## Search found 71 matches

Sun Mar 17, 2019 4:06 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Plot of Arrhenius function
Replies: 4
Views: 478

### Plot of Arrhenius function

The x-axis would be 1/t for this Arrhenius plot. What would the y-axis be?
Sun Mar 17, 2019 4:04 pm
Forum: First Order Reactions
Topic: Slopes of a plot
Replies: 7
Views: 726

### Slopes of a plot

Is the slope of a plot of a first order negative?
Sun Mar 17, 2019 4:02 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal energy change
Replies: 1
Views: 316

### Internal energy change

How do you calculate the change of internal energy given heat capacity of a calorimeter and the final and initial temperatures?
Mon Mar 11, 2019 10:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Constructing cell diagrams
Replies: 2
Views: 124

### Constructing cell diagrams

From test 2, problem 4 wants us to construct a cell diagram of the balanced cell reaction NO3-(aq)+4H+(aq)+Fe(s)->NO(g)+2H2O(l)+Fe^3+(aq). I know the anode goes on the left and cathode on the right. Is Fe(s)|Fe3+(aq)||NO3-(aq)|NO(g)|Pt(s) correct? Or do you need to put H+ and H2O in there too??
Sat Mar 09, 2019 5:46 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow step
Replies: 2
Views: 96

### Slow step

In lecture on Friday, Dr. Lavelle showed us an example and asked us which step was the slow step. How do we identify which is the slow step?
Sat Mar 09, 2019 5:40 pm
Forum: Zero Order Reactions
Topic: Textbook Examples
Replies: 1
Views: 108

### Textbook Examples

Are there any textbook problems involving zeroth order that we can do as examples?
Thu Mar 07, 2019 8:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Determining stability?
Replies: 1
Views: 114

### Determining stability?

5I.13 asks to determine if Cl2 or F2 is more thermodynamically stable relative to its atoms. The answer is Cl2. How is that so? We solved that the F2 reaction has an equilibrium constant of 1.2x10^-4 and the Cl2 rxn had 1.3x10^-7 Kc.
Tue Mar 05, 2019 6:04 pm
Forum: First Order Reactions
Topic: How to calculate [A]t in 7B.3 7th ed
Replies: 1
Views: 113

### How to calculate [A]t in 7B.3 7th ed

In part C, we’re asked to calculate the rate constant for the rate loss of A from 2A->B+C given that [A]0=0.153 mol/L and that after 115s give the the concentration of B rises to 0.034 mol/L. To do this, I know we have to uses ln([A]t/[A]0)=-kt. But first we need to come of with [A]t. The solutions ...
Tue Mar 05, 2019 3:16 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Which experimented do you use to find rate constant?
Replies: 2
Views: 180

### Which experimented do you use to find rate constant?

In 7A.17 from the 7th edition, part c asks us to determine the value of the rate constant. In the examples from the book, it seemed like they just picked one of the experiments and plugged that into the rate law reaction and it worked. For 17 though, it seems like you have to choose “the right” expe...
Sun Mar 03, 2019 3:19 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Large K value
Replies: 5
Views: 256

### Large K value

The book says a reaction with a large positive Ecell°has K>>1. What does this mean?
Sun Mar 03, 2019 3:15 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: The Nernst equation
Replies: 2
Views: 176

### The Nernst equation

Does temperature always have to be in kelvin for the Nernst equation?
Sun Mar 03, 2019 3:13 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation
Replies: 1
Views: 115

### Nernst Equation

How do you distinguish what to plug in for Ecell versus Ecell°? How do you know which one is which?
Thu Feb 21, 2019 6:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.3 7th ed. Write the half reactions and balanced equation for the cell reaction.
Replies: 2
Views: 159

### 6L.3 7th ed. Write the half reactions and balanced equation for the cell reaction.

in part a) Ni|Ni2+||Ag+|Ag we need to write the balanced equation. I understand how to do this, but the solution manual shows for each half reaction what the E°(cathode) and E°(anode) is. How did they come up with these values?
Thu Feb 21, 2019 4:26 pm
Forum: Balancing Redox Reactions
Topic: Reducing agents and oxidizing agents
Replies: 6
Views: 320

