Search found 97 matches

by Samantha Low 3D
Sun Feb 21, 2021 6:47 pm
Forum: Calculating Work of Expansion
Topic: adiabatic processes
Replies: 18
Views: 32

Re: adiabatic processes

An adiabatic process means that no energy is transferred as heat, meaning that q=0. This does not mean that w=0. In an abiotic process, w can =0, but it can also be another value. Textbook problem 4B.9 illustrates this idea well. Hope this helps!
by Samantha Low 3D
Sun Feb 21, 2021 6:42 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Textbook Problem 4I.7
Replies: 1
Views: 9

Textbook Problem 4I.7

For Textbook Problem 4I.7, ΔS surr = -ΔH sys /T and ΔS sys =ΔH sys /T. Since this is true, then ΔS sys =-ΔS surr . Since ΔS sys =-ΔS surr , then ΔS univ =0. Does this mean at its boiling point, melting point, and freezing point the system is at equilibrium? And do these equations hold true when the ...
by Samantha Low 3D
Sun Feb 21, 2021 6:20 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Textbook 4.17e
Replies: 4
Views: 8

Re: Textbook 4.17e

I think they include sf because -3.0 kJ has 2 sigfigs, but when we convert to J, -3000J only has 1 sigfig. The sf shows that the original calculation was following the sigfig rules, and that's how we get -3000J (despite only having 1 sigfig). Hope this helps!
by Samantha Low 3D
Sun Feb 21, 2021 6:16 pm
Forum: Student Social/Study Group
Topic: Fav Shows of the Moment
Replies: 98
Views: 219

Re: Fav Shows of the Moment

I just binged leverage! Definitely a good show that doesn't require too much attention to enjoy!
by Samantha Low 3D
Sun Feb 21, 2021 6:14 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4.15 Solutions Manual Clarification
Replies: 1
Views: 11

4.15 Solutions Manual Clarification

For Textbook problem 4.15, the Solutions Manual uses -4.18 J*g -1 *°C -1 to plug into q=mc(T f -T i ) to find T f . Why do they use -4.18 instead of of +4.18 that we usually use? Here's the problem for reference: Hydrochloric acid oxidizes zinc metal in a reaction that produces hydrogen gas and chlo...
by Samantha Low 3D
Sun Feb 14, 2021 4:10 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: q(rev)/T and ΔS(sys) and ΔS(surr)
Replies: 1
Views: 13

q(rev)/T and ΔS(sys) and ΔS(surr)

If ΔS (surr) = q(rev)/T and ΔS (surr)=-ΔH(sys)/T and temperature is constant, we can say that q(rev)=-ΔH(sys).

I'm confused how ΔS(sys)= q(rev)/T but ΔS(sys) is not equal to ΔS (surr). May someone please clarify how this works out conceptually and mathematically? Thank you!
by Samantha Low 3D
Sun Feb 14, 2021 3:53 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Week 5/6 Sapling #7 Conceptually
Replies: 1
Views: 13

Week 5/6 Sapling #7 Conceptually

Why does calculating the Juoles (calculated from Watts*time) divided by moles of substance evaporated give us ΔH vap ? May someone please clarify conceptually what ΔH vap is? I thought it was the energy needed to vaporize a substance, but I don't get how the moles of vaporized substance plays into t...
by Samantha Low 3D
Sun Feb 14, 2021 3:40 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard Entropy of Vaporization
Replies: 1
Views: 16

Standard Entropy of Vaporization

For Sapling Week 5/6 #8, we were asked to determine the standard molar entropy of vaporization of water at 31.0 degrees Celsius. May someone please explain what this means in simple terms? Also, the "hint" sapling gave us was to break it down into 3 steps: 1. heating water from 31.0 degree...
by Samantha Low 3D
Sun Feb 14, 2021 3:27 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: What molecular structures are unlikely to have residual entropy?
Replies: 1
Views: 14

What molecular structures are unlikely to have residual entropy?

For Week 5/6 Sapling #1, we were asked to determine which structures were likely to have residual entropy. The solution writes: "The molecules CO2 and Cl2 are symmetrical. Since switching the orientation of a symmetrical molecule does not result in increased disorder, it is unlikely that CO2 an...
by Samantha Low 3D
Sun Feb 14, 2021 3:11 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Equations
Replies: 2
Views: 11

Re: Entropy Equations

Adding on, we us ΔS = nRln(V2/V1) when we're working with an isothermal reversible expansion, where volume and pressure change and temperature is constant. We us ΔS = nCln(T2/T1) when we have constant pressure and changing temperature (use C p ) or constant volume and changing temperature (C v ). Ho...
by Samantha Low 3D
Sun Feb 07, 2021 8:47 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sapling #20
Replies: 9
Views: 29

Re: Sapling #20

Since the volume does not change, deltaV=0.
Since w=-P(deltaV), w= P*0=0.
delta u (internal energy) = q+w, so since w=0, delta u=q.
Hope this helps!
by Samantha Low 3D
Sun Feb 07, 2021 8:35 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Week 3/4 Sapling #19: Do we need mass?
Replies: 1
Views: 35

Week 3/4 Sapling #19: Do we need mass?

