## Search found 116 matches

Sun Mar 14, 2021 5:09 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3 Part (d) Question [ENDORSED]
Replies: 1
Views: 33

### 6L.3 Part (d) Question[ENDORSED]

Hi everyone! For part (d) of this problem, the only way that we would be able to figure out the oxidation reaction that occurs at the anode is if it was provided for us correct? I'm not sure how you would be able to write it out with just the information provided by the table. 6L.3(d): Pt(s)|O2(g)|H...
Sat Mar 13, 2021 10:15 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 8
Views: 30

### Cell Diagrams

Hi everyone!

For cell diagrams, I know that the convention is to put the solid electrodes at the end of the cell diagrams and to separate each phase by a single line, however, would the order matter between each phase when we write out the cell diagram?

Thank you!
Fri Mar 12, 2021 10:56 pm
Forum: First Order Reactions
Topic: Focus Exercise 7.25
Replies: 1
Views: 46

### Focus Exercise 7.25

Hi everyone! I was very confused on how to approach this problem and come up with an explanation, so I was wondering if you guys could explain your thought process on how you guys understood this question? 2.25: Vision depends on the protein rhodopsin, which absorbs light in the retina of the eye in...
Fri Mar 12, 2021 10:53 pm
Forum: First Order Reactions
Topic: Focus Exercise 7.27
Replies: 2
Views: 25

### Focus Exercise 7.27

Hi everyone! I was wondering if you guys could explain how you guys approached this problem, and how we should approach problems like these in the future? Would we start off by finding the rate constant from the first-order half-life equation using the 4.5 hours? What would we do after that? 7.27: T...
Fri Mar 12, 2021 10:49 pm
Forum: Second Order Reactions
Topic: Focus Exercise 7.21
Replies: 2
Views: 38

### Focus Exercise 7.21

Hi everyone! I don't really remember Dr. Lavelle discussing the plots for situations from part (e) to (h), so I was wondering if you guys could explain the conceptual meaning and relationships behind these plots and how we would know if they are linear or not? 7.21: Which of the following plots will...
Sun Mar 07, 2021 9:37 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Focus Exercise 6.65
Replies: 1
Views: 21

### Focus Exercise 6.65

Hi everyone!

I was a little confused on how to approach this problem, so I was wondering if you guys could explain how you started the problem?

6.65: What range (in volts) does a voltmeter need to have to measure pH in the range of 1 to 14 at 25 °C if the voltage is zero when pH = 7?

Thank you!
Sun Mar 07, 2021 9:35 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Focus Exercise 6.61
Replies: 2
Views: 26

### Focus Exercise 6.61

Hi everyone! I was a little confused about this problem, and I was wondering if you guys could elaborate on the conceptual aspect of problems like these? 6.61: In a neuron (a nerve cell), the concentration of K+ ions inside the cell is about 20–30 times as great as that outside. What potential diffe...
Sun Mar 07, 2021 9:30 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Focus Exercise 6.53
Replies: 1
Views: 25

### Focus Exercise 6.53

Hi everyone! I was wondering if you guys could explain to me how to figure out each part of this problem? I'm still a little iffy on the conceptual aspect of electrochemistry, so I'm having trouble understanding this problem. 6.53: (a) If you were to construct a concentration cell in which one half-...
Sat Mar 06, 2021 8:52 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6N.17 Question
Replies: 1
Views: 15

### 6N.17 Question

Hi everyone! I was wondering if you guys could explain to me how you approached this question? I'm also still confused about the relationship between work and cell potential, so I was wondering if you guys could elaborate on that as well? 6N.17: Consider the cell Ag(s)|Ag+(aq, 5.0 mmol⋅L−1)||Ag+(aq,...
Thu Mar 04, 2021 1:32 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Focus Exercise 6.57
Replies: 1
Views: 32

### Focus Exercise 6.57

Hi everyone! I was wondering how you guys figured out what the other half-reaction would be based on the information that is given? We're usually given a full equation where we could figure out our half-reactions, but I'm not sure what I should do in this type of situation. 6.57: Use the data in App...
Thu Mar 04, 2021 12:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6O.3 Question
Replies: 4
Views: 36

### 6O.3 Question

Hi everyone! I was wondering if you guys could explain to me how we would approach this problem? I'm a little confused as to how to start it off. 6O.3: Aqueous solutions of (a) Mn2+; (b) Al3+; (c) Ni2+; (d) Au3+ with concentrations of 1.0 mol⋅L−1 are electrolyzed at pH = 7. For each solution, determ...
Thu Mar 04, 2021 11:37 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.9 Question
Replies: 2
Views: 28

### 6N.9 Question

Hi everyone! For this problem, I was wondering how you guys figured out which one was the anode and which one was the cathode? Also, after we figure this out, how would we continue approaching the problem? 6N.9: A tin electrode in 0.015 M Sn(NO3)2(aq) is connected to a hydrogen electrode in which th...
Wed Mar 03, 2021 3:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M.7 Question
Replies: 1
Views: 15

### 6M.7 Question

Hi everyone! I was wondering if you guys could explain to me how we would know whether one reducing agent would be stronger than another reducing agent? In addition, how would we know whether one oxidizing agent is stronger than another oxidizing agent? 6M.7: Arrange the following metals in order of...
Sun Feb 28, 2021 8:43 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox Reactions
Replies: 6
Views: 29

### Balancing Redox Reactions

Hi everyone!

