Search found 87 matches

by Brandon Valafar
Thu Feb 20, 2020 11:58 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Enthalpy
Replies: 6
Views: 22

Re: Enthalpy

State functions are independent values regardless of the pathway to get to the final value. The quantity only matters based on the final and initial values, and not the pathway to get there.
by Brandon Valafar
Thu Feb 20, 2020 11:50 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous
Replies: 16
Views: 36

Re: Spontaneous

If the delta G value is negative, then it is spontaneous toward the forward direction.
by Brandon Valafar
Thu Feb 20, 2020 11:48 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode
Replies: 5
Views: 15

Re: Anode

Since the electrons flow from the anode to the cathode, the cathode has a positive charge to attract the electrons, and the anode has to stay negative. The salt bridge lets this happen.
by Brandon Valafar
Thu Feb 20, 2020 11:44 am
Forum: Balancing Redox Reactions
Topic: Reduction vs. oxidation
Replies: 29
Views: 66

Re: Reduction vs. oxidation

Oxidation: loses electrons. Reduction: Gains electrons.
by Brandon Valafar
Wed Feb 19, 2020 6:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: midterm 3C
Replies: 4
Views: 24

Re: midterm 3C

Yes! NH4CL will dissociate into NH4+ and Cl- since NH4CL is inside a solution.
by Brandon Valafar
Wed Feb 19, 2020 6:54 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: converting T to kelvin
Replies: 20
Views: 46

Re: converting T to kelvin

Usually depends on the units in the given in the problem and what equation the problem entails in using. I usually always conver from C to K just to be safe unless it asks for it in units celsius.
by Brandon Valafar
Wed Feb 19, 2020 5:39 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Question 1 on Midterm
Replies: 6
Views: 21

Re: Question 1 on Midterm

Removing NO would make the reaction produce more reactants to balance out the reaction. Therefore NO2 partial pressure would decrease
by Brandon Valafar
Wed Feb 19, 2020 5:18 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 8
Views: 30

Re: Test 2

Test 2 starts the tuesday of week 9 and will cover the last page of the outline for thermodynamics and outline 5 of electrochemistry
by Brandon Valafar
Wed Feb 19, 2020 5:07 pm
Forum: Balancing Redox Reactions
Topic: Reduction vs. oxidation
Replies: 29
Views: 66

Re: Reduction vs. oxidation

Electrons are lost for oxidation and electrons are gained for reduction.
by Brandon Valafar
Wed Feb 19, 2020 2:37 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: rxn gibbs free energy
Replies: 5
Views: 23

Re: rxn gibbs free energy

Delta G has to be negative for a reaction to be spontaneous. Therefore, when delta G is negative, it means products are formed. When delta G is positive the reaction is not spontaneous and reactants are formed.
by Brandon Valafar
Wed Feb 19, 2020 2:32 pm
Forum: Balancing Redox Reactions
Topic: Balancing half reactions
Replies: 11
Views: 28

Re: Balancing half reactions

Yes! They do cancel out. We balance out the reactions so there is the same number of electrons lost on one side are gained on the other for them to cancel.
by Brandon Valafar
Wed Feb 19, 2020 2:23 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Delta H and Delta S
Replies: 3
Views: 24

Re: Delta H and Delta S

Delta S equals delta H over T which is temperature.
by Brandon Valafar
Wed Feb 19, 2020 2:21 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm Curve
Replies: 45
Views: 249

Re: Midterm Curve

I have been told that he does not curve the midterm, however, he does curve the class grading scale at the end of the quarter by just a little bit.
by Brandon Valafar
Wed Feb 19, 2020 2:20 pm
Forum: Balancing Redox Reactions
Topic: Test 2 [ENDORSED]
Replies: 12
Views: 71

Re: Test 2 [ENDORSED]

Test 2 was moved to week 9 and will cover the last part of the outline for thermodynamics and will cover electrochemistry as well.
by Brandon Valafar
Thu Jan 30, 2020 11:51 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Celcius and Kelvin
Replies: 11
Views: 29

Re: Celcius and Kelvin

I believe it son the equation sheet, and if not, it's pretty easy. K=273.15 +C
by Brandon Valafar
Thu Jan 30, 2020 11:49 am
Forum: Phase Changes & Related Calculations
Topic: Units
Replies: 16
Views: 52

