Search found 89 matches

by Sally Qiu 2E
Sun Feb 23, 2020 11:50 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: porous disc
Replies: 5
Views: 10

Re: porous disc

the porous disc has the same effect as a salt bridge as it keeps the charges balances
by Sally Qiu 2E
Wed Feb 19, 2020 6:55 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: converting T to kelvin
Replies: 21
Views: 57

Re: converting T to kelvin

it's okay to leave the temperature in celsius if you're just finding the change-- it shouldnt make a difference mathematically
by Sally Qiu 2E
Tue Feb 18, 2020 1:52 pm
Forum: Balancing Redox Reactions
Topic: Balancing and Adding together Half-Rxns
Replies: 6
Views: 16

Re: Balancing and Adding together Half-Rxns

the charge of electrons must be maintained; same reasoning as to why we balance equations in general
by Sally Qiu 2E
Tue Feb 18, 2020 1:51 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: ∆G = ∆Gº + RT lnQ
Replies: 12
Views: 55

Re: ∆G = ∆Gº + RT lnQ

delta G is the gibbs free energy under standard conditions
by Sally Qiu 2E
Tue Feb 18, 2020 1:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Van't Hoff Equation
Replies: 4
Views: 13

Re: Van't Hoff Equation

van't hoff equation is used to find the K value for different temperatures
by Sally Qiu 2E
Tue Feb 18, 2020 1:49 pm
Forum: Van't Hoff Equation
Topic: Constant delta H
Replies: 4
Views: 16

Re: Constant delta H

we are assuming the difference between the final H and initial H to remain constant, and that the temperature change isn't significant enough to affect that
by Sally Qiu 2E
Fri Feb 14, 2020 5:17 pm
Forum: Calculating Work of Expansion
Topic: Determining Expansion Work
Replies: 4
Views: 18

Re: Determining Expansion Work

if there was a change in the number of moles, the system had done expansion work (if the volume can change)
by Sally Qiu 2E
Fri Feb 14, 2020 5:13 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free energy concept
Replies: 16
Views: 42

Re: Gibbs Free energy concept

gibbs free energy is basically the energy that is available to do work, hence "free" energy.
by Sally Qiu 2E
Fri Feb 14, 2020 5:12 pm
Forum: Phase Changes & Related Calculations
Topic: Expansion Work
Replies: 6
Views: 26

Re: Expansion Work

expansion means there was an increase in volume
by Sally Qiu 2E
Fri Feb 14, 2020 5:11 pm
Forum: Phase Changes & Related Calculations
Topic: Delta H Fusion
Replies: 8
Views: 43

Re: Delta H Fusion

the temperature doesn't change during a phase change. you can keep adding heat but the temperature doesn't change. you would need to calculate the energy needed to raise the temperature to the melting point, then find the amount of energy needed to actually melt the substance
by Sally Qiu 2E
Fri Feb 14, 2020 5:09 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal Reversible
Replies: 6
Views: 26

Re: Isothermal Reversible

i think isothermal always means reversible but not necessarily the other way around
by Sally Qiu 2E
Mon Feb 10, 2020 6:00 pm
Forum: Administrative Questions and Class Announcements
Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
Replies: 66
Views: 2260

Re: Pizza Rolls REVIEW Session DOWNLOAD HERE

can someone explain the lex luthor problem to me? it's number 5. i think for part a, i need to use the 2 entropy equations as well as the equipartition thing. and i'm not sure about b...
by Sally Qiu 2E
Sun Feb 09, 2020 9:40 am
Forum: Administrative Questions and Class Announcements
Topic: memorizing things?
Replies: 13
Views: 54

memorizing things?

are there any specific values we need to memorize for this midterm? like heat capacities and whatnot?
by Sally Qiu 2E
Sat Feb 08, 2020 1:28 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy
Replies: 3
Views: 11