The solution to Sapling #19 doesn't use the mass in its calculation. Is this because the mass of the solution used to calibrate the calorimeter is the same as the mass of the solution in the experiment and they cancel out? Or is it because mass isn't included in the specific heat calculation? In oth...
by Samantha Low 3D
Sun Feb 07, 2021 8:17 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sapling #18 Cv and Cp
Replies: 4
Views: 30

Re: Sapling #18 Cv and Cp

The constant‑pressure molar specific heat is CP. In my problem, that was given to me as CP=7R/2 The change in internal energy ΔUthat corresponds to a temperature change ΔT is given by ΔU=nRCVT where CV is the constant‑volume molar specific heat of the gas. CV is related to CP by CV=CP-R. In my case,...
by Samantha Low 3D
Sun Feb 07, 2021 8:10 pm
Forum: Student Social/Study Group
Topic: Culinary Chemistry
Replies: 62
Views: 345

Re: Culinary Chemistry

My family has an ongoing debate if adding salt to pasta water makes the water boil faster or slower. The argument for faster is that adding salt disrupts the surface tension of the water, and contributes to it boiling faster. The argument for slower is that salt raises the boiling point of the water...
by Samantha Low 3D
Sun Feb 07, 2021 8:02 pm
Forum: Calculating Work of Expansion
Topic: Sapling #14: Why do we use two different values of R for Path A?
Replies: 5
Views: 28

Sapling #14: Why do we use two different values of R for Path A?

Hi! With the help of Chemistry Community, I was able to solve this problem. However, I'm still confused on why we use two different R values (0.08206 atm*L/(K*mol) and 8.13 J/(K*mol)). How do we know when to use each R value? Here's the question below for reference. Thank you! A sample of an ideal g...
by Samantha Low 3D
Sat Jan 30, 2021 11:56 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: pOH and pKb
Replies: 5
Views: 37

Re: pOH and pKb

Thank you for posting this! I always get confused about species and surroundings when it comes to pOH and pKb and pH and pKa. This really helped!
by Samantha Low 3D
Sat Jan 30, 2021 11:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Would an aq agent be included in K?
Replies: 27
Views: 82

Re: Would an aq agent be included in K?

Yes, aqueous agents are included when calculating K. K, the equilibrium expression, is calculated from concentrations (concentrations of products to the power of their stoichiometric coefficients over the concentration of the reactants to the power of their respective stoichiometric coefficients), a...
by Samantha Low 3D
Sat Jan 30, 2021 11:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Factors that affect the equilibrium constant
Replies: 25
Views: 61

Re: Factors that affect the equilibrium constant

Temperature is the only factor that we learned affects K value. The direction of change in K value depends if the reaction is exothermic or endothermic. If the temperature increases, K will increase in an endothermic reaction and decrease in an exothermic reaction.
by Samantha Low 3D
Sat Jan 30, 2021 11:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKa and pH
Replies: 6
Views: 44

Re: pKa and pH

Adding on, when the pH of a solution with a weak acid HA is higher than the pka, the charged species A- will become more predominant in the solution. When the pH of a solution with a weak acid HA is lower than the pka, the neutral species HA will become more predominant in the solution. When the pH ...
by Samantha Low 3D
Sat Jan 30, 2021 11:30 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Clarification about Solids & Liquids for Le Chateliers Principle
Replies: 7
Views: 61

Re: Clarification about Solids & Liquids for Le Chateliers Principle

Yes, Le Chatelier's does not apply to pure solids and liquids. We can't increase the concentration of a pure solid or liquid because they are the most concentrated form of the substance. Their effective concentration is constant throughout the reaction. Thus, we do not include pure solids and liquid...
by Samantha Low 3D
Sat Jan 30, 2021 5:50 pm
Forum: Ideal Gases
Topic: Exo vs Endothermic
Replies: 27
Views: 103

Re: Exo vs Endothermic

Combustion reactions reactions (chemical reactions that involve O2 and the formation of CO2 and most of the time H20) are almost always exothermic because they release heat. Hope this helps!
by Samantha Low 3D
Sun Jan 24, 2021 12:14 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Averages of other molecules
Replies: 3
Views: 15

Re: Averages of other molecules

Bond enthalpies are accurate when they are of diatomic molecules, like HCl, O2, or N2, molecules that are only composed of two atoms. When a bond is a part of a molecule, other atoms not directly involved in the bond have influence over the bond strength. For example, the O-H bond in ClOH and BrOH h...
by Samantha Low 3D
Sat Jan 23, 2021 11:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating the pH of a Salt Solution
Replies: 2
Views: 13