When we're balancing redox reactions, how would we know where to place the H2O in order to balance the O in the half-reactions?

Thank you!
Sun Feb 28, 2021 7:13 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: How Electricity is Quantified
Replies: 3
Views: 33

### How Electricity is Quantified

Hi everyone!

There was a sapling question that asked about how electricity was quantified, and I was wondering if you guys could explain to me what the difference between charge, current, and potential was?

Thank you!
Thu Feb 25, 2021 5:20 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Sapling Weeks 7 and 8 Question 17
Replies: 4
Views: 52

### Sapling Weeks 7 and 8 Question 17

Hi everyone! I was wondering if you guys could explain to me how we would approach question 17? I'm not sure how we would start the problem with the information given. Question 17: What would the potential of a standard hydrogen electrode (S.H.E.) be under the given conditions? [H+]=0.47 M PH2=1.9 a...
Thu Feb 25, 2021 10:12 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Sapling Weeks 7 and 8 Question 12
Replies: 4
Views: 53

### Sapling Weeks 7 and 8 Question 12

Hi everyone! For this sapling problem, I'm not sure why my answer was incorrect, so I was wondering if you guys could explain it to me? I had determined that the 2Au^3+(aq) + 6e- -> 2Au(s) was the reduction half-reaction and the other one was the oxidation half-reaction. Then, to find the E° value, ...
Thu Feb 25, 2021 8:27 am
Forum: Balancing Redox Reactions
Topic: Oxidizing Agent and Reducing Agent
Replies: 7
Views: 58

### Oxidizing Agent and Reducing Agent

Hi everyone! I noticed that in multiple sapling problems, it would often ask for the "oxidizing agent" and "reducing agent," but I got a little confused when I was inputting the answers. I was wondering if you guys could explain why the species being reduced is called the "o...
Wed Feb 24, 2021 8:44 pm
Forum: Balancing Redox Reactions
Topic: Sapling Weeks 7 and 8 Question 3
Replies: 3
Views: 42

### Sapling Weeks 7 and 8 Question 3

Hi everyone! I was wondering if you guys could explain to me how we would convert from an acidic solution to a basic solution? So far, I have 2Cu^2+ + 2e- -> 2Cu+ and Cr + 2e- + 4H2O -> CrO4^2- + 8H+ for the half-reactions, but I'm not sure where I should go on from there. Question 3: For a particul...
Thu Feb 18, 2021 7:48 pm
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: Sapling Weeks 5 and 6 Question #1
Replies: 5
Views: 53

### Sapling Weeks 5 and 6 Question #1

Hi everyone! I was a little confused about the answer to this question, which states that only NO and N2O would have a residual entropy. Why wouldn't CO2 also have a residual entropy? I remember Dr. Lavelle comparing CO2(g) vs. He(g) during one of the lectures, and he said that CO2(g) would have a h...
Thu Feb 18, 2021 1:24 pm
Forum: Calculating Work of Expansion
Topic: Irreversible vs. Reversible
Replies: 6
Views: 79

### Irreversible vs. Reversible

Hi everyone! I was wondering if you guys could explain to me the difference between an irreversible expansion vs. a reversible expansion, and which work equation corresponds with which type of expansion? At first, I thought that the difference between the two was that an irreversible expansion start...
Thu Feb 18, 2021 8:46 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Perfect System
Replies: 3
Views: 34

### Perfect System

Hi everyone!

I was wondering if you guys could explain to me how we would be able to recognize whether a system is a perfect system or not to apply the concept of qsys+qsurr = 0?

Thank you!
Thu Feb 18, 2021 8:41 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Bomb Calorimeter
Replies: 14
Views: 160

### Bomb Calorimeter

Hi everyone!

Is a bomb calorimeter considered a perfect system?

Thank you!
Thu Feb 18, 2021 8:35 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Concept of qsys=-qsurr
Replies: 7
Views: 87

### Concept of qsys=-qsurr

Hi everyone!

I was wondering if you guys could explain the concept of qsys=-qsurr and how we could recognize when to apply this concept to a problem that is given?

Thank you!
Sun Feb 14, 2021 8:23 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 4.45 Question
Replies: 1
Views: 15

### 4.45 Question

Hi everyone! I was wondering if you guys could explain the reasoning for each of the parts of this problem because I'm having trouble applying the concepts to the actual problem itself. 4.45: Potassium nitrate dissolves readily in water, and its enthalpy of solution is +34.9kJ⋅mol^−1. (a) Does the e...
Sun Feb 14, 2021 5:55 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Overall Concept of the Second Law of Thermodynamics
Replies: 1
Views: 33

### Overall Concept of the Second Law of Thermodynamics

Hi everyone!

