believe we have to differentiate between the two for 14A.
by Melanie Krahn 1C
Sun Dec 06, 2020 9:35 pm
Forum: Bronsted Acids & Bases
Topic: soft salts
Replies: 6
Views: 57

Re: soft salts

I believe that Dr. Lavelle used the phrase 'soft salts" to refer to salts that make water alkaline. I don't think he meant that salts are actually soft but that they produce a soapy, soft feeling when we touch water that is alkaline that feels different from non-Alkakinewater.
by Melanie Krahn 1C
Sun Dec 06, 2020 9:26 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Does pH indicate strength of an acid?
Replies: 26
Views: 169

Re: Does pH indicate strength of an acid?

Yes. pH measures the concentration of hydrogen ions in a solution, strong acids fully dissociate and because of this strong acids generally have a lower pH.
by Melanie Krahn 1C
Sun Nov 29, 2020 9:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Delocalized Bonds
Replies: 5
Views: 46

Delocalized Bonds

Hello! Could someone please help explain to me the importance of delocalized bonds and how we are supposed to visually identify them in a given molecule?
by Melanie Krahn 1C
Sun Nov 29, 2020 9:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar/Nonpolar Bonds vs Molecules
Replies: 4
Views: 39

Polar/Nonpolar Bonds vs Molecules

To my understanding, polar molecules can have nonpolar and polar bonds and nonpolar molecules can have nonpolar and polar bonds. Please correct me if that is wrong. I am struggling to conclude how to determine whether or not a molecule's bonds are able to cancel out another bond and how we can visua...
by Melanie Krahn 1C
Sun Nov 29, 2020 9:34 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance Structures and Molecular Shape
Replies: 3
Views: 19

Resonance Structures and Molecular Shape

How does molecular shape impact resonance structures? Will resonance structures always have the same shape as one another or are there exceptions?
by Melanie Krahn 1C
Sun Nov 29, 2020 9:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma and Pi Bonds
Replies: 5
Views: 54

Sigma and Pi Bonds

Will we be asked to differentiate between sigma and pi bonds when given a molecule with a double or triple bond? Meaning will we have to know exactly what type a particular bond is? If so, how do we go about solving for this?
by Melanie Krahn 1C
Sun Nov 29, 2020 9:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Bond Angles
Replies: 4
Views: 37

Determining Bond Angles

How should we go about determining the bond angles of a molecule, since the VSEPR model only provides qualitative, not quantitative predictions? When given a problem, where would be the first place for us to start?
by Melanie Krahn 1C
Sun Nov 22, 2020 10:06 pm
Forum: Lewis Structures
Topic: Sapling Week 8 #12 [ENDORSED]
Replies: 3
Views: 73

Sapling Week 8 #12 [ENDORSED]

Hello!! I can not solve this problem as many times as I have tried to. Could someone explain to me in as much detail as possible how they approached and then solved the Lewis structure for this problem? I'd appreciate it so much. An organic compound that is distilled from wood has a molar mass of 32...
by Melanie Krahn 1C
Sun Nov 22, 2020 10:03 pm
Forum: Lewis Structures
Topic: Week 8 Sapling Homework #18
Replies: 2
Views: 25

Week 8 Sapling Homework #18

Hello! Could someone explain to me how they drew the structure H2CCCCH2. Most specifically I am thinking I need an explanation of the charges and partial charges because I believe that's where I am going wrong. Thank you!!
by Melanie Krahn 1C
Sun Nov 22, 2020 9:59 pm
Forum: Lewis Structures
Topic: Week 8 Sapling Homework #13
Replies: 3
Views: 21

Week 8 Sapling Homework #13

A 3D representation of cyclohexane ( C6H12 ) molecule, a cyclic compound used in the manufacture of nylon and found in the distillation of petroleum, is shown.

Name the geometry around each carbon atom.

