## Search found 77 matches

Wed Mar 13, 2019 12:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram
Replies: 3
Views: 160

### Re: Cell diagram

Usually a metal in the solid phase is what you want to look for
Tue Mar 12, 2019 5:14 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow or Fast Step
Replies: 3
Views: 164

### Re: Slow or Fast Step

Usually it will be explicitly stated, but if not you can tell which is the slow/fast step by looking at other information given.
For example, if a energy profile is given you want to pick the one with the lowest activation energy and that would be the fast step relative to the other.
Tue Mar 12, 2019 5:12 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: molecularity
Replies: 3
Views: 155

### Re: molecularity

You would give the molecularity of each step separately or if asked for the molecularity of the overall reaction you would go ahead and write the overall rxn from steps 1 and 2 and the write the molecularity of that overall rxn. You calculate molecularity by counting up how many moles are in the rea...
Sun Mar 10, 2019 10:11 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts Effect on Overall Rxn vs. Step of Rxn
Replies: 2
Views: 188

### Catalysts Effect on Overall Rxn vs. Step of Rxn

This has to do with homework problem 15.95 in the 6th edition For part of e of this question it says that a catalyst is speeding up the third reaction only and then asks what this does for the rate of the overall reaction. The answer is that there is no change and I was just a little confused to as ...
Wed Mar 06, 2019 7:41 pm
Forum: First Order Reactions
Topic: How to do 15.11 6th edition?
Replies: 4
Views: 178

### Re: How to do 15.11 6th edition?

The problem tells you that N2O5 decomposes by a first order reaction, so the rate law will have the form rate = k[A] where A is the reactant, N2O5, and the it is raised to the first power since it is a first order reaction. You are also given k = 5.2 x 10^-3. As mentioned before, you don't need to ...
Wed Mar 06, 2019 7:37 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Units
Replies: 6
Views: 235

### Re: Units

the m and n powers do not have units, they are just experimentally determined values
Wed Mar 06, 2019 7:33 pm
Forum: First Order Reactions
Topic: Half-Life
Replies: 2
Views: 125

### Re: Half-Life

The initial concentration just cancel each other out when the half life equation is being derived
Fri Mar 01, 2019 12:12 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Entropy based on shape of molecule
Replies: 3
Views: 146

### Re: Entropy based on shape of molecule

Trans has the higher entropy because it is able to occupy more possible positions.
Wed Feb 27, 2019 10:43 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Strength of Reducing Agents
Replies: 1
Views: 94

### Strength of Reducing Agents

I know you want to look at the most negative reduction potential in order to find which is the strongest reducing agent, but how do you know which equation to use if there are several that have that same metal in the back? 14.25 Arrange the following metals in order of increasing strength as reducin...
Mon Feb 25, 2019 10:05 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst equation with K and Q
Replies: 2
Views: 138

### Re: Nernst equation with K and Q

To see which way the reaction proceeds you would just compare Q and K with one another. If Q is less than K then it will proceed to the right and if Q is greater than K then it will proceed left.
Mon Feb 25, 2019 10:02 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2
Replies: 4
Views: 193

### Re: Test 2

Gibbs Free Energy will also be on the test! I believe Lavelle posted an announcement on his website on what would be on the test
Mon Feb 25, 2019 10:00 pm
Forum: Balancing Redox Reactions
Topic: balancing redox reaction
Replies: 2
Views: 145

### Re: balancing redox reaction

You're going to want to identify what was reduced and what was oxidized by looking at the different oxidation states. After that you want to balance the reactions and cancel!
Fri Feb 22, 2019 10:14 pm
Forum: Balancing Redox Reactions
Topic: difference between oxidation and reduction
Replies: 8
Views: 255

### Re: difference between oxidation and reduction

That's considered oxidation! The way I like to tbhink about it is if the charge was REDUCED then it was REDUCTION
Fri Feb 22, 2019 8:53 pm
Forum: Balancing Redox Reactions
Topic: Acidic Vs. Basic Redox Rxn
Replies: 3
Views: 157

### Re: Acidic Vs. Basic Redox Rxn

Acidic reactions give off electrons whereas basic reactions gain electrons
Thu Feb 21, 2019 9:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Explanation
Replies: 3
Views: 112