Re: Units

K=273.15+C, so they are interchangeable.
by Brandon Valafar
Thu Jan 30, 2020 11:44 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Qv vs Qp
Replies: 7
Views: 23

Qv vs Qp

What is the difference between qv and qp?
by Brandon Valafar
Thu Jan 30, 2020 11:43 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: State Property
Replies: 6
Views: 25

Re: State Property

Yes it is a state property since it is the Final internal energy minus the initial internal energy.
by Brandon Valafar
Thu Jan 30, 2020 11:40 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Constant Pressure
Replies: 7
Views: 23

Re: Constant Pressure

This means that there is no change in pressure and no change in volume.
by Brandon Valafar
Wed Jan 29, 2020 2:43 pm
Forum: Lewis Acids & Bases
Topic: Lewis acid and bases
Replies: 5
Views: 26

Re: Lewis acid and bases

Lewis acid accepts electron pair, and lewis base donates electron pair.
by Brandon Valafar
Wed Jan 29, 2020 2:40 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 4A.1
Replies: 12
Views: 38

Re: 4A.1

closed systems can be impacted by their surroundings while isolated systems cannot.
by Brandon Valafar
Wed Jan 29, 2020 10:44 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Moles
Replies: 8
Views: 24

Re: Moles

You only count the gas atoms first. Then, moles go based off of coefficients, not the subscript.
by Brandon Valafar
Wed Jan 29, 2020 10:43 am
Forum: Calculating Work of Expansion
Topic: 4A and 4B Sections
Replies: 1
Views: 10

4A and 4B Sections

Has Lavelle done these yet? I feel like he skipped straight to 4C and 4D since I'm trying to do the earlier sections and am having trouble looking for notes on them.
by Brandon Valafar
Wed Jan 29, 2020 10:33 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Homework for Week 4
Replies: 2
Views: 22

Re: Homework for Week 4

Yeah those are correct. If you go on the syllabus it says to do those problems.
by Brandon Valafar
Wed Jan 29, 2020 10:32 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: temperature
Replies: 4
Views: 8

Re: temperature

It depends on the units. If the temperature is given in Celsius which it usually is you don't have to.
by Brandon Valafar
Mon Jan 20, 2020 12:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH sig figs
Replies: 5
Views: 38

Re: pH sig figs

From what I understand, you do the least amount of sig figs in the problem behind the decimal for pH. The link on Lavelle's website has a more in depth description though.
by Brandon Valafar
Mon Jan 20, 2020 10:52 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Endothermic vs Exothermic
Replies: 7
Views: 20

Endothermic vs Exothermic

How can I tell whether a reaction is exothermic or endothermic?
by Brandon Valafar
Sun Jan 12, 2020 2:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13 part c
Replies: 2
Views: 14

5I.13 part c

Why is cl2 more thermodynamically stable than f2 for part c of 5I.13?
by Brandon Valafar
Sun Jan 12, 2020 12:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5H.1
Replies: 2
Views: 13

5H.1

Hey I'm really confused on number 5H.1! Can someone please help or tell me if there are any rules I'm supposed to follow?
by Brandon Valafar
Sun Dec 08, 2019 12:01 am
Forum: Naming
Topic: Heme & Porphyrin
Replies: 2
Views: 44

Heme & Porphyrin

What is the difference between the heme complex and porphyrin and what do I need to know about each?
by Brandon Valafar
Sat Dec 07, 2019 6:01 pm
Forum: Naming
Topic: Oxalate Compound
Replies: 1
Views: 15

Oxalate Compound

What is the correct naming for the compound Na3[Co(C2O4)3] ?
by Brandon Valafar
Thu Dec 05, 2019 7:19 pm
Forum: Hybridization
Topic: Coefficient in front of orbitals
Replies: 1
Views: 26

Coefficient in front of orbitals

How do we know when to include a coefficient in front of the hybridized orbitals? And what coefficient do we put in what situations?
by Brandon Valafar
Thu Dec 05, 2019 7:19 pm
Forum: Hybridization
Topic: Coefficient in front of orbitals
Replies: 2
Views: 18

Coefficient in front of orbitals

How do we know when to include a coefficient in front of the hybridized orbitals? And what coefficient do we put in what situations?
by Brandon Valafar
Thu Dec 05, 2019 5:57 pm
Forum: Naming
Topic: 9C 1A
Replies: 3
Views: 27