Re: Calculating the pH of a Salt Solution

Yes, you are correct! The initial concentration given for NH4Cl was 0.15 M, so the initial concentration for NH4+ would be 0.15 M as well. There is 1 NH4+ cation for ever Cl- anion. However, if the question was asking about 0.15M CaCl2 for example, the initial concentration of Ca would be 0.15M and ...
by Samantha Low 3D
Sat Jan 23, 2021 11:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6A Exercises Question 21
Replies: 2
Views: 7

Re: 6A Exercises Question 21

Hi! Since K w =[H 3 O + ][OH - ] and [H 3 O + ]=[OH - ]=x, we can can say that K w =2.1*10 -14 =x 2 , we solve for x using the square root and get a) x=1.45*10 -7 mol/L=[H 3 O + ] for part b) since we know [H 3 O + ]=[OH - ] and 1.45*10 -7 mol/L=[H 3 O + ], then [OH - ]=1.45*10 -7 mol/L Hope this he...
by Samantha Low 3D
Sat Jan 23, 2021 11:40 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Qudratic Formula
Replies: 19
Views: 106

Re: Qudratic Formula

When using the quadratic formula, I always try to double check that the value inside the square root is never negative. Writing the formula out on paper before I plug it into my calculator helps
by Samantha Low 3D
Sat Jan 23, 2021 11:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Topic 6B Question 11
Replies: 2
Views: 12

Re: Topic 6B Question 11

Hi! Yes, Na2O(s) + H2O (l)--> 2NaOH (aq) is the correct chemical equation based on the scenario of the question. To solve aii): use the molar concentration of OH of the diluted solution you got in part ai) 0.1778M. To find the concentration of OH in the original solution, we can use the formula M1V1...
by Samantha Low 3D
Sat Jan 23, 2021 11:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Studying for Midterm #1
Replies: 63
Views: 181

Re: Studying for Midterm #1

I recommend doing the textbook problems and reviewing notes/outlines as the main basis in studying. If you have time, reading the textbook and going to UA sessions might help!
by Samantha Low 3D
Sun Jan 17, 2021 12:17 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Dynamic
Replies: 4
Views: 38

Re: Equilibrium Dynamic

Temperature is the only factor that affects the K value (equilibrium constant), but equilibriums are dynamic because reactants are constantly going to products and products constantly are going to reactants. These changes occur at the same rate at equilibrium, so we see no net change; however, there...
by Samantha Low 3D
Sat Jan 16, 2021 11:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solvents in Equilibrium Constants
Replies: 3
Views: 14

Solvents in Equilibrium Constants

May someone please clarify on why we don't put solvents in our equilibrium constant calculations? And how do we know if a reactant is a solvent or not?
by Samantha Low 3D
Sat Jan 16, 2021 11:57 pm
Forum: Student Social/Study Group
Topic: Motivation
Replies: 34
Views: 175

Re: Motivation

I think giving myself breaks and having something to look forward to helps me stay motivated! I try to work hard during the weekdays/during the day so I can make time for other important things in my life on the weekends and afternoons+nights. Working at my job also oddly helps me stay motivated and...
by Samantha Low 3D
Sat Jan 16, 2021 11:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Discerning between K
Replies: 2
Views: 22

Re: Discerning between K

Hi! I had this question too, and I learned from chemistry community that K is the equilibrium constant in general, K c is when we're working with concentrations, and K p is for when we are working with partial pressures. When we're working with gasses, it's better to use K p to avoid confusion. We s...
by Samantha Low 3D
Sat Jan 16, 2021 11:34 pm
Forum: Student Social/Study Group
Topic: Comfort Movies
Replies: 128
Views: 343

Re: Comfort Movies

High School Musical is probably my comfort movie, and I really like to watch Community or The Office as good background noise/relax time! Definitely recommend these TV shows when you need mindless entertainment after some tough Chem studying!
by Samantha Low 3D
Sat Jan 16, 2021 11:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 2 #5
Replies: 1
Views: 17

Re: Sapling Week 2 #5

Since we are given Kb and the amine is protenated, we know we are working with a base. In the chemical reaction, B represents the amine. For every mole of OH− produced there is one mole of BH+ produced. Therefore for the aqueous solution [ OH− ] = [ BH+]. First, calculate pOH by doing pOH= 14 - pH. ...
by Samantha Low 3D
Sat Jan 09, 2021 10:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Products and Equilibrium
Replies: 5
Views: 24

Re: Products and Equilibrium

When there are more products than reactants at equilibrium, that means that the reaction favors the right and that the K value will be large. This also means that the products are more stable than the reactants since nature favors the form of lowest energy. Hope this helps!
by Samantha Low 3D
Sat Jan 09, 2021 10:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration
Replies: 12
Views: 81

Re: Concentration

Concentration is moles/liters, and we can't have a negative amount of moles or a negative volume (liters). Thus, the numerator and denominator will always be positive so concentration will always be positive. Hope this helps!
by Samantha Low 3D
Sat Jan 09, 2021 10:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Does K refer to Kc or Kp or both?
Replies: 4
Views: 42

Does K refer to Kc or Kp or both?