### Re: Explanation

I believe galvanic cells are just units that turn the chemical energy from redox reactions into electrical energy.
Thu Feb 21, 2019 4:25 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Reduction Potentials
Replies: 3
Views: 170

### Re: Reduction Potentials

Here's an article I found about reduction potentials!
https://socratic.org/questions/how-do-y ... -potential
Tue Feb 12, 2019 5:58 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Reasonable Assumptions
Replies: 2
Views: 141

### Re: Reasonable Assumptions

I don't have a list but I have two assumptions :
1. When a rxn is isothermal/reversible delta S Universe = 0
2. When a rxn is irreversible delta S Surroundings = 0
Tue Feb 12, 2019 5:56 pm
Forum: Student Social/Study Group
Topic: Equations Sheet
Replies: 4
Views: 444

### Re: Equations Sheet

Tue Feb 12, 2019 5:55 pm
Forum: Calculating Work of Expansion
Topic: moles and entropy
Replies: 3
Views: 174

### Re: moles and entropy

I guess what it comes down to is if you have enough information to calculate moles using pv=nrt, so if you're given all the information then you'd solve for n.
Sun Feb 10, 2019 6:18 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm #1 14B
Replies: 17
Views: 984

### Re: Midterm #1 14B

Ronald Thompson 1F wrote:Is there a solutions guide as well?

On the post Lyndon said that we shouldn't expect a solutions guide, so I'm assuming the only way to get answers is to go to the review session or get them from a buddy
Thu Feb 07, 2019 12:40 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Textbook Question
Replies: 1
Views: 119

### Re: Textbook Question

So for this problem you're gonna wanna use the ideal gas equations, Cp (constant pressure) is 5/2 of the gas constant (which is 8.314) and Cv (constant volume) 3/2 of the same gas constant. One you calculate the C for each scenario you'll plug it into equation nCdeltaT to solve for q which is the he...
Thu Feb 07, 2019 12:34 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: delta u
Replies: 2
Views: 118

### Re: delta u

I don't think so just because delta U is made up by the sum of heat and work done and work can still be done even if there's constant temperature.
Thu Feb 07, 2019 12:32 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 8
Views: 383

### Re: Midterm

I think Lavelle said something about what we learn up to Entropy will be the only thing we're tested on from Unit 4
Thu Jan 31, 2019 8:08 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Reaction Enthalpy
Replies: 3
Views: 153

### Re: Reaction Enthalpy

LedaKnowles2E wrote:What's delta U?

Delta U is the change in internal energy
Thu Jan 31, 2019 8:06 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Enthalpy
Replies: 6
Views: 166

### Re: Enthalpy

They're just given as positive values, but if you're forming the bond then you would write them as negative because it is an exothermic process
Wed Jan 30, 2019 6:31 pm
Forum: Phase Changes & Related Calculations
Topic: Week 4 Homework
Replies: 12
Views: 516

### Re: Week 4 Homework

Megan_Ervin_1F wrote:Why does this section talk about delta U? I don't recall learning about delta U in lecture...

I think we haven't learned about it yet. Lavelle in class today mentioned how he is teaching the material in a different order than the textbook goes.
Thu Jan 24, 2019 10:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Polyprotic acid question
Replies: 1
Views: 68

### Re: Polyprotic acid question

It mentioned in the textbook that if the second protonation is less than 1/1000 of the original one you can just solve for the first one and use that value of H3O/OH to calculate pH/pOH. It's because the second protonation would be so small there it would make no difference. H2SO4 is the exception i...
Wed Jan 23, 2019 6:01 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strong vs. weak acids and bases?
Replies: 5
Views: 372

### Re: Strong vs. weak acids and bases?

Here's a list of the strong acids and bases! You can assume everything else is weak. Hope this helps!
Wed Jan 23, 2019 4:38 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Ka and pH
Replies: 6
Views: 192

### Re: Ka and pH

I don't believe there's any equation that will relate the two. You would just have to use an ICE box, solve for the concentration of H3O/OH and then calculate pH/pOH
Thu Jan 17, 2019 5:44 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Strong acids and bases
Replies: 2
Views: 242