### Re: Reducing agents and oxidizing agents

Sarah Kiamanesh 1D wrote:reducing agents bring about reduction by becoming oxidized and giving up their electrons
oxidizing agents bring about oxidation by becoming reduced and accepting electrons

So whatever is oxidized is the reducing agent? And whatever is reduced is the oxidizing agent?
Wed Feb 20, 2019 7:07 pm
Forum: Balancing Redox Reactions
Topic: 6k.5 7th ed. Writing half reaction for basic solution
Replies: 1
Views: 109

### 6k.5 7th ed. Writing half reaction for basic solution

For part a) we need to balance the skeletal equation O3+Br- ---> O2+BrO3- using oxidation and reduction half reactions taking place in a basic solution. Would O3-->O2 be oxidizing or is that a reduction? I think it's oxidizing, but later when the solutions shows the half reaction, it gives H2O+O3+ 2...
Wed Feb 20, 2019 6:56 pm
Forum: Balancing Redox Reactions
Topic: Reducing agents and oxidizing agents
Replies: 6
Views: 320

### Reducing agents and oxidizing agents

Is the element that's being reduced the reducing agent or the oxidizing agent? What is a reducing or oxidizing agent?
Sat Feb 16, 2019 12:03 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous vs boiling point?
Replies: 4
Views: 264

### Spontaneous vs boiling point?

In class on Friday, we covered an example that asked what temp Br2(l)->Br2(g) would be spontaneous at 1 ATM? The professor said that this is the same thing as asking what the boiling point is. Can someone explain this? I understand going from a liquid to a gas would involve boiling, but why does tha...
Sat Feb 16, 2019 12:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Midterm Ice Table
Replies: 6
Views: 317

### Midterm Ice Table

For one of the questions on the midterm, did we need to use approximations when calculating x? I got confused because I thought the problem needed it but I remember in class we were told there would be no approximation based questions.
Sat Feb 16, 2019 11:57 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Test 2
Replies: 3
Views: 187

### Test 2

Is test 2 going to be covering thermodynamics? Or is it going to be on electrochemistry?
Sun Feb 10, 2019 5:03 pm
Forum: Calculating Work of Expansion
Topic: Derivations of formulas
Replies: 1
Views: 111

### Derivations of formulas

Are we going to need to know how to derive certain formulas on the midterm? In class Dr. Lavelle seemed to spend some time deriving them out but only the final equation helps solve the question?
Thu Feb 07, 2019 3:45 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.11 when to use Cvln(T2/T1) vs nRln(T2/T1)
Replies: 2
Views: 177

### Re: 4F.11 when to use Cvln(T2/T1) vs nRln(T2/T1)

In the end, it shouldn't matter which equation you use to find the change in entropy. I believe that ΔS=nR ln(T2/T1) was used over ΔS=Cv ln(T2/T1) simply because it you can derive the number of moles (using PV=nRT) more easily than trying to find the heat capacity. If you can find the heat capacity...
Wed Feb 06, 2019 11:11 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.11 when to use Cvln(T2/T1) vs nRln(T2/T1)
Replies: 2
Views: 177

### 4F.11 when to use Cvln(T2/T1) vs nRln(T2/T1)

For question 4F.11 we're asked to calculate the change of entropy of a gas where there was 3 L of N2 at 18.5 degrees Celsius compressed to 0.5 L. In the process the temp increased to 28.1 degrees Celsius. I know we have to calculate the change of entropy for both the volume and temperature change an...
Wed Feb 06, 2019 9:41 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Midterm content
Replies: 2
Views: 104

### Midterm content

On the class website, it says the midterm will cover content to the end of entropy, does that mean the material till the end of section 4F (titled entropy) in the Textbook, or all the sections passed that that involve more information about entropy as well?
Sat Feb 02, 2019 5:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpies
Replies: 3
Views: 216

### Bond enthalpies

On problem 4E.5 part a, it asks to calculate the reaction enthalpy using bond enthalpies for the reaction 3C2H2->C6H6 The table in the book gives what I’m assuming is a resonance bond enthalpy for benzene's Carbon single and double bonds. Before noticing that, I did 3(348)+3(612) which is for the si...
Tue Jan 29, 2019 7:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.23 7th Ed.
Replies: 1
Views: 126