Re: Entropy

is it not a state function? if i recall correctly, entropy is in fact a state function because it does not depend on the path followed by the system--just the final and initial state. however, the entropy does depend on the size or amount of moles. entropy=q/T, and q itself is extensive
by Sally Qiu 2E
Thu Feb 06, 2020 7:55 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: 3rd Law
Replies: 4
Views: 12

Re: 3rd Law

as the temperature approaches 0 K, the change in entropy would approach 0. with the example of the perfect crystal, there is no inherent disorder and it must be at 0 K or else there will be some motion within the crystal
by Sally Qiu 2E
Wed Feb 05, 2020 3:00 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: heat given off by rxn = - heat absorbed by solution
Replies: 6
Views: 22

Re: heat given off by rxn = - heat absorbed by solution

the heat given off by the rxn would be absorbed by the surroundings. i'm not sure if you need to know specifically which side the negative is on, as long as one is negative?
by Sally Qiu 2E
Tue Feb 04, 2020 6:14 pm
Forum: Calculating Work of Expansion
Topic: second equation
Replies: 8
Views: 26

Re: second equation

if you solve the integral you would get ln( V2/V1).
by Sally Qiu 2E
Mon Feb 03, 2020 7:56 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed Systems
Replies: 11
Views: 36

Re: Closed Systems

in a closed system, you can change the energy by doing work/having work done on the system or by changing the temperature
by Sally Qiu 2E
Sat Feb 01, 2020 9:51 am
Forum: Phase Changes & Related Calculations
Topic: Enthalpy vs Change in Internal Energy
Replies: 4
Views: 13

Re: Enthalpy vs Change in Internal Energy

internal energy includes heat and work. sometimes change in internal energy is equal to change in enthalpy, and this happens when you are at constant pressure and volume.
by Sally Qiu 2E
Sat Feb 01, 2020 9:48 am
Forum: Phase Changes & Related Calculations
Topic: Internal Energy, U
Replies: 6
Views: 27

Re: Internal Energy, U

it's equal if you are at constant pressure and volume.
by Sally Qiu 2E
Thu Jan 30, 2020 7:06 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Changing the energies of systems
Replies: 2
Views: 11

Re: Changing the energies of systems

in an open system, you can add or remove products/reactants. in a closed system, you can change the pressure by compression/expansion (work) or changing the temperature. you cannot change the energy of an isolated system.
by Sally Qiu 2E
Thu Jan 30, 2020 6:25 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed and Isolated
Replies: 5
Views: 12

Re: Closed and Isolated

i think there are few, if any, isolated systems in the world. maybe there's such minuscule amount of change that it's negligible?
by Sally Qiu 2E
Thu Jan 30, 2020 6:22 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpies
Replies: 4
Views: 19

Re: Bond enthalpies

it depends on whether or not the value of bonds formed is greater than that of bonds broken.
by Sally Qiu 2E
Sun Jan 26, 2020 12:03 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 7
Views: 14

Re: Hess's Law

hess's law is basically stating that because enthalpy is a state function, enthalpy is additive. you can simply add the enthalpies of reactions; regardless of how many steps a reaction has, the total enthalpy change is just the sum of all changes
by Sally Qiu 2E
Sun Jan 26, 2020 12:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: bond enthalpies
Replies: 2
Views: 9

Re: bond enthalpies

you would have to draw out the lewis structures and see which bonds were broken and formed in the products.
by Sally Qiu 2E
Wed Jan 22, 2020 11:16 pm
Forum: Administrative Questions and Class Announcements
Topic: Best Way To Study?
Replies: 13
Views: 59

Re: Best Way To Study?

the examples done in lectures are the most accurate representations of what show up in exams. Make sure you thoroughly understand the concepts behind each example so that you are able to recognize what steps to take when you encounter a similar problem on an exam.
by Sally Qiu 2E
Tue Jan 21, 2020 11:19 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H20 in the ICE table
Replies: 26
Views: 91

