## Search found 85 matches

Mon Jan 18, 2021 3:29 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Ka and Kb
Replies: 3
Views: 15

### Re: Ka and Kb

another example is if you given the Ka value of NH4, then would the Kb value of Nh3 be able to be calculated from the give Ka value?
Mon Jan 18, 2021 3:24 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Ka and Kb
Replies: 3
Views: 15

### Ka and Kb

How to we calculate Ka given the Kb of a conjugate base
for example the Kb of Ch3NH2 is 3.6*10^-4. How would I get the Ka value of CH3NH3? would I just use the equation Ka*kb=Kw?
Mon Jan 18, 2021 3:08 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 6D.9
Replies: 3
Views: 19

### Re: 6D.9

For a) HCl is a strong acid so it disassociates completely. For b) Cl does not affect the pH when dissolved in water so CH3NH3+ is your acid. Although you are not given a Ka, table 6C.2 has the Kb for its conjugate base, methylamine. For c) the Ka is given in Table 6C.1 under acetic acid. For d) th...
Mon Jan 18, 2021 3:06 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 6D.5
Replies: 3
Views: 19

### Re: 6D.5

Hi! So for each of these, I started by using an ICE box and the given K values for each compound (in Table 6C.1 and 6C.2) to determine the x-value, which represents the equilibrium concentration of OH- or H3O+ for each equation. Using this value, you can then calculate pH and subsequently pOH or in...
Mon Jan 18, 2021 2:57 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 6D.9
Replies: 3
Views: 19

### 6D.9

Rank the following solutions in order of increasing pH: (a) 1.0 × 10−5 M
HCl(aq); (b) 0.20 M CH3NH3Cl(aq); (c) 0
.20 M CH3COOH(aq); (d) 0.20 M C6H5NH2(aq). Justify your ranking.

Im confused on how to even begin on this problem since we are not given the Ka values if anyone could help me with this
Sun Jan 17, 2021 2:49 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 6D.5
Replies: 3
Views: 19

### 6D.5

Calculate the pH, pOH, and percentage protonation of solute in each of the following aqueous solutions: (a) 0.057 MNH3(aq); (b) 0.162 M NH2OH(aq); (c) 0.35 M (CH3)3N(aq); (d) 0.0073 M codeine, given that the pKa of its conjugate acid is 8.21. Im confused on how to approach this problem becuase you d...
Sun Jan 17, 2021 2:23 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: HW problem 6D.3
Replies: 1
Views: 8

### HW problem 6D.3

(a) When the pH of 0.10 M HClO2(aq) was measured, it was found to be 1.2. What are the values of Ka and pKa of chlorous acid? (b) The pH of a 0.10 M propylamine, C3 H7NH2, aqueous solution was measured as 11.86. What are the values of Kb and pKbof propylamine? for these types of problems im confused...
Fri Jan 15, 2021 5:37 pm
Forum: Student Social/Study Group
Topic: Approaching Outlines
Replies: 13
Views: 34

### Re: Approaching Outlines

when I was in 14A i found it helpful to read the section first then do the homework problems right after doing that section. Also in reviewing for midterms and finals I would go over the practice problems again
Fri Jan 15, 2021 5:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Week 2 HW
Replies: 8
Views: 28

### Re: Week 2 HW

There are multiple ways to do this but one way is to calculate pOH from pH (14-pH=pOH) then use 10^-pOH = [OH-] to find OH-, hope this helps!
Fri Jan 15, 2021 1:55 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Hw promblem 6.3
Replies: 5
Views: 32

### Re: Hw promblem 6.3

Because the initial solution was supposed to be a concentration of 0.025 M, and it is a strong acid, the concentration of H+ would have been 0.025 M. You can find the desired pH by doing -log[0.025]. To find the actual pH, you can use the formula M1V1 = M2V2 to solve for M2. M1 would be 0.025M, V1 ...
Fri Jan 15, 2021 1:37 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Hw promblem 6.3
Replies: 5
Views: 32

### Hw promblem 6.3

A careless laboratory technician wants to prepare 200.0 mL of a 0.025 M HCl(aq) solution but uses a volumetric flask of volume 250.0 mL by mistake. (a) What would the pH of the desired solution have been? (b) What will be the actual pH of the solution as prepared? could someone explain to me how to ...
Thu Jan 14, 2021 1:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: sapling #4
Replies: 4
Views: 43