Could someone please explain to me their approach to solving this particular problem?
by Melanie Krahn 1C
Sun Nov 22, 2020 9:57 pm
Forum: Lewis Structures
Topic: Predicting Molecular Shapes
Replies: 3
Views: 26

Predicting Molecular Shapes

When we are asked to predicate a molecular shape based on a given Lewis structure, what is the first thing we should be looking for? Is there a set series of steps to follow?
by Melanie Krahn 1C
Sun Nov 22, 2020 9:50 pm
Forum: Trends in The Periodic Table
Topic: Ion Trends
Replies: 18
Views: 128

Re: Ion Trends

Are there any notable exceptions to the "trends" that we should be able to memorize and know off-hand without relying on looking at the periodic table?
by Melanie Krahn 1C
Sun Nov 15, 2020 7:26 pm
Forum: Bond Lengths & Energies
Topic: Hydrogen Bonds
Replies: 16
Views: 156

Re: Hydrogen Bonds

So to clarify, in conclusion, a hydrogen bond only exist between H and an N, O, or F molecule? H bonds are polar correct? Because the H is attracted to a more electronegative atom?
by Melanie Krahn 1C
Sun Nov 15, 2020 7:22 pm
Forum: Octet Exceptions
Topic: Group 13 elements
Replies: 5
Views: 50

Re: Group 13 elements

Is there anyone thing we should notice immediately to recognize that a molecule may be an exception to the octet rule? And could someone list out a few common molecules that are common exceptions we need to be able to recognize?
by Melanie Krahn 1C
Sun Nov 15, 2020 7:21 pm
Forum: Resonance Structures
Topic: Resonance Structures Clarification
Replies: 8
Views: 49

Re: Resonance Structures Clarification

Could someone clarify how we would be able to recognize which resonance structure contributes most/least to the structure of an ion and/or is the most likely to form?
by Melanie Krahn 1C
Sun Nov 15, 2020 7:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling #20
Replies: 12
Views: 97

Re: Sapling #20

Could someone explain London dispersion forces and when we might be expected to recognize/identify them?
by Melanie Krahn 1C
Sun Nov 15, 2020 7:14 pm
Forum: Ionic & Covalent Bonds
Topic: Resonance Structures
Replies: 5
Views: 44

Resonance Structures

On the Chemical Bonds outline, "Define resonance hybrid and explain its relationship to the individual Lewis structures that contribute," is stated. I know there was a sapling homework question about it but could someone describe what this means exactly and how you would go about determini...
by Melanie Krahn 1C
Sun Nov 08, 2020 11:12 pm
Forum: Lewis Structures
Topic: expanded/smaller octets
Replies: 6
Views: 25

Re: expanded/smaller octets

Can only atoms with d-orbitals have an expanded octet?
by Melanie Krahn 1C
Sun Nov 08, 2020 11:12 pm
Forum: Student Social/Study Group
Topic: midterm
Replies: 6
Views: 65

Re: midterm

I have not heard anything about a midterm review session or any sort of practice session.
by Melanie Krahn 1C
Sun Nov 08, 2020 11:11 pm
Forum: Ionic & Covalent Bonds
Topic: London dispersion forces
Replies: 12
Views: 56

Re: London dispersion forces

When would it be necessary to know what London dispersion forces are and how to recognize them?
by Melanie Krahn 1C
Sun Nov 08, 2020 11:10 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 2 [ENDORSED]
Replies: 11
Views: 138

Re: Midterm 2 [ENDORSED]

The second midterm is not cumulative but the final will be. The midterm will be during your discussion section in week 7.
by Melanie Krahn 1C
Sun Nov 08, 2020 11:08 pm
Forum: Lewis Structures
Topic: Bond Character
Replies: 6
Views: 82

Re: Bond Character

I'm not sure what the question means by ample/overwhelming character either! Does anyone know where it was mentioned in the lecture and/or our textbook?
by Melanie Krahn 1C
Sun Nov 08, 2020 11:06 pm
Forum: Student Social/Study Group
Topic: Mid-quarter Check in
Replies: 67
Views: 294

Re: Mid-quarter Check in

One thing that is hard for me with online school is the fact that collaboration with other students is minimal. I'd love to be able to have study groups and discussions with you all in person and am bummer it's not possible. I'm looking forward to the day when that's something we can do again! The o...
by Melanie Krahn 1C
Sun Nov 08, 2020 11:02 pm
Forum: Lewis Acids & Bases
Topic: Acid vs. Base
Replies: 8
Views: 66

Re: Acid vs. Base

I think it's important to note that we have only learned about Lewis acids and bases so far, we haven't gone over any other acid and base rules/information.
by Melanie Krahn 1C
Sun Nov 01, 2020 7:24 pm
Forum: SI Units, Unit Conversions
Topic: Sapling WEEK 4 #22
Replies: 5
Views: 56

Sapling WEEK 4 #22

Hello! I can't seem to get the right answer to this question. Could someone help explain how they solved? You use an electron microscope in which the matter-wave associated with the electron beam has a wavelength of 0.0431 nm. What is the kinetic energy of an electron in the beam, expressed in elect...
by Melanie Krahn 1C
Sun Nov 01, 2020 7:21 pm
Forum: Student Social/Study Group
Topic: Halloween!!!
Replies: 54
Views: 350

Re: Halloween!!!