I was wondering if you guys could explain the concept of the second law of thermodynamics? I know how to apply the equation to problems most of the time, but I don't really understand the conceptual idea of the second law of thermodynamics.

Thank you so much!
Sun Feb 14, 2021 2:11 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 4J.13 Question
Replies: 3
Views: 28

### 4J.13 Question

Hi everyone! I was wondering if you guys could explain when we would know whether a compound is stable from looking at their standard free energies of formation? 4J.13: Determine which of the following compounds are stable with respect to decomposition into their elements under standard conditions a...
Fri Feb 12, 2021 9:03 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 4H.1 Question
Replies: 1
Views: 30

### 4H.1 Question

Hi everyone! I was wondering if you guys could explain to me the concept of molar entropy, and how we would determine whether something has a higher molar entropy than another thing? 4H.1: Which substance in each of the following pairs has the higher molar entropy at 298 K: (a) HBr(g) or HF(g); (b) ...
Fri Feb 12, 2021 8:26 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.17 Question
Replies: 3
Views: 85

### 4F.17 Question

Hi everyone! I was wondering if you guys could explain what your thought process was when going through problems like these, and how we should approach it in the future? 4F.17: Calculate the standard entropy of vaporization of water at 85 °C, given that its standard entropy of vaporization at 100.°C...
Thu Feb 11, 2021 4:48 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Sapling Weeks 5 and 6 Question #14
Replies: 3
Views: 29

### Sapling Weeks 5 and 6 Question #14

Hi everyone! I was wondering if you guys could explain how you approached this question? What equation would we use to find the boiling point of a compound in general? Question 14: The ΔHvap of a certain compound is 47.10 kJ·mol^−1 and its ΔSvap is 85.33 J·mol^−1·K^−1. What is the boiling point of t...
Thu Feb 11, 2021 4:43 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Sapling Weeks 5 and 6 Question #7
Replies: 2
Views: 53

### Sapling Weeks 5 and 6 Question #7

Hi everyone! I was a little confused as to how to approach this problem, so I was wondering if you guys could explain how to start off the problem? What would we use to calculate the molar enthalpy of vaporization and molar entropy of vaporization? Question 7: Three liquid samples of known masses ar...
Sat Feb 06, 2021 5:47 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Focus Exercise 4.17
Replies: 3
Views: 36

### Focus Exercise 4.17

Hi everyone! For this problem, I was wondering if you guys could explain how to find the answer to part (c) of the question? How would we be able to find the number of moles when the reaction goes to completion for part (c)? 4.17: A technician carries out the reaction 2SO2(g)+O2(g)→2SO3(g) at 25 °C ...
Sat Feb 06, 2021 5:42 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Focus Exercise 4.15
Replies: 1
Views: 23

### Focus Exercise 4.15

Hi everyone! I was wondering if you guys could explain to me how to approach this problem? I'm having trouble on how to approach problems like these. 4.15: Hydrochloric acid oxidizes zinc metal in a reaction that produces hydrogen gas and chloride ions. A piece of zinc metal of mass 8.5 g is dropped...
Thu Feb 04, 2021 6:45 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4C.13 Question
Replies: 3
Views: 30

### 4C.13 Question

Hi everyone! I was a little confused as to how to approach these types of problems, so I was wondering if you guys could explain to me how you guys would approach a problem like this? 4C.13: An ice cube of mass 50.0 g at 0.0°C is added to a glass containing 400.0 g of water at 45.0°C. What is the fi...
Thu Feb 04, 2021 10:48 am
Forum: Administrative Questions and Class Announcements
Topic: Sapling Weeks 3,4,5 Grade Error
Replies: 4
Views: 48

### Sapling Weeks 3,4,5 Grade Error

Hi everyone! I just finished my sapling that is due on Sunday of Week 5, but for some reason, the grade book only lists my sapling grade as a 95% instead of 100%. Usually, my sapling grade is updated right away after I finish the assignment, so I was wondering if anyone else had this problem with yo...
Thu Feb 04, 2021 9:40 am
Forum: Calculating Work of Expansion
Topic: 4B.13 Question
Replies: 1
Views: 17

### 4B.13 Question

Hi everyone! For these types of problems, I was wondering if you guys could explain the difference between an irreversible expansion and an isothermal, reversible expansion and how we would calculate them using the information given from the problem? 4B.13: Calculate the work for each of the followi...
Thu Feb 04, 2021 9:09 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy Question
Replies: 8
Views: 65

### Internal Energy Question

Hi everyone!

I was wondering how we would know whether the internal energy would be a negative value or a positive value?