### Re: Strong acids and bases

Here's a picture of the strong acids and bases!
Thu Jan 17, 2019 5:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Tables [ENDORSED]
Replies: 11
Views: 514

### Re: ICE Tables[ENDORSED]

When using ICE tables, how do you know when its better to use the quadratic formula to find X or the 5% rule? If you're given a weak acid or base with an equilibrium constant less than 10^-3 you can assume that the x in the (number-x) is negligible and you can just get rid of that x. If it's not a ...
Wed Jan 16, 2019 6:17 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Approximation of x
Replies: 3
Views: 319

### Re: Approximation of x

Yes! Professor Lavelle mentioned that anytime the K value is less than 10^-3, the approximation of x in the reactant-x is negligible.
Wed Jan 09, 2019 5:20 pm
Forum: Ideal Gases
Topic: post assessment questions
Replies: 2
Views: 160

### Re: post assessment questions

To find the equilibrium constant you'll just use the equation concentration of the products/concentrations of the reactants, not pv=nrt.
Wed Jan 09, 2019 5:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Temperature and Equilibrium
Replies: 3
Views: 173

### Re: Temperature and Equilibrium

Usually you can tell by looking at whether or not the reaction is overall endothermic or exothermic. Usually with problems like that they should give you a delta H or just tell you.
Tue Jan 08, 2019 8:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW questions for discussion
Replies: 2
Views: 62

### Re: HW questions for discussion

Yes, I believe so
Fri Dec 07, 2018 1:40 pm
Forum: Naming
Replies: 1
Views: 106

I don't think that's been announced because I believe that's still being decided by Lavelle.
Your best bet for getting a solid answer on this might be emailing Lavelle (also if he does tell you this info plz share with the rest of chemistry community)
Fri Dec 07, 2018 1:38 pm
Forum: Ionic & Covalent Bonds
Topic: Inter and Intramolecular Forces
Replies: 3
Views: 288

### Re: Inter and Intramolecular Forces

Intramolecular forces are those that bind elements together, so for example covalent and ionic bonds.
Intermolecular forces are those that bind molecules or whole compounds together, so LDFs or H-Bonds.
Fri Dec 07, 2018 1:37 pm
Forum: *Shrodinger Equation
Topic: Shrodinger Equation meaning
Replies: 1
Views: 309

### Re: Shrodinger Equation meaning

Yes! All you need to know regarding shrodinger's equation is that it was what was used to calculate the electron densities in a cell and allowed for the "creation" of the orbitals!
Thu Nov 29, 2018 10:46 pm
Forum: Dipole Moments
Topic: Cis vs trans
Replies: 4
Views: 416

### Re: Cis vs trans

Yes, polarity does depend on whether the molecule is cis or trans.
I don't believe we will ever be given a molecule that could be either and asked about it's polarity if it's not specifically told which way it should be drawn.
Thu Nov 29, 2018 11:12 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Melting Points
Replies: 2
Views: 91

### Re: Melting Points

The first molecule possesses iodine atoms, which are substantially larger than the fluorine atoms found in the second molecule. With a larger atomic number, iodine has more electrons and a larger electron cloud. Iodine, therefore, has a larger polarizability value than fluorine and forces a group o...
Thu Nov 29, 2018 12:02 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Melting Points
Replies: 2
Views: 91

### Melting Points

Can someone explain why CHI4 has a higher melting point than CHF4. Thanks!
Tue Nov 20, 2018 11:17 am
Forum: SI Units, Unit Conversions
Topic: Significant 0’s [ENDORSED]
Replies: 8
Views: 567

### Re: Significant 0’s[ENDORSED]

this is a different way to remember significant figures
it's helpful if you get confused between decimal present and no decimal
Tue Nov 20, 2018 11:14 am
Forum: Hybridization
Topic: d Orbital
Replies: 6
Views: 170

### Re: d Orbital

I don't think we'll need to know how to draw the d orbital because it's complex compared to s and p
Tue Nov 20, 2018 11:13 am
Forum: Hybridization
Topic: Bond Angles
Replies: 4
Views: 169