Re: 9C 1A

Yes it does matter. Iron is one of the naming exceptions where it has a different name instead of just adding -ate to the end to become ironate.
by Brandon Valafar
Thu Dec 05, 2019 5:55 pm
Forum: Conjugate Acids & Bases
Topic: Hw problem 6A.7
Replies: 1
Views: 15

Re: Hw problem 6A.7

While I don't think it matters too much, I am not 100% sure. However, much of it is just common sense. Acids have their hydrogen in the front, while many molecules have their oxygen at the end.
by Brandon Valafar
Thu Dec 05, 2019 5:53 pm
Forum: Lewis Acids & Bases
Topic: Lewis Acid Base & Bronsted Acid And Base
Replies: 1
Views: 11

Re: Lewis Acid Base & Bronsted Acid And Base

Bronsted Acid's and Bases are based on protons while Lewis Acid's and Bases are based on electrons. Bronsted acids are proton donors and bronsted bases are proton acceptors while Lewis acids are electron lone pair acceptors and Lewis bases are electron lone pair donors.
by Brandon Valafar
Thu Dec 05, 2019 5:52 pm
Forum: Naming
Topic: Old vs New
Replies: 2
Views: 20

Re: Old vs New

I believe there isn't a difference and have seen Lavelle use the old ones in the lecture slides as well. I'm sure both naming methods will be accepted on the exam.
by Brandon Valafar
Thu Dec 05, 2019 5:50 pm
Forum: Amphoteric Compounds
Topic: 6A #11
Replies: 2
Views: 13

Re: 6A #11

HCO3- will be reacting with water and will pull and accept a proton from the water atom so the products/other side of the equilibrium will be H2CO3 and OH-.
by Brandon Valafar
Thu Dec 05, 2019 5:44 pm
Forum: Naming
Topic: Cyanido vs cyano
Replies: 5
Views: 36

Re: Cyanido vs cyano

They mean the same thing and just are different conventions. I'm going to use Lavelle's naming scheme since it is on his website.
by Brandon Valafar
Thu Dec 05, 2019 5:43 pm
Forum: Identifying Acidic & Basic Salts
Topic: Names of Acids and Bases
Replies: 3
Views: 53

Re: Names of Acids and Bases

I don't think it would hurt to know the basic ones however when I've asked TAs they said that we would not be tested on that and that it would be mostly formulas.
by Brandon Valafar
Thu Dec 05, 2019 5:41 pm
Forum: Lewis Acids & Bases
Topic: Hw problem 6A.13
Replies: 1
Views: 20

Re: Hw problem 6A.13

Lewis Acids are electron pair acceptors while Lewis Bases are electron pair donors. For 6A.13 (a), when you draw out the lewis structure for NH3, you realize that the N atom has an extra electron lone pair. This means that it will donate the lone pair through a bond, meaning that it is a Lewis base.
by Brandon Valafar
Thu Dec 05, 2019 5:38 pm
Forum: General Science Questions
Topic: Final
Replies: 2
Views: 49

Re: Final

The final is 8 questions (definitely with multiple parts each) and it is cumulative so it includes everything we've learned in this course.
by Brandon Valafar
Thu Dec 05, 2019 1:06 am
Forum: Lewis Acids & Bases
Topic: Salts as Acids and Bases
Replies: 2
Views: 19

Salts as Acids and Bases

For finding NH4Cl in an aqueous solution, why does Cl- not impact the pH and why do we leave it out of the equilibrium equation? Furthermore, when do we know to leave out atoms when dealing with salts in equilibrium equations?
by Brandon Valafar
Thu Dec 05, 2019 12:01 am
Forum: Lewis Acids & Bases
Topic: Problem 6C.17
Replies: 1
Views: 20

Re: Problem 6C.17

BrO- **** not BrO2
by Brandon Valafar
Wed Dec 04, 2019 11:58 pm
Forum: Lewis Acids & Bases
Topic: Problem 6C.17
Replies: 1
Views: 20

Problem 6C.17

I'm having a hard time how to identify which acids are stronger and which bases are stronger. Please help with this problem!!

Which is the stronger base, the hypobromite ion, BrO2, or
morphine, C17H19O3N? Justify your answer.