Thank you!
Thu Feb 04, 2021 8:35 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: 4A.9 Question
Replies: 2
Views: 16

### 4A.9 Question

Hi everyone! I was a little confused on how to approach problems like these, so I was wondering if you guys could explain to me your thought process when you do these types of problems? 4A.9: A piece of copper of mass 20.0 g at 100.0 °C is placed in a vessel of negligible heat capacity but containin...
Wed Feb 03, 2021 8:20 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sapling Weeks 3,4,5 Question 20
Replies: 2
Views: 22

### Sapling Weeks 3,4,5 Question 20

Hi everyone! For this question, I tried approaching it by first using PV=nRT to find the R constant. Then, based on the table given for molar heat capacity at constant volume (which I have included below), I multiplied the R constant by 5/2 because CO2(g) is a linear molecule. After this, I plugged ...
Wed Feb 03, 2021 6:41 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sapling Weeks 3,4,5 Question 19
Replies: 3
Views: 45

### Sapling Weeks 3,4,5 Question 19

Hi everyone! I was a little confused as to how to approach this question, so I was wondering if you guys could explain this in more detail as to how to approach the specific question and questions like these in general? Question 19: A constant‑volume calorimeter was calibrated by carrying out a reac...
Sun Jan 31, 2021 5:45 pm
Forum: Calculating Work of Expansion
Topic: Work on the Surroundings
Replies: 3
Views: 24

### Work on the Surroundings

Hi everyone!

How would we know if a system is doing work on the surroundings at constant pressure based on the chemical equations?

Thank you!
Sun Jan 31, 2021 5:09 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sapling Weeks 3,4,5 Question 12
Replies: 5
Views: 45

### Sapling Weeks 3,4,5 Question 12

Hi everyone! I was wondering if you guys could explain how you guys approached question 12 on the sapling homework. I was a little confused as to where to start. Question 12: At constant volume, the heat of combustion of a particular compound, compound A, is −3850.0 kJ/mol. When 1.063 g of compound ...
Sun Jan 31, 2021 4:21 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sapling Weeks 3,4,5 Question 10
Replies: 1
Views: 51

### Sapling Weeks 3,4,5 Question 10

Hi everyone! I was a little confused as to how to approach 10 on the sapling homework and I was wondering if you guys could explain to me how you guys did it? Question 10: An ice cube with a mass of 47.2 g at 0.0 ∘C is added to a glass containing 425 g of water at 45.0 ∘C. Determine the final temper...
Fri Jan 29, 2021 6:01 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Stable Form in Enthalpies of Formation
Replies: 11
Views: 43

### Stable Form in Enthalpies of Formation

Hi everyone!

How would we know if something is in its most stable form to use the standard enthalpy of formation? I know that H2(g), O2(g), N2(gas), HCl(g), HBr(g), and C(s) are in their most stable forms, but how would you tell for other elements?

Thank you!
Fri Jan 29, 2021 5:58 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Phase Change in Bond Enthalpies
Replies: 1
Views: 22

### Phase Change in Bond Enthalpies

Hi everyone! I remember Dr. Lavelle telling us that when we use the bond enthalpy method to find the enthalpy, we have to add the enthalpy of the phase change for liquids and solids. The example that he gave was Br2(l) -> 2Br(g), which meant that we had to add the enthalpy of vaporization (liquid ->...
Thu Jan 28, 2021 5:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Significant Figures when Doing Ice Table Problems
Replies: 3
Views: 23

### Significant Figures when Doing Ice Table Problems

Hi everyone! I noticed that in the solutions manual for the icebox textbook problems, it often calculates its value with the correct amount of significant figures throughout the whole process. However, I usually calculate it using the entire values and then round to the significant figures to the en...
Sun Jan 24, 2021 11:53 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4E.5 Question
Replies: 2
Views: 27

### 4E.5 Question

Hi everyone! For this part (b) of this problem, I was confused as to why the solutions manual multiplied the bond enthalpy values of CH4 and CCl3 by 4 moles when there is only a coefficient of 1 in front of those compounds in the chemical equation, which would indicate that they are 1 mole right? I ...
Sun Jan 24, 2021 7:08 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.15 Question
Replies: 2
Views: 24

### 4D.15 Question

Hi everyone! I was a little confused about how to approach this question, and I was wondering if you guys could explain this to me? 4D.15: Determine the reaction enthalpy for the hydrogenation of ethyne to ethane, C2H2(g)+2H2(g)→C2H6(g), from the following data: ΔHc(C2H2,g)=−1300.kJ⋅mol−1, ΔHc°(C2H6...
Sat Jan 23, 2021 11:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating the pH of a Salt Solution
Replies: 2
Views: 14

### Calculating the pH of a Salt Solution

Hi everyone! For the example that Dr. Lavelle gave in one of the earlier lectures regarding calculating the pH for the salt, NH4Cl, I understand that the salt dissociates into NH4+ and Cl-, and we leave out Cl- because it's the conjugate base of a strong acid. However, would the NH4+ that we use to ...
Sat Jan 23, 2021 10:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.29 Question
Replies: 1
Views: 12

### 5I.29 Question

Hi everyone! When we're trying to determine the equilibrium partial pressures, would the same icebox method for finding the equilibrium composition be applied? Are there any extra steps that we would have to do if the reaction vessel does not have a volume of 1.0 L? 5I.29: At 25 °C, K=3.2×10^−34 for...
Sat Jan 23, 2021 10:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13 Question
Replies: 1
Views: 16