I stayed home with my housemates and we watched a scary movie and had a karaoke night!
by Melanie Krahn 1C
Sun Nov 01, 2020 7:19 pm
Forum: Quantum Numbers and The H-Atom
Topic: Nodal Planes
Replies: 10
Views: 72

Re: Nodal Planes

Where are nodal planes found and what are the possible exceptions?
by Melanie Krahn 1C
Sun Nov 01, 2020 7:17 pm
Forum: Properties of Light
Topic: Is c always the speed of light?
Replies: 88
Views: 501

Re: Is c always the speed of light?

C always equals the speed of light, it will never equal another variable when doing the work we do.
by Melanie Krahn 1C
Sun Nov 01, 2020 7:15 pm
Forum: Student Social/Study Group
Topic: Test Scored for Midterm 1
Replies: 49
Views: 384

Re: Test Scored for Midterm 1

I haven't heard any definitive news but I would assume when he releases them he will send out a class email update.
by Melanie Krahn 1C
Sun Nov 01, 2020 7:14 pm
Forum: Properties of Light
Topic: Week 2 Homework Sapling #7
Replies: 5
Views: 68

Week 2 Homework Sapling #7

Hi all. I've been having difficultiess solving this problem. I'd love to see how someone worked it out. Thanks!

How many photons with a wavelength of 769 nm are needed to melt 469 g of ice? The enthalpy of fusion of water can be found in this table.
by Melanie Krahn 1C
Sun Oct 25, 2020 7:39 pm
Forum: General Science Questions
Topic: Webcams
Replies: 17
Views: 132

Re: Webcams

I think depending on your TA a webcam may be preferred but I also learned that using your phone, iPad, or some other computer with a built-in webcam would also be sufficient as long as your workspace is clearly visible.
by Melanie Krahn 1C
Sun Oct 25, 2020 7:37 pm
Forum: Student Social/Study Group
Topic: How to relax
Replies: 126
Views: 726

Re: How to relax

Hey Jalaia!
I've really enjoyed going on walks around campus in the morning to clear my mind before I start work to help me relax before getting productive.
by Melanie Krahn 1C
Sun Oct 25, 2020 7:35 pm
Forum: General Science Questions
Topic: Balancing equations
Replies: 17
Views: 158

Re: Balancing equations

Hello!
I know that there are different approaches to solving a balancing equation problem, however, there is only one correct answer. Dr. Lavelle has suggested starting with the reactant/product that is used the least and then working on from there.
by Melanie Krahn 1C
Sun Oct 25, 2020 7:33 pm
Forum: Administrative Questions and Class Announcements
Topic: midterm 1
Replies: 10
Views: 94

Re: midterm 1

I have heard that the midterm is supposed to be multiple choice with a mixture of both worked and conceptual problems that need to be completed within the fifteen-minute time period. Hope this helps!
by Melanie Krahn 1C
Sun Oct 25, 2020 7:31 pm
Forum: *Black Body Radiation
Topic: What is Black Body?
Replies: 35
Views: 572

Re: What is Black Body?

Hello all,
If I'm not mistaken, Dr. Lavelle specifically mentioned that we do not need to know what black body radiation is and we will not be tested on it.
by Melanie Krahn 1C
Sun Oct 25, 2020 7:29 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: for test 1
Replies: 14
Views: 224

Re: for test 1

Hello! I'm not sure if we'll be asked these questions specifically but I'm sure it would be a good idea to have a conceptual understanding of the definitions as Dr. Lavelle has mentioned he will be putting conceptual questions on this midterm.
by Melanie Krahn 1C
Sat Oct 17, 2020 4:21 pm
Forum: SI Units, Unit Conversions
Topic: Textbook Practice Problem F3
Replies: 2
Views: 21

Textbook Practice Problem F3

F.3 (a) Write the formula for nitric acid. (b) Without doing a calculation, estimate which element in nitric acid occurs with the greatest mass percentage.