### Re: Bond Angles

I believe so! You can also just memorize that a certain shape will have particular angles.
Thu Nov 15, 2018 11:40 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Do we not need to know oxidation numbers for this class?
Replies: 2
Views: 1747

### Re: Do we not need to know oxidation numbers for this class?

As of right now we haven't covered oxidation numbers! It may be in a different class of the chem series.
Thu Nov 15, 2018 11:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shapes
Replies: 3
Views: 141

### Re: Molecular Shapes

I think this is a good tool for classifying molecular shapes
Thu Nov 15, 2018 11:36 pm
Forum: Ionic & Covalent Bonds
Topic: Polar/non polar molecules
Replies: 5
Views: 230

### Re: Polar/non polar molecules

another way of looking at this is by looking at the types of bonds.
a molecule is most likely polar is has polar bonds, as in an atom with high EN is bonded to something with low EN.
a nonpolar molecule will compose of nonpolar bonds is two atoms with similar EN
Thu Nov 08, 2018 12:35 pm
Forum: Lewis Structures
Topic: Exceptions to the octet rule
Replies: 3
Views: 164

### Re: Exceptions to the octet rule

Group 13 elements are an exception to the octet rule because in order for them to get an octet they need to form 5 bonds which they're unable to do.
Then any element in the third row or lower is able to have an expanded octet because they have access to an empty d orbital
Wed Nov 07, 2018 6:51 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bond Exception?
Replies: 2
Views: 167

### Re: Covalent Bond Exception?

I don't think so just because non-metals and metals are usually charged as cations/anions, so these charges would make them ionic bonds. But! there may be exceptions that I've just never heard about.
Mon Nov 05, 2018 12:07 am
Forum: Octet Exceptions
Topic: EXPANDED OCTET
Replies: 5
Views: 238

### Re: EXPANDED OCTET

In order for them to have a complete octet they would need to create 5 bonds and that doesn't happen
Mon Nov 05, 2018 12:05 am
Forum: Empirical & Molecular Formulas
Topic: Energy Emission of Photons
Replies: 1
Views: 317

### Re: Energy Emission of Photons

The change in energy may be negative but the Energy given off can never be negative!
Fri Nov 02, 2018 5:02 pm
Forum: Ionic & Covalent Bonds
Topic: Electronegativity Difference
Replies: 6
Views: 275

### Re: Electronegativity Difference

I believe Lavelle said that we would be unable to make a definitive answer if it lies in between. We would need more information/experimentation to be able to tell which type of bond it is
Fri Nov 02, 2018 4:57 pm
Forum: Photoelectric Effect
Topic: Question on kinetic energy
Replies: 5
Views: 317

### Re: Question on kinetic energy

That equation is just for the kinetic energy of the ejected electron
You can't use that equation for the energy of a photon because mass is required and a photon has no measurable mass
hope this helped:)
Fri Nov 02, 2018 4:55 pm
Forum: Quantum Numbers and The H-Atom
Topic: Determining electrons
Replies: 3
Views: 362

### Re: Determining electrons

There are 2 electrons (up/down spin) per magnetic quantum. So for example n=2 l=1 Ml = -1,0,1 so for each of these three there are 2 electrons. So in this case it's a total of 6 electrons. For n=4 ... ms=-1/2 It is only 1 electron because they gave you all four quantum numbers and no 2 electrons in ...
Fri Nov 02, 2018 4:50 pm
Forum: Properties of Electrons
Topic: Test 2
Replies: 1
Views: 297

### Re: Test 2

By just multiplying by avogadro's number, you'll get how many electrons are in those 5 moles.
You just need to go one step further and multiple that number (the amount of electron in 5 mols) by the mass of an electron, so 9.109x10^-31 kg.

Hope this helped :)
Thu Nov 01, 2018 5:08 pm
Forum: Properties of Electrons
Topic: Electron Gaining/Losing energy
Replies: 5
Views: 383

### Re: Electron Gaining/Losing energy

When the atom is excited it is gaining energy, that is why it is able to jump to higher energy levels.