### sapling #4

At a certain temperature, the given reaction has an equilibrium constant of Kp=391 . PCl3(g)+Cl2(g)↽−−⇀PCl5(g) PCl5 is placed in a sealed container at an initial pressure of 0.0640 bar . What is the total pressure at equilibrium? Im having trouble getting the correct answer for this problem. I set u...
Fri Jan 08, 2021 2:02 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Textbook problem 5J.5
Replies: 2
Views: 18

### Re: Textbook problem 5J.5

Im not sure why that is so since in lecture today Lavelle went over if there is an increase in pressure there will be an increase in concentration. Given there are already more moles on the reactants side of this equation I would think there would be even more after the pressure increases. Maybe I c...
Fri Jan 08, 2021 2:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: after the ICE table
Replies: 3
Views: 28

### after the ICE table

I am pretty confident on making ICE table then using those to create the K equation but am unsure what to do after that of someone could explain that to me!
Fri Jan 08, 2021 1:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #3
Replies: 5
Views: 26

### Re: Sapling #3

I also have the same question! In addition to this I was wondering once we get the ice table and make the equation for K what do we do after?
Fri Jan 08, 2021 1:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: I.C.E.
Replies: 7
Views: 26

### Re: I.C.E.

It would be negative if you started with that species and it was changed through the reaction (basically if it was a reactant) then positive if its initial concentration was zero then it was added it (the products)
Thu Jan 07, 2021 1:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: concentration or partial pressure
Replies: 7
Views: 37

### concentration or partial pressure

At 500. K, the equilibrium constant for the reaction Cl2(g)+Br2(g)⇌2BrCl(g) is Kc=0.031. If the equilibrium composition is 0.495mol⋅L−1Cl2 and 0.145mol⋅L1BrCl, what is the equilibrium molar concentration of Br2? would you have to convert the initial values of Cl2 and BCl to pressure or could you kee...
Thu Jan 07, 2021 11:47 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW problem
Replies: 4
Views: 51

### HW problem

how do you approach this problem
Use the information in Table 5G.2 to determine the value of K at 300 K for the reaction
2BrCl(g+H2(g)⇌Br2(g)+2HCl(g)
.
Wed Jan 06, 2021 8:07 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: sapling #2
Replies: 8
Views: 44

### sapling #2

At a certain temperature, 0.920 mol SO3 is placed in a 5.00 L container.

2SO3(g)↽−−⇀2SO2(g)+O2(g)

At equilibrium, 0.170 mol O2 is present. Calculate Kc.

I am unsure how to approach this question if anyone could help me.
Sat Dec 12, 2020 4:04 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg example
Replies: 1
Views: 18

### Rydberg example

Light with a wavelength of 102.557 nm excites a hydrogen atom gas sample. Is the change in energy of a hydrogen atom positive or negative when it absorbs a photon? What is the principal quantum level of the state that the electron was excited to?

could someone explain to me how to solve this question
Sat Dec 12, 2020 3:51 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation
Replies: 4
Views: 25

### Rydberg equation

In the Rydberg equation( deltaE= (-hR/n1)-(-hR/n2)) which n goes where? does the start value of the n energy level =1 or does or change based on which level of n is higher?
Sat Dec 12, 2020 2:11 pm
Forum: Bronsted Acids & Bases
Topic: lewis vs bronsted
Replies: 8
Views: 35

### Re: lewis vs bronsted

A Lewis acid will accept an electron pair while a Lewis base will donate an electron pair. A Bronsted acid will donate a proton while a Bronsted base will accept a proton. I think of it as the Lewis acid will be accepting electrons (making it more negative) and a Bronsted acid will be donating a pr...
Sat Dec 12, 2020 10:52 am
Forum: Bronsted Acids & Bases
Topic: lewis vs bronsted
Replies: 8
Views: 35

### lewis vs bronsted

Could someone explain to me the difference between Lewis Acids/ bases and Bronsted acids/bases. Im confused on how they are able to correlate because they sound like they are the opposite of each other( lewis acid being an acceptor and bronsted acid being a donor)
Thu Dec 10, 2020 2:40 pm
Forum: Electronegativity
Topic: ionic bonds
Replies: 4
Views: 29