### 4D.23 7th Ed.

The question asks to calculate the standard enthalpy formation of dinitrogen pentoxide from the info: 2NO+O2–>2NO2 delta H= -114.1kJ 4NO2+O2->2N2O5 delta H= -110.2 kJ I’m confused on how to do this. The solutions show to add the first reaction with half of the second, but why are you allowed to mult...
Tue Jan 29, 2019 6:42 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Replies: 3
Views: 165

The lectures seem to be out of order compared to the Textbook outlines. By now, which sections of the Textbook (7th edition) have we read, and which homework problems should we be able to know how to do? There seems to be a lot of jumping around even within the sections.
Sat Jan 26, 2019 12:15 am
Forum: Phase Changes & Related Calculations
Topic: Severe burn from steam clarification
Replies: 5
Views: 1636

### Severe burn from steam clarification

As mentioned in class, a burn from 100 degree steam is more severe than that of 100 degree water. Is the reason for that because it takes longer for the steam to cool compared to water?
Sat Jan 26, 2019 12:12 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Changing sign of enthalpy
Replies: 3
Views: 119

### Changing sign of enthalpy

When you have a chemical equation and you take the reverse reaction, why does delta H change sign to negative if it was originally positive and vice versa?
Sat Jan 26, 2019 12:08 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess’s Law
Replies: 2
Views: 109

### Hess’s Law

Can someone explain how to do problem 4d.19 from the 7th edition step by step? It asks to calculate the reaction enthalpy for H2 + Br2 -> 2HBr given the following data: NH3 + HBr-> NH4Br delta H= -188.32 kJ., also given N2+3H2->2NH3 delta H=-92.22 kJ, and given N2+4H2+Br2->2NH4Br delta H= -541.66 kJ...
Thu Jan 17, 2019 6:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.3 7th ed, calculating Ka and pKa
Replies: 1
Views: 71

### 6D.3 7th ed, calculating Ka and pKa

I have two questions about 6D.3. It asks to find the Ka and pKa values given the information that you have 0.10 M HClO2 with pH 1.2. In the solutions it shows that the concentration of H3O is 0.06 mol/L which is solved by taking 10^-pH in this case 10^-1.2. I understand that, but then they say that ...
Tue Jan 15, 2019 6:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium Part 3 Post-Assessment
Replies: 1
Views: 117

### Chemical Equilibrium Part 3 Post-Assessment

Can someone explain how to solve number 20 on the post-assessment 3? I understand how to set up the table but why in the given table for the equilibrium concentration do they say c+2x for 2SO3 and not just 2x. How do you solve for the c? A vial of SO2 (0.522 mol.L-1) and O2 (0.633 mol.L-1) react and...
Mon Jan 14, 2019 10:21 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pH question
Replies: 3
Views: 111

### pH question

On 6B.3 part B (7th ed) it asks what the actual pH of a solution would be when a lab technician wants to prepare 200 mL of a 0.025 M HCL solution but uses a volumetric flask of 250 mL by mistake. The solutions show that you take the -log((200mL x 0.025M)/250 mL)= 1.7. Can someone explain this work o...
Mon Jan 14, 2019 9:15 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Autoprotolysis
Replies: 3
Views: 135

### Autoprotolysis

Autoprotolysis, as defined in the book, is a type of reaction where one molecule transfers a proton to another molecule of the same kind. Is this specific to just H2O or is it any of the same two molecules?
Sat Jan 12, 2019 4:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solving for x in ICE table
Replies: 2
Views: 122

### Solving for x in ICE table

On question 5I.17 in the 7th ed., there is a step in the solutions manual that goes from 2x=(3.16x10^-3)(0.114-x) followed by the step 2.00316x=3.60x10^-4. Can someone explain the work process in between those steps or how to get from that first step to the next?
Fri Jan 11, 2019 9:37 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Converting Kc to Kp
Replies: 4
Views: 693