Does K refer to Kc or Kp or both? I noticed on table 5G.2, there's K and Kc, so that K probably refers to Kp. However, in the self-check right above this table in the textbook, K is used as the equilibrium constant of an equation without gases, so I infer it refers to Kc? May someone please clarify ...
by Samantha Low 3D
Sat Jan 09, 2021 9:20 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure Changes
Replies: 3
Views: 22

Re: Pressure Changes

Also, it's important to know how the pressure was changed. If the pressure of a reaction vessel increased by adding an inert gas, then the moles of reactant and product and volume are constant. There would be no change in R and P concentration and no effect on reaction. Moreover, it's really the cha...
by Samantha Low 3D
Sat Jan 09, 2021 9:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5H.1b
Replies: 2
Views: 32

Re: 5H.1b

If we set up the equation for K 1 in the original equation, we get: [NH 3 ] 2 /([N 2 ] 1 [H 2 ] 3 ) = 41 If we set up the equation for K 2 in the second equation, we get [NH 3 ] 1 /([N 2 ] 1/2 [H 2 ] 3/2 ) = K 2 Then, we notice that each of the exponents in the second equation is half that of the co...
by Samantha Low 3D
Sat Dec 12, 2020 4:39 pm
Forum: Naming
Topic: 9C.1 Pre-fixes and Suffix Confusion
Replies: 2
Views: 15

Re: 9C.1 Pre-fixes and Suffix Confusion

Peter DePaul 3C wrote:You name it using alphabetical order which is why aqua comes before penta, and it has an -ate on the end because you add -ate to the name if it is a negatively charged compound.


Thank you so much! The alphabetical order thing totally slipped my mind, so that makes a lot more sense.
by Samantha Low 3D
Sat Dec 12, 2020 4:35 pm
Forum: Hybridization
Topic: 2F. 15 What does it mean for S-character to increase?
Replies: 5
Views: 98

Re: 2F. 15 What does it mean for S-character to increase?

Yes, the s-character is quantified just as you explained it. In terms of question 2F.15, it means that bond angle will increase as s-character increases, as an sp2 orbital has 33% s-character, while an sp3 orbital has 25% s-character. Thank you for your help! I don't remember learning about this in...
by Samantha Low 3D
Sat Dec 12, 2020 4:24 pm
Forum: Naming
Topic: Aqua vs Hydrate
Replies: 12
Views: 108

Re: Aqua vs Hydrate

Claire_Kim_2F wrote:What happens if it is anionic is it still aqua or would it be aquate?

I think it would still be aqua. For example, [Co(CN)5(OH2)]2- is an anion and is called aquapentatecyanocobaltate (III) ion.
by Samantha Low 3D
Sat Dec 12, 2020 4:20 pm
Forum: Naming
Topic: 9C.1 Pre-fixes and Suffix Confusion
Replies: 2
Views: 15

9C.1 Pre-fixes and Suffix Confusion

For 9C.1, we are asked to name [Co(CN)5(OH2)]2-. The answer key says that this is called aquapentacyanocobaltate (III) ion. In general, is aqua the only prefix that can come before the numerical prefix (Penta)? Also, can someone help clarify why there an -ate at the end? Thank you!
by Samantha Low 3D
Sat Dec 12, 2020 4:13 pm
Forum: Hybridization
Topic: 2F. 15 What does it mean for S-character to increase?
Replies: 5
Views: 98

2F. 15 What does it mean for S-character to increase?

For number 2F.15, what does it mean when it talks about the s character of hybrids? Is S-character quantifiable? For example, would sp be 50% s and 50% p and sp2 be 33% s-character and 66% p-character? Or is it more of a generalization to describe hybrids?
by Samantha Low 3D
Sat Dec 05, 2020 2:31 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Sapling Homework 9 Problem 2
Replies: 10
Views: 116

Re: Sapling Homework 9 Problem 2

Thank you for posting! I had trouble with this problem too and reading all these responses really helped me. It was very helpful for me to draw the ligands out and count the lone pairs to see if they are monodentate or polydentate. The number of lone pairs it has is the number of bond sites it has. ...
by Samantha Low 3D
Sat Dec 05, 2020 2:18 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Example 9C.1 in Textbook
Replies: 3
Views: 44

Re: Example 9C.1 in Textbook

Thank you! I actually understand that now. So we can find the charge on the TM metal by using the compounds total charge? And we can find the total charge of the compound by adding all the charges of the elements? Yes, we can find the charge on the Transition metal by using the compound's total cha...
by Samantha Low 3D
Sat Dec 05, 2020 2:08 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Monodentate vs. Polydentate
Replies: 3
Views: 49

Re: Monodentate vs. Polydentate

Coordination numbers have to do with the amount of ligands attached to the central atom. For example, [Fe(CN) 6 ] 4- has a coordination number = 6 because it has 6 ligands (CN) - attached to the central atom (Fe). Monodentate and polydentate describes ligands. A monodentate ligand has only one atom ...
by Samantha Low 3D
Sat Dec 05, 2020 1:45 am
Forum: Naming
Topic: 9C3 (a) and (c)
Replies: 2
Views: 25