How are we supposed to know the formula for nitric acid? Is that something we were already supposed to know or did we go over it at some point?
by Melanie Krahn 1C
Sat Oct 17, 2020 2:23 pm
Forum: SI Units, Unit Conversions
Topic: Textbook Practice Problem E15
Replies: 3
Views: 13

Re: Textbook Practice Problem E15

Also is the 'M' in the problem representative of an element? Is that the mystery metal we're supposed to be solving for?
by Melanie Krahn 1C
Sat Oct 17, 2020 2:21 pm
Forum: SI Units, Unit Conversions
Topic: Textbook Practice Problem E15
Replies: 3
Views: 13

Textbook Practice Problem E15

E.15 The molar mass of the metal hydroxide M ( OH ) 2 is 74.10 g⋅mol −1 . What is the molar mass of the sulfide of this metal? What is the molar mass of the sulfide of this metal? Do we know what the metal is/how do we tell? Can someone please explain what the sulfide of metal is, and how its molar ...
by Melanie Krahn 1C
Sat Oct 17, 2020 1:44 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Textbook Practice Problem F 9
Replies: 1
Views: 119

Textbook Practice Problem F 9

F.9 Vanillin is found in vanilla extracted from Mexican orchids. A report on the analysis of vanillin listed the mass percentage composition as 63.15% C C, 5.30% H H, and 31.55% O O. In what atom ratios are the atoms present in vanillin? The answer I keep getting is slightly different from the solut...
by Melanie Krahn 1C
Sat Oct 17, 2020 1:42 pm
Forum: SI Units, Unit Conversions
Topic: Textbook Practice Problem E 29
Replies: 1
Views: 20

Textbook Practice Problem E 29

I keep getting an answer that is slightly off from the solutions manual? Could somebody walk me through their work, please? Thank you!! E.29 A chemist measured out 8.61 g of copper(II) chloride tetrahydrate, CuCl 2 ⋅ 4 H 2 O . (a) How many moles of CuCl 2 ⋅ 4 H 2 O were measured out? (b) How many mo...
by Melanie Krahn 1C
Sat Oct 17, 2020 1:40 pm
Forum: SI Units, Unit Conversions
Topic: E1 Textbook Practice Problem
Replies: 1
Views: 22

E1 Textbook Practice Problem

When reviewing the solutions to this practice problem I am not sure why 144 pm is multiplied by two and used as 244 pm. Also is the conversion from meters to km at the end necessary? Let me know what you guys think! Thanks for your help. E.1 The field of nanotechnology offers some intriguing possibi...
by Melanie Krahn 1C
Sun Oct 11, 2020 4:48 pm
Forum: Empirical & Molecular Formulas
Topic: Could someone help me solve this?
Replies: 2
Views: 38

Could someone help me solve this?

How many mL of water would you need to add tp 40.0 mL of 0.20 M hydrochloric acid to achieve a 1/5 dilution?
by Melanie Krahn 1C
Sun Oct 11, 2020 4:46 pm
Forum: Limiting Reactant Calculations
Topic: Determining Solution Concentration
Replies: 3
Views: 44

Determining Solution Concentration

Can M = n/v always be used to determine solution concentration? Also, could someone include what the 'n' stands for? Is it a number of moles? Thanks!
by Melanie Krahn 1C
Sun Oct 11, 2020 4:43 pm
Forum: Significant Figures
Topic: Empirical vs Molecular Formula?
Replies: 7
Views: 42

Empirical vs Molecular Formula?

Hi all! I have a few quick questions about empirical and molecular formulas and the difference between the two 1. We can only find the molar mass when the mass of the sample is given to us, correct? 2. Will a question on an exam always specify which formula it intends for us to find and if it doesn'...
by Melanie Krahn 1C
Thu Oct 08, 2020 3:53 pm
Forum: Molarity, Solutions, Dilutions
Topic: Post Assessment Question - Moles
Replies: 3
Views: 30

Post Assessment Question - Moles

Hello! I am confused on how to start this problem out and can’t remember what I’ve learned from lecture that might be helpful. If someone could explain how they reached their answer and the steps to get there, I’d appreciate it. During a summer camping trip, 4 moles of Butane, C4H10, gas were used f...
by Melanie Krahn 1C
Thu Oct 08, 2020 3:47 pm
Forum: Molarity, Solutions, Dilutions
Topic: Post Assessment Survey Question Help
Replies: 3
Views: 44

Post Assessment Survey Question Help

Hello! I am confused on how to start this problem out and can’t remember what I’ve learned from lecture that might be helpful. If someone could explain how they reached their answer and the steps to get there, I’d appreciate it. How many moles of O2 are necessary to burn 2 moles of benzene, C6H6, to...

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