Re: H20 in the ICE table

leave out pure liquids and solids
by Sally Qiu 2E
Tue Jan 21, 2020 8:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to Use Q
Replies: 3
Views: 27

Re: When to Use Q

wait so for this problem we had to make sure which direction it went in?
by Sally Qiu 2E
Tue Jan 21, 2020 8:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Test One Content
Replies: 6
Views: 60

Re: Test One Content

homework problems are good practice, i wouldn't bank on them being on the test though. and yes, the test covers outline 1 and 2.
by Sally Qiu 2E
Tue Jan 21, 2020 7:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Grading of Tests
Replies: 18
Views: 92

Re: Grading of Tests

you usually get partial credit yeah
by Sally Qiu 2E
Tue Jan 21, 2020 7:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ice box approximation
Replies: 9
Views: 46

Re: ice box approximation

if the K value is less than 10^-3, then you can assume x is very small relative to the initial concentration. this makes sense when you think about the formula for K (the concentration of reactants is much greater than that of products). if this is the case, you can disregard the x (that is subtract...
by Sally Qiu 2E
Sun Jan 19, 2020 11:39 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Box
Replies: 4
Views: 8

Re: ICE Box

it's ignored if it's in a liquid state. as a solvent, it's in large excess, the concentration isn't really gonna change so it's not included in the K equation
by Sally Qiu 2E
Thu Jan 16, 2020 11:28 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs Kp
Replies: 5
Views: 12

Re: Kc vs Kp

usually Kc is used, but i believe the problem would specify which one to use. you can also tell by the information given by a problem
by Sally Qiu 2E
Thu Jan 16, 2020 11:27 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Quadratic
Replies: 10
Views: 36

Re: Quadratic

i don't think you would get 2 positive answers often, but just in case i'd plug the values back into the ICE table to see which value is more reasonable
by Sally Qiu 2E
Thu Jan 16, 2020 11:25 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Factos effecting Equilibrium
Replies: 6
Views: 10

Re: Factos effecting Equilibrium

change in concentration, pressure (from volume), and temperature. temperature is the only one that affects the K value
by Sally Qiu 2E
Wed Jan 15, 2020 4:08 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient
Replies: 11
Views: 34

Re: Reaction Quotient

if the reaction is not at equilibrium, or if you aren't sure, then you are calculating the reaction quotient. It is the same equation as K. it can be used, when compared to K, to determine which way the reaction is proceeding
by Sally Qiu 2E
Wed Jan 15, 2020 4:07 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: How to make ICE box
Replies: 15
Views: 89

Re: How to make ICE box

The change would be x if you aren't given the equilibrium concentrations. Unless there are coefficients, then it would be corresponding coefficient times x.
by Sally Qiu 2E
Fri Jan 10, 2020 4:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: using Kp vs Kc
Replies: 13
Views: 35

Re: using Kp vs Kc

you would use Kp if you are given the partial pressures.
by Sally Qiu 2E
Fri Jan 10, 2020 4:07 pm
Forum: Student Social/Study Group
Topic: Test 1 14B Topics
Replies: 4
Views: 46

Re: Test 1 14B Topics

definitely study outline 1, but i'm not sure if some of outline 2 will be covered
by Sally Qiu 2E
Fri Jan 10, 2020 4:06 pm
Forum: Ideal Gases
Topic: Chatelier’s Principle
Replies: 8
Views: 41

Re: Chatelier’s Principle

basically the reaction will "adjust" to keep K constant. if you add more products and throw off the equilibrium, the reaction will proceed to the left to form more reactants. Regarding the change in pressure, the reaction will proceed towards the side with less moles of gas; however, it is...
by Sally Qiu 2E
Fri Jan 10, 2020 4:02 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: K vs Q
Replies: 9
Views: 51