Re: 9C3 (a) and (c)

(a) Potassium hexacyanidochromate (III) is written as K 3 [Cr(CN) 6 ]. We know that Cr has a charge of +3 because of the Roman numeral (III) we see in its name. We also know that (CN) always has a charge of -1. Since there are six (CN) - and one Cr +3 , the overall charge is [Cr(CN) 6 ] -3 . And sin...
by Samantha Low 3D
Sat Dec 05, 2020 1:25 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectroscopy, Energy level
Replies: 2
Views: 42

Re: Atomic Spectroscopy, Energy level

The energy difference is negative (-4.09 x 10 -19 J) because the electron's energy has decreased (as the electron makes the transition from 4th to 2nd energy level) and the energy is released as electromagnetic radiation.To further calculate, we use a positive value for energy difference because it ...
by Samantha Low 3D
Sun Nov 29, 2020 12:50 am
Forum: Determining Molecular Shape (VSEPR)
Topic: sapling #12
Replies: 13
Views: 115

Re: sapling #12

I think the other replies have great ways to solve this! I just wanted to add that a good way to check might be to check formal charges to make sure you get the most stable form and have full octet where needed. Hope this helps!
by Samantha Low 3D
Sun Nov 29, 2020 12:40 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling #3 Bond Angle
Replies: 8
Views: 87

Re: Sapling #3 Bond Angle

Using the VSEPR model, we find out that this molecule is square pyramidal. We know that square pyramidal is close to octahedral, except one atom is replaced by a lone pair in square pyramidal. In octahedral, the smallest angle is 90 degrees. Since there is a lone pair in square pyramidal, there is m...
by Samantha Low 3D
Sun Nov 29, 2020 12:24 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling HW #18
Replies: 7
Views: 62

Re: Sapling HW #18

When they ask about relative positions, I think they are talking about the positions of atoms in relation to one another in a 3D space, using the lewis structure to help create the model. Lewis structures are 2D, but the actual model of the molecule is in 3D. For instance, the lewis structure for CH...
by Samantha Low 3D
Sat Nov 28, 2020 10:42 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Lecture #24 Ligands and Complexes
Replies: 5
Views: 38

Re: Lecture #24 Ligands and Complexes

marisagaitan1G wrote:Octahedral wouldn't make sense if the atom is forming four bonds, so I'm pretty sure he meant tetrahedral or square planar.


Thank you! This really helped clear up some confusion!
by Samantha Low 3D
Sat Nov 28, 2020 10:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Clarification on Shape vs Arrangement
Replies: 5
Views: 45

Re: Clarification on Shape vs Arrangement

Lone pairs do influence molecular shape because of repulsion. For instance, even though, CO 2 and H 2 O both have 3 atoms, CO 2 is linear while H 2 O is bent because H 2 O has two lone pairs. CO 2 has a linear molecular geometry and linear electron arrangement while H 2 O has bent molecular geometry...
by Samantha Low 3D
Wed Nov 25, 2020 2:03 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Lecture #24 Ligands and Complexes
Replies: 5
Views: 38

Lecture #24 Ligands and Complexes

Around 31:17 of Lecture #24, Professor Lavelle says, "If there are four bonds, well then, it's either going to be square planar and tetrahedral, and you will not be expected to know which it is. You will be expected to know that if there is four bonds, it's either octahedral or square planar.&q...
by Samantha Low 3D
Sun Nov 22, 2020 3:43 pm
Forum: Resonance Structures
Topic: Resonance Structures and Energy
Replies: 21
Views: 125

Re: Resonance Structures and Energy

Yes, this is why we try to get the structures with least formal charges, least formal charge magnitudes, and the formal charges on the most electronegative atoms.
by Samantha Low 3D
Sun Nov 22, 2020 3:29 pm
Forum: Resonance Structures
Topic: 2.7 Resonance of N5 cation
Replies: 2
Views: 41

Re: 2.7 Resonance of N5 cation

First, I add up all the electrons that the structure has. Then, like you, I add single bonds and later double and triple bonds if I am electron deficient. I like to use formal charge to make sure I am on the right track-- trying to get the least number and magnitudes of formal charges and making sur...
by Samantha Low 3D
Sun Nov 22, 2020 3:15 pm
Forum: Bond Lengths & Energies
Topic: kJ/mol for bond energy in Lecture #18
Replies: 3
Views: 68

Re: kJ/mol for bond energy in Lecture #18

I was confused about this too, and the way I think about it is that it takes 20kJ to break 1 mole of hydrogen bonds, so it would take 200kJ to break 10 mole of hydrogen bonds. I think of the 20kJ/mole as a ratio, and that helps me compare with other ratios for strengths of intermolecular interaction...
by Samantha Low 3D
Sun Nov 22, 2020 3:05 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi Bond Lecture
Replies: 7
Views: 38

Re: Sigma and Pi Bond Lecture

Sahiti Annadata 2A wrote:I believe it is discussed in Lecture 22.