Thank you.
by Brandon Valafar
Wed Dec 04, 2019 5:25 pm
Forum: Ionic & Covalent Bonds
Topic: polarity of shapes
Replies: 4
Views: 42

Re: polarity of shapes

Square planar always has two lone pairs and has bond angles of 90 degrees.
by Brandon Valafar
Wed Dec 04, 2019 5:14 pm
Forum: Conjugate Acids & Bases
Topic: Conjugate Acids and Bases
Replies: 6
Views: 36

Re: Conjugate Acids and Bases

The best way to tell is to write out the equation and gauge which is an acid and base in the reactants and bases. Yes, the conjugate acids and bases will always be in the equation.
by Brandon Valafar
Wed Dec 04, 2019 4:12 pm
Forum: Naming
Topic: Naming Acids/ Bases
Replies: 4
Views: 25

Re: Naming Acids/ Bases

I believe we need to know some of the names of the common acids and bases but nothing too crazy.
by Brandon Valafar
Wed Dec 04, 2019 1:27 pm
Forum: Bronsted Acids & Bases
Topic: CaO
Replies: 10
Views: 59

Re: CaO

CaO is a Lewis base and because it is a metal oxide it will be a STRONG base that will be completely ionized (disassociated) in water leaving only Ca2+ and hydroxide ions.
by Brandon Valafar
Wed Dec 04, 2019 1:22 pm
Forum: Naming
Topic: Tips on Naming
Replies: 5
Views: 49

Re: Tips on Naming

There is a sheet on Lavelle's website called "Naming Coordination Compounds" which gives you a list of the common compounds/ligands in Chem 14A and their names. I put these on flashcards and that helped me a lot.
by Brandon Valafar
Wed Dec 04, 2019 1:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2 Average
Replies: 3
Views: 33

Re: Test 2 Average

My TA gave ours back after the lecture on Monday, but I think a lot of people are getting them back in discussions.
by Brandon Valafar
Tue Dec 03, 2019 12:30 am
Forum: Naming
Topic: Naming Compounds with Two Ligands
Replies: 3
Views: 28

Naming Compounds with Two Ligands

How do we know which ligand to put in the name first if there are two different ligands in the coordination compound? Thanks.
by Brandon Valafar
Tue Dec 03, 2019 12:20 am
Forum: Naming
Topic: Mono for Ligands with only one
Replies: 1
Views: 21

Mono for Ligands with only one

I've noticed that for some problems in the textbook that they do not add the "mono-" prefix when specifying how many of a ligand are in a compound. They simply just write the name of the ligand instead. Should we still write mono- when naming them regardless?
by Brandon Valafar
Tue Dec 03, 2019 12:19 am
Forum: Naming
Topic: Cobalt vs Cobaltate
Replies: 3
Views: 25

Cobalt vs Cobaltate

Hello, when should we use cobalt versus cobalt-ate in naming coordination compounds? Not just for cobalt but for transition metals in general, I seem to get confused on this topic.
by Brandon Valafar
Fri Nov 22, 2019 12:36 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: Hydrogen Bonding Atoms
Replies: 6
Views: 34

Hydrogen Bonding Atoms

For intermolecular hydrogen bonds, can hydrogen only bond to NOF atoms (with lone pairs) that are also attached/bonded to a hydrogen beforehand, or can they attach to any NOF atoms with lone pairs even if they aren't attached/bonded to a hydrogen beforehand within their molecule? TL;DR - Can hydroge...
by Brandon Valafar
Thu Nov 21, 2019 5:40 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: Hydrogen Bonding Rules
Replies: 6
Views: 51

Hydrogen Bonding Rules

Hello,

For hydrogen bonding, would a Nitrogen atom having two lone pairs be considered as TWO hydrogen bonding sites or one? In other words, is one atom a hydrogen bonding site or one lone pair?
by Brandon Valafar
Thu Nov 14, 2019 2:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle
Replies: 9
Views: 47

Re: Bond Angle

If there are lone pairs of electrons, those make the angle a little bit less than what it actually would be, due to repulsion.
by Brandon Valafar
Thu Nov 14, 2019 2:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: molecular shape vs. molecular geometry
Replies: 4
Views: 34

Re: molecular shape vs. molecular geometry

The geometry includes the lone pair electrons while the shape does not.
by Brandon Valafar
Thu Nov 14, 2019 2:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Will we need to know these VSEPR shapes as well?
Replies: 10
Views: 80

Re: Will we need to know these VSEPR shapes as well?