Hope this helped! :)
Thu Nov 01, 2018 5:03 pm
Forum: Student Social/Study Group
Topic: Studying
Replies: 7
Views: 415

### Re: Studying

I find doing the homework problems to be really helpful and then usually before the test I'll go over the homework again and redo the problem that I had initially struggled with. Also! sometime scrolling through chemistry community is really helpful just because reading how other people understand/e...
Thu Nov 01, 2018 2:57 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity of Gallium and Indium
Replies: 2
Views: 294

### Re: Electron Affinity of Gallium and Indium

Hi Julia!

There are some exceptions to the general trends in the periodic table; however, we aren't expected to know them unless they're explicitly stated.

Hope this helped :)
Thu Oct 25, 2018 7:41 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Ground state vs. excited state
Replies: 5
Views: 233

### Re: Ground state vs. excited state

when an electron is said to be in its excited state it has been "energized" and gone up to a particular shell, higher than the one it was originally at. Something that is in its ground state then it has either gone back down from being excited or there wasn't any source of energy and this ...
Thu Oct 25, 2018 7:39 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Quantum Numbers n, l, and m
Replies: 5
Views: 175

### Re: Quantum Numbers n, l, and m

Yes, that's how they could be described! and the highest possible subshell of a particular shell would be n-1!

Hope this helped!
Thu Oct 25, 2018 7:37 pm
Forum: *Shrodinger Equation
Topic: Help on how to find l, ml, and ms
Replies: 6
Views: 10232

### Re: Help on how to find l, ml, and ms

The maximum value of l is n-1.
Ml is -l to l
and Ms is either +1/2 or -1/2, that's not something we can figure out.

For example, if N=2 then..
l can be 1 or 0
Ml's -1,0,1

Hope this helped!
Sat Oct 20, 2018 7:07 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Confused on Problem 1.57 (regarding the Balmer Series)
Replies: 9
Views: 2206

### Re: Confused on Problem 1.57 (regarding the Balmer Series)

okay so I dug around a little and found a post that does a good job of explaining it, I'll link it below just in case anyone else is still confused :)
viewtopic.php?t=31402
Sat Oct 20, 2018 6:56 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Confused on Problem 1.57 (regarding the Balmer Series)
Replies: 9
Views: 2206

### Re: Confused on Problem 1.57 (regarding the Balmer Series)

Hello, I'm reviving an old post. However, I don't understand why you can figure out that n2=7 using the Balmer series. Can someone please explain? I'm also confused. I thought the balmer series started at 2, so wouldn't it be: 656.3 (n2), 486.1 (n3), 434.0 (n4), 410.2 (n5)... so wouldn't the next o...
Wed Oct 17, 2018 9:20 pm
Forum: SI Units, Unit Conversions
Topic: How does grading for discussion posts work?
Replies: 80
Views: 3792

### Re: How does grading for discussion posts work?

I'm having trouble even finding a way to post in this forum. Can someone tell me where/how I can post a question? I agree I am having trouble with that too but in the upper left side with the three lines next to "Quick Links" shows a tab that you can view "your posts" So you go ...
Wed Oct 17, 2018 9:16 pm
Forum: *Shrodinger Equation
Topic: Application
Replies: 1
Views: 81

### Re: Application

I believe Lavelle said in class that we will never need to calculate anything using this equation, but instead we learned it in order to give us background about how it was utilized when the different orbitals were discovered.
Wed Oct 17, 2018 9:13 pm
Forum: Photoelectric Effect
Topic: Work Function: Increase in Energy
Replies: 3
Views: 220

### Re: Work Function: Increase in Energy

This depends on whether or not one photon of light has enough energy to eject one electron. If this one photon has enough energy then by increasing the intensity of light you then increase the amount of photons, which then increases the amount of electrons that are ejected (1 photon per electron sor...
Wed Oct 17, 2018 9:09 pm
Forum: DeBroglie Equation
Topic: Energy of ejected electron from energy of light
Replies: 1
Views: 74

### Re: Energy of ejected electron from energy of light

When you're given the amount of energy of light used to eject an electron it's important to know if there's any excess energy in the form of kinetic energy given off. If there isn't any excess kinetic energy given off then we know the energy of the incoming light is equivalent to the energy of that ...
Wed Oct 10, 2018 10:47 pm
Forum: Properties of Light
Topic: Telling color by wavelength
Replies: 3
Views: 98