Thank you!
by Samantha Low 3D
Sun Nov 22, 2020 3:04 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi Bond Lecture
Replies: 7
Views: 38

Re: Sigma and Pi Bond Lecture

Mingzi Yang 1H wrote:Sigma and Pi bonds are discussed in lecture 22.

Thank you!
by Samantha Low 3D
Sun Nov 22, 2020 3:04 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi Bond Lecture
Replies: 7
Views: 38

Re: Sigma and Pi Bond Lecture

Eva Becker wrote:Hi! Sigma and Pi Bonds are discussed in Dr. Lavelle's most recent lecture from November 20th (Lecture 22).

Thank you! I totally forgot that I didn't finish that lecture because it didn't load. I'll make sure to watch!
by Samantha Low 3D
Sun Nov 22, 2020 2:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T Shape Structure
Replies: 2
Views: 42

Re: T Shape Structure

It is highly unfavorable for the lone-lone interactions/lone-bond interactions/bond-bond to be 90° apart. If the lone pairs were in axial positions, then there would be six 90° bond pair - lone pair interactions. If BF 3 was arranged in the T-shape molecular structure with trigonal bipyramidal elect...
by Samantha Low 3D
Sun Nov 22, 2020 2:37 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi Bond Lecture
Replies: 7
Views: 38

Sigma and Pi Bond Lecture

Hi! I was looking through my notes, and I realized that I didn't have any on sigma and pi bonds. I thought I watch all the lectures, but I don't remember learning about sigma and pi bonds. Which lecture were sigma and pi bonds discussed in?
by Samantha Low 3D
Sun Nov 15, 2020 10:29 pm
Forum: Lewis Structures
Topic: Homework Problem 2C.5
Replies: 2
Views: 16

Re: Homework Problem 2C.5

This is a great question! I'm not really sure myself so I'm commenting to come back to this. If I had to give my best guess, I would say it is because oxygen is more electronegative than Chlorine, so it would make more sense for Oxygen to complete it's octet. Thanks for asking this question!
by Samantha Low 3D
Sun Nov 15, 2020 10:19 pm
Forum: Dipole Moments
Topic: Topic 3F Exercises Question 19
Replies: 2
Views: 19

Re: Topic 3F Exercises Question 19

Vapor pressure or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature in a closed system. When more liquid evaporates, there is a higher vapor pressure. You are correct that water has stronger interact...
by Samantha Low 3D
Sun Nov 15, 2020 10:13 pm
Forum: Dipole Moments
Topic: Hydrogen Bonding Lone pairs
Replies: 3
Views: 19

Re: Hydrogen Bonding Lone pairs

Also, an N,O, or F atom can form more than one hydrogen bond depending on how many lone pairs it has. For instance, in molecule with an O that has two lone pairs, that O can form 2 hydrogen bonds.
by Samantha Low 3D
Fri Nov 13, 2020 8:25 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: melodie zaki worksheet
Replies: 2
Views: 23

Re: melodie zaki worksheet

I had trouble picturing this, so here is an image that helped me :)
Image
by Samantha Low 3D
Fri Nov 13, 2020 8:18 pm
Forum: Sigma & Pi Bonds
Topic: Triple bond?
Replies: 21
Views: 169

Re: Triple bond?

I had the same question! Thank you for posting, I definitely have a better understanding now.
by Samantha Low 3D
Sun Nov 08, 2020 2:55 am
Forum: Formal Charge and Oxidation Numbers
Topic: Sapling Week 5-6 # 12
Replies: 4
Views: 46

Re: Sapling Week 5-6 # 12

Thank you for posting this! At first, I was stuck thinking oxidation state was the same as formal charge, but this post really cleared up. Thank you!!
by Samantha Low 3D
Sun Nov 08, 2020 2:40 am
Forum: Resonance Structures
Topic: Sapling HW Question 4
Replies: 5
Views: 48

Re: Sapling HW Question 4

Here is a visual to what others are explaining. Hope this helps!
by Samantha Low 3D
Sun Nov 08, 2020 2:35 am
Forum: Resonance Structures
Topic: Sapling #4 weeks 5-6
Replies: 2
Views: 33

Re: Sapling #4 weeks 5-6

Here is a visual. Hope this helps!
by Samantha Low 3D
Sun Nov 08, 2020 2:17 am
Forum: Student Social/Study Group
Topic: Studying From Home
Replies: 91
Views: 570

Re: Studying From Home

I like to make myself coffee or tea while I study. I think it helps me just get in the zone and feel some sense of normalcy. If you are able too, I would also recommend going outside to study with study music. I feel like ambiance of the outdoors and music give a nice background noise.
by Samantha Low 3D
Sun Nov 08, 2020 2:11 am
Forum: Ionic & Covalent Bonds
Topic: Homework Problem 2A.5
Replies: 2
Views: 21