### ionic bonds

Which of these compounds has bonds that are primarily ionic? (a) BBr3;(b) BaBr2;(c) BeBr2 the answer in the textbook is BaBr2 and i was wondering why it is not BeBr2, the two seem to be the same distance away from Br on the periodic table so I assumed they would have almost the same difference in el...
Thu Dec 10, 2020 2:17 pm
Forum: Electronegativity
Topic: solubility
Replies: 2
Views: 18

### solubility

does more covalent or ionic character make a molecule more soluble?
Mon Dec 07, 2020 10:41 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: practice problem 1D 19
Replies: 2
Views: 18

### practice problem 1D 19

How many orbitals are present in the (a) 4p-subshell; (b) 3d-subshell; (c) 1s-subshell; (d) 4f-subshell of an atom?
would this answer to this be a) 3 b) 5 c)1 d)7
if not could someone explain to me how to find these values
Mon Dec 07, 2020 10:25 am
Forum: Quantum Numbers and The H-Atom
Topic: probabilty of finding e- in a location
Replies: 6
Views: 53

### probabilty of finding e- in a location

I am going over the Quantum section in the book and there are some formulas having to do with calculating the probability of finding a Hydrogen atom in a given region and was wondering if anyone knew if we needed to do this on the final? I dont remember having to do any problems like this on the fir...
Sun Dec 06, 2020 5:29 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: concept acid and bases
Replies: 3
Views: 15

### concept acid and bases

Im having a hard time grasping the concepts of acids and bases. SARe there any youtube videos anyone suggests visiting or websites that will help clear this up for me?
Sun Dec 06, 2020 5:28 pm
Forum: Student Social/Study Group
Topic: final study
Replies: 42
Views: 158

### final study

How does everyone plan on studying for the final/ are there any tips anyone could give?
Wed Dec 02, 2020 8:16 pm
Forum: Bronsted Acids & Bases
Topic: acids
Replies: 1
Views: 18

### acids

could someone explain to me why HCN is a weak acid? I thought it would be a strong acid because it gives away all of the hydrogens it has in a solution
Wed Dec 02, 2020 10:52 am
Forum: Molarity, Solutions, Dilutions
Topic: G19
Replies: 3
Views: 43

### G19

Would someone be able to explain how to do G19 part b to me? (b) A sample of 0.366 M HCl(aq)of volume 25.00 mL is drawn from a reagent bottle with a pipet. The sample is transferred to a flask of volume 125.00 mL and diluted to the mark with water. What is the molar concentration of the dilute hydro...
Wed Dec 02, 2020 10:31 am
Forum: Molarity, Solutions, Dilutions
Topic: dilution and molarity
Replies: 2
Views: 33

### dilution and molarity

How can you tell in a question whether you are supposed to use the equation M=mol/L or M(initial)*V(initial)=M(final)*V(final)
Im getting these two concepts confused when reviewing for the final
Sat Nov 28, 2020 3:07 pm
Forum: Sigma & Pi Bonds
Topic: rotation with pi bonds
Replies: 4
Views: 30

### rotation with pi bonds

Could someone explain to me why pi bonds are unable to rotate and sigma bonds are?
Sat Nov 28, 2020 3:01 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook 2E #25 part a
Replies: 3
Views: 24

### Re: Textbook 2E #25 part a

It would be polar regardless because of the tetrahedral shape of the molecule
Sat Nov 28, 2020 2:58 pm
Forum: Hybridization
Topic: When to invoke hybridization
Replies: 2
Views: 44

### Re: When to invoke hybridization

You have to draw out the lewis structure before you can determine the hybridization because you need to see if there are additional lone pairs attached to the central atom. In this specific example when you draw out the lewis structure you are to see that the central N atom has four regions of elect...
Sat Nov 28, 2020 2:47 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polar vs. nonpolar bonds/molecules
Replies: 8
Views: 66

### Re: Polar vs. nonpolar bonds/molecules

you have to keep into account the shape of the compound in questions. For example the lewis structure of a tetrahedral molecule with 4 atoms bonded that are not the same may look as if the dipole moments cancel out. However, when you take into account the tetrahedral molecular structure of the molec...
Sat Nov 28, 2020 2:39 pm
Forum: Hybridization
Topic: hybridization
Replies: 5
Views: 61