### Converting Kc to Kp

How do I convert from Kc to Kp or vice versa?
Fri Jan 11, 2019 9:33 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chem equilibrium module 2
Replies: 1
Views: 71

### Chem equilibrium module 2

For the last question on module 2, “The reaction 2 SO2 (g) + O2 (g) ⇌ 2 SO3 (g) occurs in a 1.00 L flask at 312 K and at equilibrium the concentrations are 0.075 mol.L-1 SO2 (g), 0.537 mol.L-1 O2 (g), and 0.925 mol.L-1 SO3 (g). Calculate their respective partial pressures at 312 K using R = 8.206 × ...
Fri Jan 11, 2019 9:31 am
Forum: Ideal Gases
Topic: What does K represent?
Replies: 9
Views: 354

### Re: What does K represent?

K is the equilibrium constant. It represents the concentration of products at equilibrium over the concentration of reactants at equilibrium. At equilibrium the reaction is still occuring and products and reactants are still being formed/ the forward and reverse reactions are stil occuring but at eq...
Sun Dec 09, 2018 3:09 pm
Forum: Naming
Topic: Naming question with anion
Replies: 2
Views: 389

### Naming question with anion

How do you know whether to add -o -ido or -ato to the end of an anions name vs leaving it as is?
Sat Dec 08, 2018 5:42 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining the Coordination number
Replies: 3
Views: 85

### Re: Determining the Coordination number

I believe it is determined by the number of atoms which can body to the central atom.
Sat Dec 08, 2018 5:06 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Churro question 38
Replies: 1
Views: 283

### Churro question 38

How do we know that H2Se has a greater boring point than H2S considering that they both have LDF and dipole dipole?
Mon Dec 03, 2018 4:49 pm
Forum: Identifying Acidic & Basic Salts
Topic: Determining if a salt is basic or acidic?
Replies: 1
Views: 162

### Determining if a salt is basic or acidic?

In problem 6D.11 7th edition, it asks to decide whether an aqueous solution off each of the following salts has a pH equal to, less than 7, or greater than 7. If pH>7 or pH<7 then write a chemical equation to justify the answer. a) NH4Br b) Na2CO3 c) KF d) KBr e)AlCl3 f)Cu(NOs)2.Can someone please e...
Sun Dec 02, 2018 5:11 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 3
Views: 93

### Polydentate

How can I tell if something is polydentate? And how do I decide if it's mono dentate, bidentate, trident ate etc.? I understand polydentate means that the ligand binds at multiple sites but, how can we figure out how many sites it binds to?
Sat Dec 01, 2018 4:10 pm
Forum: Naming
Topic: 9C.1 7th Ed. Homework question naming
Replies: 1
Views: 110

### 9C.1 7th Ed. Homework question naming

On part c) given [Co(CN)5(OH2))]2- the name is aquapentacyanocobaltate(iii) ion. Why is it cobaltate and not just cobalt, while on the next part d) we have [Co(NH3)5(SO4)]+ the name is pentaamminesulfatocobalt(iii) ion. here we have Co written as cobalt not cobaltate. How do you know which one to use?
Sat Dec 01, 2018 3:54 pm
Forum: Naming
Topic: CN naming?
Replies: 3
Views: 70

### CN naming?

When would I name something Cyano vs Cyanido?
Sat Dec 01, 2018 2:39 pm
Forum: Naming
Topic: Naming/ oxidation numbers/ charges
Replies: 2
Views: 117

### Naming/ oxidation numbers/ charges

Can anyone explain how to know what the oxidation number is when naming a coordination compound? I think it has to do with the overall charge of the compound, but then how do you also know what the charge of the compound is?
Sun Nov 25, 2018 2:24 am
Forum: Hybridization
Topic: Test 3
Replies: 13
Views: 350

### Test 3

Will we need to know how to draw the hybridized orbitals for the test?
Sat Nov 24, 2018 3:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Incomplete octet
Replies: 2
Views: 82

### Incomplete octet

Are there any other elements or examples like Boron Trifluoride where the central atom can have an incomplete octet like boron does? Besides the first four elements of the periodic table (which never have a complete octet)
Sat Nov 24, 2018 3:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape of BF3
Replies: 1
Views: 144