Re: Homework Problem 2A.5

Cu+ is a Cu atom that has lost an electron. The ground state configuration for Cu is [Ar]4s 2 3d 9 . However, the ground state configuration for Cu+ is [Ar]3d 10 . The ground state configuration for Cu+ is not [Ar]4s 2 3d 8 because it is more stable to have a full 3d orbital, which is lower in energ...
by Samantha Low 3D
Sun Nov 01, 2020 5:40 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: l=4
Replies: 13
Views: 85

Re: l=4

Thank you for posting! I had the same question and I had trouble wrapping my head around l. This forum definitely helped.
by Samantha Low 3D
Sun Nov 01, 2020 5:35 pm
Forum: Student Social/Study Group
Topic: How to relax
Replies: 125
Views: 711

Re: How to relax

It was great to read everyone's comments! Now I guess I have more things to do. I usually just go on short hikes or at least take a break and watch the sunset to relax:)
by Samantha Low 3D
Sun Nov 01, 2020 5:30 pm
Forum: Student Social/Study Group
Topic: Favorite TV shows
Replies: 189
Views: 1206

Re: Favorite TV shows

If you like crime that's not too gory, I would recommend White Collar or Psych! I used to be afraid to watch criminal minds/bones/castle (but I've come to love them!!), so White Collar and Psych were really great :)
by Samantha Low 3D
Sat Oct 31, 2020 10:38 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration of Silver
Replies: 3
Views: 46

Re: Electron Configuration of Silver

Thank you for posting! I always get confused on how the energy orbitals fill up, so I started using this chart. Hope this helps!
Image
by Samantha Low 3D
Sat Oct 31, 2020 10:35 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: HW #23
Replies: 3
Views: 34

Re: HW #23

When writing ground state electron configurations, orbitals are filled starting with the lowest energy level. Since Carbon has 6 electrons, we start by filling the 1s and 2s orbitals. Now we have 2 electrons to put in the next energy level, 2p. So, the ground state configuration should be 1s^2 2s^2 ...
by Samantha Low 3D
Sat Oct 31, 2020 1:31 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 3d and 4s Orbital
Replies: 3
Views: 36

Re: 3d and 4s Orbital

Thank you for posting this, I had the same question!
by Samantha Low 3D
Sun Oct 25, 2020 11:04 pm
Forum: SI Units, Unit Conversions
Topic: nanometer conversion
Replies: 6
Views: 83

Re: nanometer conversion

The conversion is 1 m = 10^9 nm. I think about it as moving the decimal place over, and I do the conversion in my calculator. Hope this helps!
by Samantha Low 3D
Sun Oct 25, 2020 7:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Even Solutions to Textbook Questions
Replies: 3
Views: 35

Even Solutions to Textbook Questions

Is there a place where we can find solutions to the even numbered problems in the textbook?
by Samantha Low 3D
Sun Oct 25, 2020 6:27 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Textbook Question 1B.25
Replies: 4
Views: 81

Re: Textbook Question 1B.25

Thanks for posting this question and thank you to everyone for answering! I was stuck on this problem trying to figure out why they used an equation different from the Heisenberg uncertainty formula we are used to.
by Samantha Low 3D
Sat Oct 24, 2020 11:30 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: How to measure uncertainty in an experiment
Replies: 2
Views: 52

Re: How to measure uncertainty in an experiment

That's a really good question. If I'm reading it right, I think the uncertainty you are mentioning has to do with error. I wasn't sure were scientists got +/- certain values for experiments, so I looked it up. It looks like there is a formula to help come up with values for uncertainty from the data...
by Samantha Low 3D
Sat Oct 24, 2020 9:42 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg’s Constant
Replies: 6
Views: 80

Re: Rydberg’s Constant

I have the same question too! When I was doing one of the sapling problems, I looked at the solution and they said "because this is an emission, the beginning energy level is equal to n=2 and the ending is equal to n=1" if we are using the equation below. So, according to sapling, I would ...
by Samantha Low 3D
Sat Oct 24, 2020 9:27 pm
Forum: Properties of Electrons
Topic: Question 12 on sapling week 2
Replies: 4
Views: 57

Re: Question 12 on sapling week 2

The Rydberg constants are equivalent; they just have different units. One is in Hz and the other is in m^-1. 3.28984 *10^15 Hz = 1.097*10^7 m^-1. We get 1.097*10^7 m^-1 by doing 3.28984 *10^15 Hz/3.00 x 10^8 m/s. We know c= λv, so we use this idea to convert between the two Rydberg constants. I thin...
by Samantha Low 3D
Sun Oct 18, 2020 11:23 pm
Forum: Properties of Light
Topic: Sampling #8
Replies: 1
Views: 21

Re: Sampling #8

First, start by converting the wavelength to meters. Then, find how many J are needed to melt the ice by doing 451g * (enthalpy of fusion) to get x. Next, use the equation E(photon) = (hc)/( λ) to find the energy of each photon. Then, set x = (number of photons)*(E(photon)) and rearrange to get numb...
by Samantha Low 3D
Sun Oct 18, 2020 9:36 pm
Forum: Properties of Electrons
Topic: Energy Level Dropping
Replies: 5
Views: 63