### 5I.13 Question

Hi everyone! For this question, I was wondering if you guys could explain how we would be able to determine which element is thermodynamically more stable relative to its atoms at a certain temperature? This was part (c) in question 5I.13. 5I.13: (a) In an experiment, 2.0 mmol Cl2(g) was sealed into...
Sat Jan 23, 2021 10:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between K and Kc
Replies: 13
Views: 84

### Difference between K and Kc

Hi everyone! For some of the textbook exercises, we had to reference Table 5G.2 for the equilibrium constant, and I was wondering what the difference between K and Kc was? Would Kc just be the equilibrium constant when we refer specifically to concentration, and if so, what would K represent sepcifi...
Fri Jan 22, 2021 3:32 pm
Forum: Administrative Questions and Class Announcements
Topic: Outline 3 and Midterm Questions
Replies: 1
Views: 31

### Outline 3 and Midterm Questions

Hi everyone! Do you guys know which problems we should focus on from Outline 3 for the first midterm? I know that Dr. Lavelle told us to focus on reading 4D.3-4D.5 and 4E.3, but I don't think that covers all the 4D textbook questions, so I was wondering if you guys knew? Also, do you guys know how m...
Sat Jan 16, 2021 11:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6E.3 Question
Replies: 2
Views: 27

### 6E.3 Question

Hi everyone! For this problem, I was a little confused about what they meant by second deprotonation, so I was wondering if you guys could explain that to me? In addition, why can we ignore the second deprotonation if the approximation is justified? 6E.11: Calculate the pH of each of the following s...
Sat Jan 16, 2021 11:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6E.1 Question
Replies: 1
Views: 19

### 6E.1 Question

Hi everyone!

I was unsure of how to start this problem, so I was wondering if you guys could explain it to me? I have included the table with the Ka values below.

6E.1: Calculate the pH of 0.15 M H2SO4(aq) at 25 °C.

Thank you so much!
Fri Jan 15, 2021 11:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constants to Predict Solubility
Replies: 2
Views: 39

### Equilibrium Constants to Predict Solubility

Hi everyone! For one of the bullet points on Outline 1, it says that we should be able to "use equilibrium constants to predict solubility." I don't remember Dr. Lavelle discussing this in the lectures, so I was wondering if you guys could explain how we would be able to predict solubility...
Fri Jan 15, 2021 9:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 2 - Question 5
Replies: 1
Views: 16

### Sapling Week 2 - Question 5

Hi everyone! For this question, I was a little confused on how to set it up because the initial concentration isn't given? I thought that we would need the initial concentration to set up an ice table and calculate the percentage that is protonated, so I was wondering if you guys could explain this ...
Wed Jan 13, 2021 5:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6B.11 Question
Replies: 2
Views: 25

### 6B.11 Question

Hi everyone! I was a little confused about how to start this problem, and I was wondering if you guys could explain it to me? 6B.11: A student added solid Na2O to a volumetric flask of volume 200.0 mL, which was then filled with water, resulting in 200.0 mL of NaOH solution. Then 5.00 mL of the solu...
Fri Jan 08, 2021 1:53 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature Effect on the Direction of the Reaction
Replies: 4
Views: 25

### Temperature Effect on the Direction of the Reaction

Hi everyone!

I'm a little confused on how we apply whether a reaction is exothermic or endothermic to the direction that the reaction will proceed when there is a temperature change. I was wondering if you guys could explain it to me?

Thank you!
Fri Jan 08, 2021 9:22 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium Part 2 Post Module #30
Replies: 2
Views: 20

### Chemical Equilibrium Part 2 Post Module #30

Hi everyone! I was a little unsure on how to carry out question 30 on the post-module assessment for Chemical Equilibrium Part 2, and I was wondering if you guys could explain this to me? Would I first covert the 2.5 moles H2O and 100 g of C into molarity. Then, place them in an ice box and work fro...
Fri Jan 08, 2021 9:18 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium Part 2 Post Module #29
Replies: 1
Views: 35

### Chemical Equilibrium Part 2 Post Module #29

Hi everyone! I was unsure of how to set up this problem, and I was wondering if you guys could explain it to me? #29: A researcher fills a 1.00 L reaction vessel with 1.84 x 10^-4 mol of BrCl gas and heats it to 500 K. At equilibrium, only 18.3 % of the BrCl gas remains. Calculate the equilibrium co...
Fri Jan 08, 2021 9:02 am
Forum: Administrative Questions and Class Announcements
Topic: Sapling Error - Did Question 10 reset?
Replies: 3
Views: 50

### Sapling Error - Did Question 10 reset?

Hi everyone! Yesterday, I finished my sapling homework for Week 1, and it even gave me the notification (with the bunny) indicating that I have answered all the questions in the activity. My grade was also recorded in the CCLE gradebook as 5/5. However, today, when I went back on sapling to review t...
Thu Jan 07, 2021 7:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Focus Exercise 5.39 Question
Replies: 2
Views: 75