### hybridization

Does anyone know what d orbital hybridization looks like/ will we have to know what it looks like for the final exam?
Sat Nov 21, 2020 6:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 7 Sapling
Replies: 12
Views: 121

### Re: Week 7 Sapling

we have a sapling assignment for week 7 and 8 that isnt due till Sunday of midnight week 8!
Sat Nov 21, 2020 6:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: lone pair repulsion
Replies: 4
Views: 33

### Re: lone pair repulsion

Lone pairs are more repulsive than bonding electrons because they occupy more volume. Lone pairs are only attached to the one positively charged nucleus of their atoms, but the bonding electrons experience a stronger positive pull from the two nuclei of the atoms they connect. Because the lone pair...
Sat Nov 21, 2020 6:23 pm
Forum: Student Social/Study Group
Topic: Post Midterm Blues
Replies: 71
Views: 606

### Re: Post Midterm Blues

I felt this way about my first midterm too. It really helped to email my TA about it and talk it out! They really are looking to help you! Mine even offered to go over the midterm and let me ask any questions I wanted about it! Don't stress about it too much its just one exam!
Sat Nov 21, 2020 6:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear shape
Replies: 7
Views: 54

### Re: Linear shape

The lone pair on the N atom adds another region of electron density which in turns causes repulsion against the O2 atoms. This electron repulsion causes the O2 atoms to slightly 'bend' into an angular shape in order to ensure that the regions of electron density are as far as possible from eachother.
Sat Nov 21, 2020 6:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar or Nonpolar
Replies: 13
Views: 220

### Re: Polar or Nonpolar

Yes, if the VSEPR model indicates that the molecule's dipole moments cancel out, then it will be a nonpolar molecule ( and same vice versa). This can be shown clearly through cis-1,2-dichloroethene and trans-1,2-dichloroethene. These molecules have the same molecular formula, but the organization of...
Sat Nov 21, 2020 6:07 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: lone pair repulsion
Replies: 4
Views: 33

### lone pair repulsion

Would someone be able to explain why lone pairs on an atom are more repulsive than bonded electrons?
Sat Nov 21, 2020 6:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 4
Views: 96

### VSEPR

Will we have to know how to look at and analyze an electrostatic potential surface/ if so how do we do that?
Sun Nov 15, 2020 9:16 pm
Forum: Lewis Structures
Topic: Bonding with Atoms in the D State
Replies: 4
Views: 13

### Re: Bonding with Atoms in the D State

Yes! Make sure you check the formal charge of the atom once you have added the lone pair though because in some cases it can seem like you are able to add lone pairs but that might not be the most stable lewis structure for the molecule
Sun Nov 15, 2020 9:13 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Oxidation numbers
Replies: 3
Views: 17

### Oxidation numbers

For the upcoming midterm to what extent will we have to know oxidation numbers? I don't remember reading about them in the book or going over them in lecture.
Sun Nov 15, 2020 9:12 pm
Forum: Ionic & Covalent Bonds
Topic: Dissociation Energy & Unpaired e-
Replies: 2
Views: 34

### Re: Dissociation Energy & Unpaired e-

I think of the dissociation energy as the same concept of boiling point. The higher the dissociation energy the higher the bond strength. ( so a dissociation energy would be higher for a double or triple bonded atom rather than a single bonded atom). I hope this answered your question!
Sun Nov 15, 2020 9:10 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Plausible Formal Charges
Replies: 6
Views: 28

### Re: Plausible Formal Charges

Yes! when the formal charge is zero (or as close to zero as the structure will allow) is less reactive. This is due to the molecule having less of an intramolecular pull than molecules that have positive or negative formal charges or charges that do not cancel out.
Sun Nov 15, 2020 9:03 pm
Forum: Resonance Structures
Topic: resonance structures
Replies: 10
Views: 45

### Re: resonance structures

I beileive that it will be the resonance structure thats formal charge is closest to 0. (you can find formal charge of an atom by subtracting the total # of shared electrons/2 + # of lone electrons from the # of valence electrons the atom holds
Sun Nov 15, 2020 9:01 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: dipole moments
Replies: 10
Views: 54