I believe we only need to know the ones he goes over in the lectures.
by Brandon Valafar
Thu Nov 14, 2019 2:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angles
Replies: 10
Views: 65

Re: bond angles

You could try to visualize the model of each shape, however I believe it's just one of those things you have to memorize. It will most likely be tested on so make sure you have it down.
by Brandon Valafar
Thu Nov 14, 2019 2:02 pm
Forum: Administrative Questions and Class Announcements
Topic: Date of Test 2
Replies: 3
Views: 28

Date of Test 2

When or what week is test 2 supposed to be? Is it supposed to be during week 8 or 9?
by Brandon Valafar
Thu Nov 14, 2019 1:53 pm
Forum: Administrative Questions and Class Announcements
Topic: Test #2
Replies: 4
Views: 28

Re: Test #2

Most likely we'll have to know the types of bonds and some background of lewis structures, but other than that I think it is mostly just VSPER model and forward.
by Brandon Valafar
Tue Nov 05, 2019 4:05 pm
Forum: Lewis Structures
Topic: Favorable Bonds
Replies: 5
Views: 36

Favorable Bonds

How many bonds would Nitrogen and Oxygen like to have?
by Brandon Valafar
Mon Nov 04, 2019 11:00 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability Periodic Trend
Replies: 5
Views: 46

Polarizability Periodic Trend

Is there any periodic trend for polarizability?
by Brandon Valafar
Mon Nov 04, 2019 10:59 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Power Periodic Trend
Replies: 4
Views: 32

Polarizing Power Periodic Trend

Is there any periodic trend for polarizing power?
by Brandon Valafar
Sun Nov 03, 2019 9:53 pm
Forum: Ionic & Covalent Bonds
Topic: Midterm
Replies: 2
Views: 24

Re: Midterm

Only up to 2D will be tested so any chemical bonds after that will not be on the midterm.
by Brandon Valafar
Sat Oct 26, 2019 4:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 5 Homework
Replies: 9
Views: 57

Re: Week 5 Homework

We've been covering chemical bonds recently, so I would say to do those. That will also help prepare you and help you understand the material as well and be on topic in TA discussion sessions.
by Brandon Valafar
Sat Oct 26, 2019 4:01 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 5
Views: 57

Re: Covalent Bonds

Non-metals are normally receiving or taking electrons from those atoms they are sharing with.
by Brandon Valafar
Sun Oct 20, 2019 5:37 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 1D.23
Replies: 1
Views: 23

1D.23

I am so confused on this problem? Can anyone help?
How many orbitals can have the following quantum numbers in an atom:(a)n=2,l=1; (b)n=4,l=2,ml=-2; (c)n=2;(d)n=3,l=2,ml=1 ?

Solutions manual says the answers are 3,1,4,1 but I have no idea how they got that.
by Brandon Valafar
Sun Oct 20, 2019 3:45 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: h bar formula [ENDORSED]
Replies: 4
Views: 48

h bar formula [ENDORSED]

In the textbook it says that h bar in the uncertainty equation is equal to h/2pi. However, in our notes it says that the hbar formula is h/4pi. Which are we supposed to use?
by Brandon Valafar
Sun Oct 20, 2019 12:27 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: The order in which subshells are filled
Replies: 3
Views: 29

Re: The order in which subshells are filled

If you're referring to the higher energy situation with 3d and 4s, then the rule is that if you can change from d9s2 to d10s1, or from d4s2 to d5s1, you must do so.
by Brandon Valafar
Sun Oct 20, 2019 12:22 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: configurations for p-orbital
Replies: 3
Views: 20

Re: configurations for p-orbital

I'm sure normally we will use the p3 form since it is much easier and standard. However if a question is asking you to specify I think that's when you use the xyz format.
by Brandon Valafar
Sun Oct 20, 2019 12:21 pm
Forum: Student Social/Study Group
Topic: Homework for Week 4
Replies: 4
Views: 43

Re: Homework for Week 4

Yeah we do 5 problems from quantum. We are still on this unit so it only makes sense to do problems from it.
by Brandon Valafar
Sat Oct 19, 2019 3:51 pm
Forum: Properties of Electrons
Topic: Angstrom Conversion
Replies: 12
Views: 104

Re: Angstrom Conversion

The angstrom conversion is 10e-10. The easiest way to convert for me is to convert from whatever unit it is to meters, and then from meters to angstroms so you don't get confused with the other conversion factors.
by Brandon Valafar
Sat Oct 19, 2019 3:47 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: determining types of orbitals (?)
Replies: 4
Views: 38

Re: determining types of orbitals (?)