### Focus Exercise 5.39 Question

Hi everyone! For this question, I was wondering if the solutions manual was incorrect when calculating the Kc, which is a value that we would need to find x. Table 5G.2, which I have included below, shows that the reaction N2O4(g) ⇌ 2NO2 has a Kc value of 6.1x10^23. Therefore, I thought that the Kc ...
Thu Jan 07, 2021 5:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 1 - Question 9
Replies: 2
Views: 52

### Sapling Week 1 - Question 9

Hi everyone! For question 9 on the sapling homework, I was wondering if you guys could explain to me how to set up the ice box correctly. I had originally set up the ice box with 0.700 as the initial condition for NO and 0.300 as the initial conditions for N2 and O2. Then, I added x to both the N2 a...
Sat Dec 12, 2020 4:34 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals and Their Nodal Planes
Replies: 5
Views: 61

### Orbitals and Their Nodal Planes

Hi everyone!

I was wondering if you guys could explain to me how we can determine the number of nodal planes in an orbital? I know that the s orbital has no nodal planes, but how would we know how many nodal planes there will be for the other orbitals?

Thank you so much!
Sat Dec 12, 2020 11:14 am
Forum: Naming
Topic: Oxidation Numbers
Replies: 3
Views: 31

### Oxidation Numbers

Hi everyone! I had a general question about oxidation numbers. When we're determining the oxidation number for the transition metal, are we taking into account the whole compound or do we just take into account the coordination compound. I had always done the latter, but when I was reviewing Dr. Lav...
Wed Dec 09, 2020 8:04 am
Forum: Identifying Acidic & Basic Salts
Topic: Neutralization Reactions
Replies: 2
Views: 31

### Neutralization Reactions

Hi everyone!

I noticed that in the textbook problems, neutralization reactions were mentioned multiple times, and I was wondering if you guys could explain what they were?

Thank you so much!
Wed Dec 09, 2020 8:00 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Indeterminacy Concept
Replies: 1
Views: 26

### Heisenberg Indeterminacy Concept

Hi everyone!

Could you guys explain to me the overall concept of the Heisenberg Interdeterminacy Principle? I understand how to calculate a Heisenberg problem when I see it, but I don't really understand the concept behind it.

Thank you so much!
Mon Dec 07, 2020 8:26 am
Forum: Lewis Acids & Bases
Topic: Identifying Acids and Bases
Replies: 5
Views: 80

### Identifying Acids and Bases

Hi everyone! I'm having trouble identifying acids and bases in general, and I was wondering if you guys could explain how to distinguish the two? I know that acids would usually have an H and bases would usually have an OH, but what other characteristics are there to tell whether something is an aci...
Sun Dec 06, 2020 9:05 pm
Forum: Amphoteric Compounds
Topic: 6A.17 Question
Replies: 3
Views: 49

### 6A.17 Question

Hi everyone!

I was wondering if you guys could explain to me how to distinguish whether an oxide is acidic, basic, or amphoteric?

6.17: State whether the following oxides are acidic, basic, or amphoteric: (a) BaO; (b) SO3; (c) As2O3; (d) Bi2O3.

Thank you so much!
Sat Dec 05, 2020 11:14 am
Forum: Conjugate Acids & Bases
Topic: 6A.1 Question
Replies: 1
Views: 43

### 6A.1 Question

Hi everyone! I was wondering if you guys could explain to me how to determine the conjugate acid and conjugate base when asked in a problem? 6A.1: Write the formulas of the conjugate acids of (a) CH3NH2, methylamine; (b) NH2NH2, hydrazine; (c) HCO3−; and the conjugate bases of (d) HCO3−; (e) C6H5OH,...
Tue Dec 01, 2020 1:58 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Focus Exercise 2.27
Replies: 4
Views: 47

### Focus Exercise 2.27

Hi everyone! For this problem, I understand that none of the compounds given are considered radicals because they do not have an unpaired electron. I was a little confused by the answer that the solution manual gave for part (b) of this problem, which states that "all of these species are expec...
Tue Dec 01, 2020 1:48 pm
Forum: Naming
Topic: Naming Coordination Compounds
Replies: 4
Views: 51

### Naming Coordination Compounds

Hi everyone!

In the textbook, there is a table in Focus 9 that shows the names and formulas of common ligands, and I was wondering if we would need to memorize those common ligands when naming coordination compounds? I included an image of the table below.

Thank you!
Tue Dec 01, 2020 1:43 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 9C.5 Question
Replies: 4
Views: 70

### 9C.5 Question

Hi everyone! I'm still a little confused on how we distinguish when a ligand is a polydentate vs. when it's a monodentate, and I was wondering if you guys could explain it to me. Would it be a polydentate if there are multiple ligands with lone pairs in the compound? I have included the problem belo...
Sun Nov 29, 2020 8:34 pm
Forum: Hybridization
Topic: 2F.15 Question
Replies: 3
Views: 33

### 2F.15 Question

Hi everyone! I was wondering if you guys could explain to me what the s-character of hybrids meant for this problem? 2F.15: Noting that the bond angle of an sp3 hybridized atom is 109.5° and that of an sp2 hybridized atom is 120°, do you expect the bond angle between two hybrid orbitals to increase ...
Sun Nov 29, 2020 5:40 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelates General Question
Replies: 2
Views: 25

### Chelates General Question

Hi everyone!