### Re: Telling color by wavelength

Yes, you can! Depending on the color it usually has a range of wavelength it falls under - I'll attach a photo I found online that shows the different colors and their corresponding wavelengths

I hope this helps!
Wed Oct 10, 2018 10:43 pm
Forum: SI Units, Unit Conversions
Topic: Ways to remember prefixes
Replies: 7
Views: 1825

### Re: Ways to remember prefixes

Okay this is kinda dumb, but hey whatever works, right? My (Mega) . 10^6 Kitten (Kilo) 10^3 Ben (Base) Null Doesn't (Deci) 10^-1 Count (Centi) 10^-2 Much (Milli) 10^-3 Money, (Micro) - you just have to remember here micro comes after milli 10^-6 No (Nano) 10^-9 Problem! (Pico) 10^-12 basically I thi...
Wed Oct 10, 2018 10:37 pm
Forum: SI Units, Unit Conversions
Topic: State of the molecules
Replies: 4
Views: 250

### Re: State of the molecules

I've also heard that we aren't expected to be able to identify different states of matter in the equation (like whether or not it's aqueous using solubility rules) so I don't think it'll be required of us!
Wed Oct 10, 2018 10:34 pm
Forum: Properties of Electrons
Topic: Problem 1.15 6th ed.
Replies: 1
Views: 63

### Re: Problem 1.15 6th ed.

So first things first you're going to want to convert to frequency using the c=wavelength*frequency equation. Then we will put these values in the Rydberg equation and for "n" you would use 1! I've also found this question worked out numerically and I'll go ahead and link that below. https...
Thu Oct 04, 2018 6:13 pm
Forum: Limiting Reactant Calculations
Topic: Competing Reactions
Replies: 2
Views: 346

### Re: Competing Reactions

I don't think we're ever going to have to identify that a competing reaction is going on. The main reason they mentioned that was to show why the actual yield is less than the theoretical yield (because the reactants can be used for something other than the main reaction going on).
Tue Oct 02, 2018 12:54 pm
Forum: Significant Figures
Topic: Mass Percent Composition
Replies: 4
Views: 462

### Mass Percent Composition

When it comes to finding the mass percent composition of a substance how many sig figs should we round to? Or is there a certain amount of decimal places we need to round to? Or does it not make a difference? I've noticed that in the textbook solution they'll usually do up to two decimal places, but...
Tue Oct 02, 2018 12:24 pm
Forum: Balancing Chemical Reactions
Topic: Net Number of Moles
Replies: 3
Views: 126

### Re: Net Number of Moles

I believe you'd just write out the complete chemical equation and the do total number of moles final - total number of moles initial to find out the net number of moles.
Also, when writing out the combustion remember that the other reactant is oxygen and the products are CO2 and H20
Hope this helped!
Tue Oct 02, 2018 11:48 am
Forum: Molarity, Solutions, Dilutions
Topic: Pre-Module Assessment Q23 and Q25
Replies: 2
Views: 428

### Re: Pre-Module Assessment Q23 and Q25

Hello! Okay, to start off #23 is a dilution problem, so we know we want to get it into a M1V1=M2V2 equation. First we're going to solve for M1 andyou're going to want to convert the grams of KMnO4 into mols (so divide by the molar mass). 5.00 g KMnO4/58.04 g/mol = .0316 mol KMnO4 Then you're going t...
Sun Sep 30, 2018 9:25 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Happy Lavelle [ENDORSED]
Replies: 5
Views: 772

### Re: Happy Lavelle[ENDORSED]

Hello, I just made my account and I cannot find where to post my questions? Please help. Hi Sarah! So you go to the main page and scroll down until you see the section labeled "Chem 14a", then go ahead and click on the subject matter that pertains to your question. Then you'll get to a pa...
Sun Sep 30, 2018 9:10 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molar Mass of Sulfide
Replies: 2
Views: 209

### Re: Molar Mass of Sulfide

I found the answer to this question on an earlier post and I believe they did a good job of explaining it! I'll go ahead and link it below :)

viewtopic.php?t=5565