You have to go based on the orbitals and their "blocks" on the periodic table. If you look up a periodic table for orbitals it should help on how to go about it.
by Brandon Valafar
Sat Oct 19, 2019 3:31 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: S and D orbitals
Replies: 1
Views: 29

S and D orbitals

When do we have to change the D orbital and S orbital because of the energy level?
by Brandon Valafar
Sun Oct 13, 2019 6:14 pm
Forum: Photoelectric Effect
Topic: confirmation.
Replies: 5
Views: 38

Re: confirmation.

Yes. A frequency that is less than the threshold value is not enough energy for the election to eject. It's true for all intensities.
by Brandon Valafar
Sun Oct 13, 2019 5:51 pm
Forum: Properties of Light
Topic: Question 1A.3 part c
Replies: 1
Views: 20

Question 1A.3 part c

I'm having a hard time understanding how " The extent of the change in the electrical field at a given point decreases" when the frequency decreases? How are these two proportional?
by Brandon Valafar
Sun Oct 13, 2019 5:18 pm
Forum: Significant Figures
Topic: How Many Sig Figs
Replies: 7
Views: 92

Re: How Many Sig Figs

My TA said that we shouldn't be too worried about sig figs since they haven't really been specified. However, it's a general rule of thumb to use the amount of sig figs that the value with the least amount of sig figs in a problem has.
by Brandon Valafar
Sun Oct 13, 2019 5:09 pm
Forum: SI Units, Unit Conversions
Topic: Unit conversion
Replies: 15
Views: 209

Re: Unit conversion

Angstroms are only used for meters. Angstroms also equal 10e-10. The easiest way for me to convert other units to angstroms is by first converting whatever units the value is to meters (lets say nanometers to meters) and then applying the unit conversion of 10e-10 to that.
by Brandon Valafar
Sun Oct 13, 2019 4:50 pm
Forum: Properties of Light
Topic: HW Question 1A.11
Replies: 2
Views: 40

Re: HW Question 1A.11

This is because the different series have different steps of going from higher to lower energy levels, as the comment above me said.
by Brandon Valafar
Wed Oct 02, 2019 12:25 pm
Forum: SI Units, Unit Conversions
Topic: mol, g.mol and g.mol-1
Replies: 12
Views: 157

Re: mol, g.mol and g.mol-1

I have not seen g.mol yet. However mol and g.mol-1 CANNOT be used interchangeably. They mean completely different things. Mol is the unit for moles. For example if a problem said 8.13 mol NaCl, it would mean that there are 8.13 Moles of NaCl. On the other hand, g.mol-1 means grams PER mole. The nega...
by Brandon Valafar
Wed Oct 02, 2019 12:22 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical and Molecular Formula Masses
Replies: 5
Views: 70

Re: Empirical and Molecular Formula Masses

Yes. The Empirical Formula mass can be equal to or less than the Molecular Formula mass, but not greater than.
by Brandon Valafar
Wed Oct 02, 2019 12:12 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.5 Concentration Calculation
Replies: 4
Views: 68

Re: G.5 Concentration Calculation

Once you find the molarity, I would first go about changing each of the units from milli-moles to moles. For example, this would make 2.15 mmol Na+ into 0.00215 mol Na+. Once you do that, for a, you have to find the volume needed for Na+. Since there are two Na+ atoms, you would have to divide the a...
by Brandon Valafar
Wed Oct 02, 2019 11:50 am
Forum: Significant Figures
Topic: How Many significant figures to use ?
Replies: 9
Views: 112

Re: How Many significant figures to use ?

The general rule is to use the least amount of sig figs. Based off the about of sig figs in the values a problem gives you, you make your answer in the least amount of sig figs given. For example: 1.256 + 0.023 = 1.3 , since in the second value, there are only 2 significant figures. You have to be c...
by Brandon Valafar
Sun Sep 29, 2019 1:47 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Metal Sulfides and Molar Mass
Replies: 3
Views: 62

Metal Sulfides and Molar Mass

E.15 The molar mass of the metal hydroxide M(OH) 2 is 74.10 g/mol.
. What is the molar mass of the sulfide of this metal?

What is a metal sulfide... and how am I supposed to go about solving this problem?

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