### dipole moments

When drawing the arrow for net delta and delta positive in a molecule with a dipole moment which way does the arrow point? I believe in the textbook it said the arrow head should be pointed towards the delta positive atom, but I think in lectures lavelle was doing the opposite.
Thu Nov 12, 2020 2:12 pm
Forum: Formal Charge and Oxidation Numbers
Replies: 3
Views: 40

In one of the textbook problems it states that NO2- is a radical. I was wondering if someone could explain this to me because i thought the number of electrons the molecule had would be 18 (N->5 + o 6(2)+1=18)(making there no lone electrons in the lewis structure)
Fri Nov 06, 2020 1:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: valence electrons
Replies: 3
Views: 39

### valence electrons

How do you find the number of valence electrons for elements in the d block?
Thu Nov 05, 2020 6:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: sapling problem
Replies: 3
Views: 49

### sapling problem

On #4 of the sapling homework part of the problem is asking comparatively which bonds have ample bond character, would anyone be able to explain this to me?
Tue Nov 03, 2020 2:52 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electron con fig
Replies: 2
Views: 27

### Re: electron con fig

This happens only for the d orbitals and s orbitals, and not the p orbitals. As the energy of electrons increase, the space between these orbitals also decreases as seen in Dr. Lavelle's lectures. The d and s orbitals are so close that their energy levels seem to fluctuate. I think that the s and p...
Tue Nov 03, 2020 2:34 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: valence electrons
Replies: 7
Views: 87

### valence electrons

do we need to be able to find the number of valence electrons present in transition metals? if so how do we do this?
Tue Nov 03, 2020 2:12 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electron con fig
Replies: 2
Views: 27

### electron con fig

How is it decided when an electron is given to a higher energy level in electron configuration. for example in one of the practice problems in the book the electron con fig for Cl is 1s^2, 2s^2, 2p^2, 3s^2, 3p^5. However i thought that the 3s^2 would 'give' one electron to the 3p orbital so that it ...
Tue Nov 03, 2020 1:53 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: practice problems
Replies: 1
Views: 26

### practice problems

Would anyone be able to explain how they found a solution for 1E #7.
Im very confused on how to find if an element is in an excited state when given the electron configuration like it is given in the problem
Fri Oct 30, 2020 2:50 pm
Forum: Trends in The Periodic Table
Topic: Electron configuration
Replies: 2
Views: 30

### Re: Electron configuration

Hello! I think it changes because some of the subshells on the n=4 shell are lower in energy than some in the n=3 shell. For instance, if we consider the electron configuration of Zn, it follows such that the configuration is [Ar]4s^2,3d^10. I used the noble gas configuration for simplification, an...
Fri Oct 30, 2020 2:46 pm
Forum: Ionic & Covalent Bonds
Replies: 4
Views: 43

### Re: Van Der Waals radius

Jiwon_Chae_3J wrote:I think that knowing just the general concept should be sufficient.

ok, this is what I assumed since it was not gone over in lecture, thank you
Fri Oct 30, 2020 2:45 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 9
Views: 85

### Re: Electron Affinity

Wait correct me if I'm wrong but isn't affinity positive when energy is released from an atom gaining an electron (since the calculation for affinity is initial energy of the atom minus its final energy)? So Alexandra wouldn't electron affinities can be negative if energy is absorbed and positive w...
Fri Oct 30, 2020 2:42 pm
Forum: Balancing Chemical Reactions
Topic: Molar Mass
Replies: 23
Views: 187

### Re: Molar Mass

What I normally do is use the amount given on the periodic table, then focus on the sig figs given in the equation to make my final answer. So basically calculate with the full molar mass without rounding, then round based on sig figs at the end of the problem.
Fri Oct 30, 2020 1:54 pm
Forum: Trends in The Periodic Table
Topic: Electron configuration
Replies: 2
Views: 30

### Electron configuration

I noticed that sometimes when listing out the electron configuration of an atom the order of s,p,d,f changes. I think this has something to do with the building up principle, but i don't fully understand it. I was wondering how that was determined. If anyone could help me with examples that would be...
Fri Oct 30, 2020 1:51 pm
Forum: Ionic & Covalent Bonds
Replies: 4
Views: 43