### Shape of BF3

When drawing the Lewis structure for Boron Trifluoride, why do we allow it to have an incomplete octet? I get that adding a lone pair to the Boron would mess up its formal charge, but why can it then have an incomplete octet? This impacts determining the molecular shape because it involves regions o...
Sat Nov 17, 2018 9:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: No central atom
Replies: 7
Views: 289

### No central atom

When you have a molecule that doesn't really have a central atom i.e. N2H4, how do you determine the shape?
Sat Nov 17, 2018 8:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Model
Replies: 3
Views: 135

### VSEPR Model

Do we need know the notation for vsepr (AXE)?
Sat Nov 17, 2018 7:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape vs electron geometry
Replies: 4
Views: 168

### Molecular shape vs electron geometry

What is the difference when asked for molecular shape versus electron geometry?
Sun Nov 11, 2018 2:15 pm
Forum: Limiting Reactant Calculations
Topic: Chem Community Points
Replies: 3
Views: 416

### Re: Chem Community Points

I believe it must be at least three posts per week due by Sunday nights. I don't think posting more in one week will compensate for posts you've missed in the past.
Sun Nov 11, 2018 2:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR determining shape
Replies: 3
Views: 150

### VSEPR determining shape

How do you figure out the shape of a compound? Is it just based off of the number of bonding pairs on the central atom?
Sun Nov 11, 2018 1:05 pm
Forum: Ionic & Covalent Bonds
Topic: Determining ionic character vs covalent
Replies: 3
Views: 171

### Re: Determining ionic character vs covalent

I believe you subtract the electronegativity of Phosphorus from that of Chlorine since chlorine is more electronegative. Thus it would be 3.16-2.19=0.97 electronegativity difference.
Sat Nov 03, 2018 1:12 pm
Forum: Lewis Structures
Topic: Lewis Structures of acids and bases
Replies: 1
Views: 62

### Lewis Structures of acids and bases

In the 7th edition 2C.3 the question asks, draw the lewis structure including typical contributions to resonance structure for (b) hydrogen phosphate ion, (c) chloric acid. I am confused as to why in part (b) the solution shows the hydrogen connected/bonded to an oxygen as opposed to bonding to the ...
Tue Oct 30, 2018 11:48 pm
Forum: Ionic & Covalent Bonds
Topic: Predicting which orbital an electron should be removed from to create 1+ ion
Replies: 2
Views: 150

### Predicting which orbital an electron should be removed from to create 1+ ion

In the 7th edition question 2A.13 part D asks to predict the type of orbital from which an electron will need to be removed to form the +1 ion of Cu. The answer is supposed to be the 4s orbital. Can someone explain why? I would've thought it would lose it from the 3d orbital?
Tue Oct 30, 2018 11:39 pm
Forum: Lewis Structures
Topic: Lewis Structure of BrF3 [ENDORSED]
Replies: 3
Views: 1026

### Lewis Structure of BrF3[ENDORSED]

I'm confused as to why the lewis structure of BrF3 permits 10 electrons surrounding Br (3 single bonds with each F for a total of 6 electrons) and then two pairs of lone pairs (4 electrons). I understand Bromine needs 7 valence electrons, but why are we allowed to add those extra lone pairs and brea...
Mon Oct 29, 2018 8:51 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 2
Views: 157

### Electron Affinity

On question 1F.11 (edition 7 of the textbook) the question asks for you to choose which element of a given pair has the higher electron affinity. How do you distinguish which element has the higher electron affinity if they are in the same group? Beryllium and magnesium (which are in the same group)...
Sat Oct 27, 2018 8:27 pm
Forum: Lewis Structures
Topic: Periodic Table Trends
Replies: 3
Views: 79

### Periodic Table Trends

Is there a difference between electron affinity and electronegativity? Or can these two terms be used interchangeably?
Sat Oct 27, 2018 8:19 pm
Forum: Lewis Structures
Topic: Polyatomic Ions
Replies: 3
Views: 102