I was a little confused on when and how chelates are formed. During the lecture, I was confused when Dr. Lavelle was explaining about chelating ligands in general, and I was wondering if you guys could summarize it for me?

Thank you so much!
Sun Nov 29, 2020 7:49 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Bond Angles
Replies: 9
Views: 82

### Determining Bond Angles

Hi everyone!

Whenever a question asks us to determine bond angles, would the bond angles always correspond to the molecular shape? For example, if the molecular shape is linear, the bond angle will always be 180°?

Thank you!
Sun Nov 29, 2020 7:45 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Molecular Shape General Question
Replies: 2
Views: 46

### Determining Molecular Shape General Question

Hi everyone! When we're determining the shape of a more complex compound like, C2H4 or N2H4, would we just look about the two central atoms to determine the molecular shape? For example, the molecular shape for C2H4 would be trigonal planar about the C atom. I was wondering if you guys could explain...
Sun Nov 29, 2020 7:40 am
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.29 Question
Replies: 3
Views: 64

### 2E.29 Question

Hi everyone! When determining which isomer in this problem is polar or nonpolar, would we just have to look at the dipole moments? Since the 3rd isomer has the two chorines direct opposite from each other, does this mean that the dipole moments cancel out? I was wondering if you guys could explain m...
Tue Nov 24, 2020 5:50 am
Forum: Administrative Questions and Class Announcements
Topic: CHEM 14B Enrollment Question
Replies: 2
Views: 61

### CHEM 14B Enrollment Question

Hi everyone!

I noticed that some discussion spots opened up for CHEM 14B, however, it is listed as "no instructors," so I was wondering if you guys knew what this meant?

Thank you so much!
Sun Nov 22, 2020 11:05 pm
Forum: Hybridization
Topic: Hybridization General Question
Replies: 2
Views: 16

### Hybridization General Question

Hi everyone!

I was a little confused about hybridizations, so I was wondering if you guys could clarify the concept for me? Why would we need hybridizations?

Thank you so much!
Sun Nov 22, 2020 10:21 pm
Forum: Sigma & Pi Bonds
Topic: Sigma & Pi Bonds General Question
Replies: 2
Views: 23

### Sigma & Pi Bonds General Question

Hi everyone!

I was wondering when would we need to distinguish between sigma and pi bonds? Are there specific situations where it asks us to determine the difference between sigma and pi bonds?

Thank you so much!
Thu Nov 19, 2020 8:36 am
Forum: Resonance Structures
Topic: Resonance Hybrids
Replies: 2
Views: 46

### Resonance Hybrids

Hi everyone! I was wondering if you guys could explain to me what resonance hybrids are? Is the resonance hybrid the combination of all the resonance structures that we draw for that molecule? In addition to this, when we're looking at a resonance hybrid, are the bond lengths all the same even thoug...
Thu Nov 19, 2020 8:29 am
Forum: Coordinate Covalent Bonds
Topic: Identifying Lewis Acid and Lewis Base
Replies: 3
Views: 76

### Identifying Lewis Acid and Lewis Base

Hi everyone! I was wondering if you guys could clarify with me on how to identify lewis acids and bases for compounds that do not have a charge? I understand that, usually, lewis acids could have a positive charge, which means that they accept the electrons, while lewis bases have a negative charge,...
Tue Nov 17, 2020 9:32 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability and Polarizing Power
Replies: 5
Views: 33

### Polarizability and Polarizing Power

Hi everyone!

I was wondering if you guys could explain to me what polarizability is and how we would determine what has a bigger polarizing power when comparing cations or anions? I didn't really understand this concept.

Thank you so much!
Sun Nov 15, 2020 6:17 pm
Forum: Dipole Moments
Topic: Dipole-Dipole Moment General Question
Replies: 5
Views: 54

### Dipole-Dipole Moment General Question

Hi everyone!

I was wondering if you guys could explain to me how to recognize when a molecule has a dipole-dipole moment? Is it when there's a partially positive and partially negative region because one atom has a much higher electronegativity than the other atom?

Thank you so much!
Sun Nov 15, 2020 10:07 am
Forum: Bond Lengths & Energies
Topic: Bond Length & Strength Comparison
Replies: 3
Views: 31

### Bond Length & Strength Comparison

Hi everyone! I had a question regarding the comparison of bond lengths. I understand that single bonds are the longest and weakest in strength, while triple bonds are the shortest and strongest in strength. However, what would we do if we are asked to compare the bond length and strength in a situat...
Sat Nov 14, 2020 5:52 pm
Forum: Dipole Moments
Topic: 3F.15 Question
Replies: 2
Views: 18

### 3F.15 Question

Hi everyone!