I dont think that we went over this in lecture, but i read about the Van Der Waals radius in our book. I know that it involves noble gases but I'm confused on wether we will need to know any formulas regarding this or just know the general concept of it.
Sun Oct 25, 2020 12:27 pm
Forum: Properties of Electrons
Topic: Lyman and Balmer series
Replies: 6
Views: 64

### Re: Lyman and Balmer series

The Balmer series involves transitions starting or ending with n=2 and captures the visible light region of the hydrogen spectrum. On the other hand the Lyman series involves transitions beginning and ending with n=1 and captures the ultraviolet region. I think I remember Lavelle mentioning that we ...
Sun Oct 25, 2020 12:23 pm
Forum: Photoelectric Effect
Topic: unit conversion hw Q 1.3
Replies: 7
Views: 232

### Re: unit conversion hw Q 1.3

I had this question earlier in the week too, and I was confused since wavelengths are given in nm on the visible light spectrum. However, in equations you mostly will have to convert the wavelength you are given to meters since some constants you use in equations are in meters. You want to be able t...
Sun Oct 25, 2020 12:16 pm
Forum: General Science Questions
Topic: Rydberg Formula
Replies: 6
Views: 61

### Re: Rydberg Formula

When using the equation 1/λ = RZ^2(1/n1^2 - 1/n2^2) , you would plug in R=1.097 x 10^7/m. When using the equation v=R[1/n12-1/n22, you would plug in R= 3.29 x 10^15 Hz. I think there are different variations because the units are different. I found that this question was also asked on Chem Communit...
Tue Oct 20, 2020 2:40 pm
Forum: General Science Questions
Topic: Rydberg Formula
Replies: 6
Views: 61

### Re: Rydberg Formula

Hi, you're right! That's how I solved this equation. Using v=R[1/n 1 2 -1/n 2 2 ], I first input n 1 =5 with n 2 =6, and then I input n 1 =1 with n 2 =6. I initially kept getting this question wrong, but I realized it was because of a mistake with the Sig Figs that Sapling used... the only way it a...
Tue Oct 20, 2020 2:05 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation
Replies: 2
Views: 34

### Rydberg equation

Is the Rydberg equation 1/lamda =...... or is it lamda=.....
I am seeing both version on the homework versus the book
Mon Oct 19, 2020 5:18 pm
Forum: Properties of Electrons
Topic: sapling homework
Replies: 2
Views: 24

### Re: sapling homework

I converted cm to m giving me 2.51*10^-5 and I am still getting the incorrect answer
Mon Oct 19, 2020 5:10 pm
Forum: Properties of Electrons
Topic: sapling homework
Replies: 1
Views: 42

### sapling homework

Im having trouble on this problem How many photons with a wavelength of 723 nm are needed to melt 445 g of ice? The enthalpy of fusion of water can be found in this table. First i found the E(photon) using the equation E= h(c/lamda) which gave me 2.74754*10^-18 I then multiplied 333.6 (enthalpy of f...
Mon Oct 19, 2020 5:00 pm
Forum: Properties of Electrons
Topic: sapling homework
Replies: 2
Views: 24

### sapling homework

Having a lot of trouble on this problem A liquid is exposed to infrared radiation with a wavelength of 2.51×10−4 cm. Assume that all the radiation is absorbed and converted to heat. How many photons are required for the liquid to absorb 57.66 J of heat? I used the equation E=h(c/lamda) to find the e...
Mon Oct 19, 2020 4:12 pm
Forum: SI Units, Unit Conversions
Topic: SI units
Replies: 9
Views: 46

### SI units

I'm confused on whether we use nm or m when we have wavelength in an equation. I assumed it was nm since Lavelle gave us the wavelengths of the visible light spectrum in nm, however when I was working on the homework this week, my answer was incorrect because I used nm instead of converting it to m....
Sat Oct 17, 2020 10:53 am
Forum: Photoelectric Effect
Topic: photoelectric effect practice problem 1b15
Replies: 2
Views: 45