### Polyatomic Ions

Would we be expected to memorize/know the charges of polyatomic ions/molecules for the test/midterm?
Thu Oct 25, 2018 9:43 am
Forum: Trends in The Periodic Table
Topic: Ionization Energies
Replies: 3
Views: 165

### Ionization Energies

When going across the periodic table ionization energy tends to increase. Nitrogen would have the tendency to gain electrons while Lithium would tend to lose an electron. What about elements in group 4 of the periodic table? Would they "rather" lose 4 electrons or gain 4 electrons?
Sun Oct 21, 2018 4:03 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Equation Confusion
Replies: 4
Views: 187

### Re: Heisenberg Equation Confusion

Hi, I believe Professor Lavelle mentioned that the 4pi results from a long derivation process for the Heisenberg Indeterminacy Equation but that we won't need to know it. As long as you know the equation you should be fine, and it may even be given on the test.
Sun Oct 21, 2018 3:52 pm
Forum: Quantum Numbers and The H-Atom
Replies: 1
Views: 1297

In my discussion section, we went over a problem asking us to calculate the wavelength of light emitted in the n=3 to n=2 transition in the hydrogen atom. When the solution was put up, the equation used to solve this was v= -R(1/n^2 - 1/n^2). I am confused as to why we put a negative in front of the...
Sun Oct 21, 2018 3:46 pm
Forum: Administrative Questions and Class Announcements
Topic: Test On Tuesday
Replies: 10
Views: 641

### Test On Tuesday

Hi, I was wondering if chapter 1F will be included on the test on Tuesday because in class, Dr. Lavelle mentioned the test would only include information taught up to Friday's lecture, but the outline on his website shows that we should also know 1F.
Sun Oct 14, 2018 1:56 pm
Forum: Properties of Light
Topic: Investigating Atoms: Topic 1A Problem 1A.15
Replies: 1
Views: 58

### Re: Investigating Atoms: Topic 1A Problem 1A.15

I used the second equation you listed that was shown in the book. This method was more efficient to me.
Sun Oct 14, 2018 1:54 pm
Forum: Administrative Questions and Class Announcements
Replies: 4
Views: 177

I believe we receive our homework back in our discussion sections and I'd assume we'd find out our test grades in the discussion section as well.
Sun Oct 14, 2018 1:48 pm
Forum: SI Units, Unit Conversions
Topic: Sig Figs
Replies: 8
Views: 581

### Re: Sig Figs

Whatever numbers are given in the problem allow you to determine sig figs. If you are multiplying or dividing numbers, you limit your sig figs to the smallest number of sig figs in the calculation. If it is addition or subtraction, you limit sig figs to the term in your calculation with the smallest...
Sun Oct 14, 2018 1:44 pm
Forum: Einstein Equation
Topic: Test #2
Replies: 4
Views: 237

### Re: Test #2

Test 2 will be given in our discussion section during week 4. If you go on the chem 14A class website, under test and exam schedules you can see a list of dates for all the upcoming tests.
Sat Oct 06, 2018 5:44 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Naming Compounds
Replies: 3
Views: 68

### Re: Naming Compounds

Fundamentals D touches on naming compounds, so that could be helpful to review prior to the test. However I think we will be given the formulas for the compounds on this first test.
Sat Oct 06, 2018 5:24 pm
Forum: SI Units, Unit Conversions
Topic: Fundamental E3
Replies: 6
Views: 376

### Re: Fundamental E3

So you know the left side is fixed with 9 atoms of gallium and you want the scale to be balanced. So find the mass of 9 gallium atoms by multiplying 9 by the molar mass (70 g/mol) which gives you 630 grams. Then to balance the other side you need to have 630 grams of astatine. So multiply the molar ...
Sat Oct 06, 2018 4:48 pm
Forum: Molarity, Solutions, Dilutions
Topic: Help with G5
Replies: 5
Views: 146

### Re: Help with G5

You start by solving for the molarity of Sodium Carbonate by first dividing the given mass of Na2CO3 (2.111g) by its molar mass which is 105.99 g/mol to get grams into moles. Then you take the number of moles you just calculated (.01992 mol) and divide that by the given volume of 0.25 L (I converted...