I was wondering if you guys could explain how to describe the difference in the boiling points between these two compounds?

Problem 3F.15: Explain the difference in the boiling points of AsF3 (63)°C and AsF5 (−53)°C.

Thank you so much!
Fri Nov 13, 2020 9:27 pm
Forum: Dipole Moments
Topic: 3F.5 Question
Replies: 2
Views: 22

### 3F.5 Question

Hi everyone! I was wondering if you guys could help me on part (c) of this problem? I was a little confused by the answer because they used LDF when they compared the two molecules, and I was wondering why we wouldn't be able to use dipole-dipole in this situation? Problem 3F.5: Suggest, giving reas...
Fri Nov 13, 2020 9:17 pm
Forum: Lewis Structures
Topic: Lewis Structures Method
Replies: 2
Views: 19

### Lewis Structures Method

Hi everyone!

I was wondering if you guys could share some tips and methods on how to draw lewis structures. For harder molecules, I sometimes get confused about which atoms to connect and where to add a double bond or triple bond.

Thank you so much!
Sun Nov 08, 2020 5:46 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A.11 Question
Replies: 2
Views: 16

### 2A.11 Question

Hi everyone!

I was a little confused on how to approach this problem, so I was wondering if you guys could help me on this?

2A.11: Which M^3+ ions (where M is a metal) are predicted to have the following ground-state electron configurations: (a) [Ar]3d^6; (b) [Ar]3d^5?

Thank you!
Sun Nov 08, 2020 5:41 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration for Ions
Replies: 1
Views: 16

### Electron Configuration for Ions

Hi everyone! When we are writing electron configurations for ions, and the ion has the same amount of electrons as a noble gas, can we write the electron configuration as the noble gas? For example, if we have S^2-, this would have the same electrons as Ar, so could we write its electron configurati...
Sun Nov 08, 2020 12:31 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence Electrons vs. Outer Electrons
Replies: 4
Views: 37

### Valence Electrons vs. Outer Electrons

Hi everyone! I had a question regarding valence electrons and outer electrons. Are these considered the same thing? I went to a step-up session during the week, and one of the questions asked to define the core electrons, outer electrons, and valence electrons for different elements, and for some el...
Sun Nov 08, 2020 12:27 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A.1 Question
Replies: 1
Views: 26

### 2A.1 Question

Hi everyone! I had a quick question about this problem in the textbook. For part (a), why would we not include the electrons in the 4d orbital as the valence electrons for the element Sb? 2A.1: Give the number of valence electrons (including d electrons) for each of the following elements: (a) Sb; (...
Sun Nov 08, 2020 12:14 am
Forum: Trends in The Periodic Table
Topic: Effective Nuclear Charge
Replies: 3
Views: 28

### Effective Nuclear Charge

Hi everyone!

I was a little confused about the concept of effective nuclear charge, and I was wondering if you guys could clarify what it is and explain when we would need to use it?

Thank you so much!
Sun Nov 01, 2020 12:14 pm
Forum: Trends in The Periodic Table
Topic: Focus Exercise 1.13
Replies: 2
Views: 22

### Focus Exercise 1.13

Hi everyone! I was wondering if you guys could explain why the ionization energy for oxygen is lower than that of either nitrogen or fluorine? 1.13: Ionization energies usually increase on going from left to right across the periodic table. The ionization energy for oxygen, however, is lower than th...
Sun Nov 01, 2020 12:10 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 1E. 17 Question
Replies: 4
Views: 33

### 1E. 17 Question

Hi everyone! I was a little confused on how to approach this problem, and I was wondering if you guys could help me with this question? Question 1E.17: For each of the following ground-state atoms, predict the type of orbital (1s, 2p, 3d, 4f, etc.) from which an electron will be removed to form the ...
Sun Nov 01, 2020 12:04 pm
Forum: Trends in The Periodic Table
Topic: Sapling Weeks 2,3,4 Homework #18
Replies: 4
Views: 36

### Sapling Weeks 2,3,4 Homework #18

Hi everyone!

I'm still a little confused on the periodic trends for the ionic radius, and I was wondering if you guys could explain the trend to me and help me with this question?

Question #18: Arrange these ions according to the ionic radius. P^3- S^2- Cl^- K^+ Ca^2+

Thank you so much!
Tue Oct 27, 2020 10:22 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: General Heisenberg Question
Replies: 7
Views: 103

### General Heisenberg Question

Hi everyone! In Heisenberg problems, will there be instances where we're given a +/- with a percentage? For example, can the problem give us an uncertainty for position as 5.00 +- 1%, or would there always be an actual number after the +- sign? I understand that in theory, we would have to double it...
Tue Oct 27, 2020 10:18 am
Forum: Properties of Light
Topic: 1A.3 Question
Replies: 3
Views: 54

### 1A.3 Question

Hi everyone! For this question, I understood why the other answer options were incorrect, but I didn't really understand what the correct answer was saying. I was wondering if you guys could explain it to me? Question 1A.3: Which of the following happens when the frequency of electromagnetic radiati...