### Re: photoelectric effect practice problem 1b15

Hello! I'll break down what I did for each part. A) For part a I used the wavelength = h/p equation. For the top part, h is just Planck's constant and p is momentum so (mass x velocity, which is given). So, it would look something like this wavelength = (6.626x10^-34)/(3.6x10^6)*(9.11x10^-31), whic...
Fri Oct 16, 2020 3:11 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Bound energy versus free energy
Replies: 2
Views: 30

### Re: Bound energy versus free energy

Free electrons mean that they are not bound to an atom, while a bound electron is bound to the nucleus of the atom. Electrons that are bound to the nucleus are more stable at lower energy levels (their lowest energy level available). Keeping this in mind, when the electrons get excited, their energy...
Fri Oct 16, 2020 3:04 pm
Forum: Properties of Electrons
Topic: calculating the frequency of light
Replies: 4
Views: 41

### Re: calculating the frequency of light

In the equation used ( E=h(R/n^2) n is squared. Dr Lavelle simplified this part of the equation and put -1/16 and -1/4 instead of 1/4^2 and 1/2^2
Fri Oct 16, 2020 2:59 pm
Forum: Einstein Equation
Topic: wave vs. photons
Replies: 4
Views: 66

### wave vs. photons

In the lecture today Dr Lavelle mentioned that electrons show wave like properties. I was a bit confused because in previous lectures i thought he said electrons act as packets or particles. could someone help explain this to me?
Fri Oct 16, 2020 2:47 pm
Forum: Photoelectric Effect
Topic: When are electrons excited vs ejected
Replies: 16
Views: 129

### Re: When are electrons excited vs ejected

think of the equation E(photon)= Ek+ work force This means that the E(photon) must be greater than or equal to the kinetic energy of the electron plus the work force in order to eject the electron. If the energy of the photon is less than this then it will just excite the electron and lead in no eje...
Fri Oct 16, 2020 2:43 pm
Forum: Properties of Electrons
Topic: calculating the frequency of Light
Replies: 4
Views: 23

### Re: calculating the frequency of Light

The negative sign in front of the calculated J indicates that the electron lost or emitted that amount of energy, not absorbed it.
Fri Oct 16, 2020 2:41 pm
Forum: Photoelectric Effect
Topic: photoelectric effect practice problem 1b15
Replies: 2
Views: 45

### photoelectric effect practice problem 1b15

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6×10^3 km⋅s−1 (a) What is the wavelength of the ejected electron? (b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50×10^16 Hz. How much energy is required to...
Sat Oct 10, 2020 2:07 am
Forum: Administrative Questions and Class Announcements
Topic: Petition to Bring Music Back To Lectures [ENDORSED]
Replies: 34
Views: 538

### Re: Petition to Bring Music Back To Lectures[ENDORSED]

Yes,, NEED the music back
Fri Oct 09, 2020 1:26 pm
Forum: Empirical & Molecular Formulas
Topic: Sapling Hw Week 1 #10
Replies: 20
Views: 283

### Re: Sapling Hw Week 1 #10

Javier Perez M 2J wrote:Was this chemical reaction balanced already or did we have to balance it? The one provided in the question

The chemical equation is balanced already giving a ratio of 1:1:1:1
Thu Oct 08, 2020 4:19 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Moles textbook problem
Replies: 3
Views: 46

### Moles textbook problem

Has anyone completed E.9 from the text book and could explain how to work it out? I found the Epsom salt formula to be MgSO4 * 7H2O, but I'm not sure how to further work the problem to find how many atoms of oxygen are in 5.15g of Epsom salts.
Mon Oct 05, 2020 3:43 pm
Forum: Empirical & Molecular Formulas
Topic: Percent comp calculations
Replies: 5
Views: 79

### Percent comp calculations

How do you find percent comp by mass of each element when given only the molecular formula?
Mon Oct 05, 2020 12:38 pm
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 14
Views: 189

### Combustion

I got a little confused during the lecture when Lavelle began explaining how combustion, burning and oxidation are similar in their products. Would someone be able to explain this to me?
Mon Oct 05, 2020 12:25 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Accuracy vs Precision
Replies: 20
Views: 212

### Re: Accuracy vs Precision

The bullseye metaphor that Lavelle used in the pre recorded lecture helped clarify the concept, so if y'all are having a hard time grasping that I suggest watching that part again! Basically he explains that accuracy is like hitting the dart board close to the bullseye even if there are not consiste...