Re: Energy Level Dropping

I believe that when an electron starts at the fourth energy level, it has been excited to that level and is now going back down. Also, if the electron moves from n=4 to n=2 for example, that electron will eventually go back to the ground state. Thank you! That makes sense. Just to clarify, would th...
by Samantha Low 3D
Sun Oct 18, 2020 9:28 pm
Forum: Properties of Light
Topic: Wave properties of light
Replies: 4
Views: 69

Re: Wave properties of light

I had the same question too, so I looked it up a little bit. Light does have wave properties, but it can also be viewed a photons. One way wave properties are shown is in the double slit experiment, where incident light has a refraction pattern from interference characteristic of light waves rather ...
by Samantha Low 3D
Sun Oct 18, 2020 6:26 pm
Forum: Properties of Light
Topic: Sapling homework question 5
Replies: 3
Views: 45

Re: Sapling homework question 5

First, start by converting the wavelength to meters. Then, use the equation E(photon) = (hc)/( λ) to find the energy of each photon. Next, set 14.48 J = (number of photons)*(E(photon)) and rearrange to get number of photons = 14.48J/(E(photon)). I had a slightly different problem, but I was able to ...
by Samantha Low 3D
Sun Oct 18, 2020 5:31 pm
Forum: Properties of Electrons
Topic: Energy Level Dropping
Replies: 5
Views: 63

Re: Energy Level Dropping

I believe that when an electron starts at the fourth energy level, it has been excited to that level and is now going back down. Also, if the electron moves from n=4 to n=2 for example, that electron will eventually go back to the ground state. Thank you! That makes sense. Just to clarify, would th...
by Samantha Low 3D
Sun Oct 18, 2020 5:17 pm
Forum: Properties of Electrons
Topic: Energy Level Dropping
Replies: 5
Views: 63

Energy Level Dropping

If a problem asks about the frequency of a light emitted by a hydrogen atom when an electron when an electron makes a transition from the fourth to the second principal quantum level, does this mean that an electron can just drop to the second energy level and stop or is this drop to the second ener...
by Samantha Low 3D
Sun Oct 11, 2020 12:00 am
Forum: SI Units, Unit Conversions
Topic: Angstrom vs. pm +Solutions Manual
Replies: 4
Views: 67

Re: Angstrom vs. pm +Solutions Manual

Hi, I also found that on sapling under "resources" there is a pdf labeled "Atkins 7e SSM" that has the solutions to the book problems as well. Also if you want to check your work I found that if you copy and paste the question just in google the questions likely already been ask...
by Samantha Low 3D
Sat Oct 10, 2020 11:58 pm
Forum: SI Units, Unit Conversions
Topic: Mnemonic
Replies: 6
Views: 62

Re: Mnemonic

I remember it as K.H.D.U.D.C.M : King Henry Doesn't Usually Drink Chocolate Milk. Or Kilo, Hecto, Deca, Unit (for example: gram), Deci, Centi, Mili. Hope this helps! I remembered it pretty much the same, just a little more morbid haha. T.G.M.K.H.D.U.D.C.M.M.N.P: That (Tera) Great (giga) Morning (Me...
by Samantha Low 3D
Sat Oct 10, 2020 4:51 pm
Forum: SI Units, Unit Conversions
Topic: Angstrom vs. pm +Solutions Manual
Replies: 4
Views: 67

Re: Angstrom vs. pm +Solutions Manual

Hi! I don't think there is any separate solution manual for this textbook. If you go to the back of the textbook, there should be solutions to some of the fundamental questions there. Also, there are some errors in the textbook's solutions so Dr. Lavelle has a solution manual for those incorrectly ...
by Samantha Low 3D
Fri Oct 09, 2020 11:55 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook L. 35
Replies: 3
Views: 88

Re: Textbook L. 35

Thank you for this post! I didn't realize there was an error.
by Samantha Low 3D
Fri Oct 09, 2020 11:52 pm
Forum: SI Units, Unit Conversions
Topic: Angstrom vs. pm +Solutions Manual
Replies: 4
Views: 67

Angstrom vs. pm +Solutions Manual

Hi! I'm looking to check my work, and I've seen people on here reference the "solution manual"? Is that something we had to buy separate or does it come with the book? If it comes with the book, where do I find it? Also, do we use angstroms or pm when we deal with atoms? Thank you for your...
by Samantha Low 3D
Fri Oct 09, 2020 11:47 pm
Forum: SI Units, Unit Conversions
Topic: Fundamental L.37
Replies: 2
Views: 48

Re: Fundamental L.37

Thank you for posting, I was stuck on this one too!
by Samantha Low 3D
Fri Oct 09, 2020 3:44 pm
Forum: SI Units, Unit Conversions
Topic: Practice Problem 1B #5 Units Tip [ENDORSED]
Replies: 4
Views: 192

Re: Practice Problem 1B #5 Units Tip [ENDORSED]

Thank you for posting this! I was very confused about the units and approaching this problem as well.

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