Re: K vs Q

the equation to calculate K and Q is the concentration of products over concentration of reactants. If Q is less than K, that means that there must be more reactants compared to the concentrations at equilibrium. Therefore, the reaction will shift to the right to produce more products. the same logi...
by Sally Qiu 2E
Fri Jan 10, 2020 3:57 pm
Forum: Ideal Gases
Topic: R in PV=nRT
Replies: 34
Views: 366

Re: R in PV=nRT

R is a gas constant and the numerical value depends on the units being used to measure the gas
by Sally Qiu 2E
Sun Dec 01, 2019 10:24 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Do strong acids dissociate completely in water?
Replies: 7
Views: 42

Re: Do strong acids dissociate completely in water?

yes, strong acids dissociate completely in water. whether or not an acid (or a base) ionizes completely in water depends on the polarity. when there is a significant electronegativity difference, there is less electron density associated with hydrogen and it is easier to ionize
by Sally Qiu 2E
Sun Dec 01, 2019 10:18 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Pka vs Ka
Replies: 10
Views: 79

Re: Pka vs Ka

ka is the acid dissociation constant, and pka is the -log of Ka
by Sally Qiu 2E
Sat Nov 30, 2019 10:07 am
Forum: Lewis Acids & Bases
Topic: Proton acceptor and proton donor?
Replies: 33
Views: 140

Re: Proton acceptor and proton donor?

bases are proton acceptors, so they gain a H+. acids are proton donors, so they lose a H+
by Sally Qiu 2E
Sat Nov 30, 2019 10:06 am
Forum: Amphoteric Compounds
Topic: Examples of amphoteric compounds
Replies: 5
Views: 27

Re: Examples of amphoteric compounds

i think Lavelle said to memorize the diagonal line of elements on the periodic table.
by Sally Qiu 2E
Sat Nov 30, 2019 10:05 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Weak Acids and Bases
Replies: 5
Views: 244

Re: Weak Acids and Bases

you'll know based on the kb value. i believe there are strong acids and bases you can memorize, and anything else not on that list is a weak acid/base
by Sally Qiu 2E
Sat Nov 23, 2019 9:59 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 3
Views: 28

Re: Polydentate

the best way to be sure would be to draw the structure and see how many bonds the ligand can form. if there can be multiple bonds formed, then the ligand is polydentate
by Sally Qiu 2E
Sat Nov 23, 2019 9:57 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxidation State
Replies: 4
Views: 21

Re: Oxidation State

for monoatomic ions, the oxidation state is the same as the charge, so just look at the periodic table.
by Sally Qiu 2E
Sat Nov 23, 2019 9:54 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordinate covalent bonds
Replies: 2
Views: 16

Re: Coordinate covalent bonds

in a coordinate covalent bond, the electrons involved in bonding comes from one of the atoms, while in normal covalent bonds both atoms will contribute electrons
by Sally Qiu 2E
Sat Nov 23, 2019 9:53 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted Acids vs Lewis acids
Replies: 4
Views: 25

Re: Bronsted Acids vs Lewis acids

a bronsted acid describes acids as proton donors, as in they lose an H+. the lewis definition of an acid is that they are electron acceptors, so they gain electrons.
by Sally Qiu 2E
Sat Nov 23, 2019 9:51 pm
Forum: Sigma & Pi Bonds
Topic: How to Find Sigma Bonds and Pi Bonds
Replies: 15
Views: 104

Re: How to Find Sigma Bonds and Pi Bonds

draw the lewis structure. a single bond is one sigma bond, a double bond is one sigma bond and one pi bond, and a triple bond is one sigma bond and two pi bonds.
by Sally Qiu 2E
Sat Nov 16, 2019 4:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent or Angular
Replies: 13
Views: 97

Re: Bent or Angular

i don't believe there's a difference? the textbook may say angular but lavelle referred to it as "bent"
by Sally Qiu 2E
Sat Nov 16, 2019 4:22 pm
Forum: Bond Lengths & Energies
Topic: Dissociation Energy
Replies: 9
Views: 35

Re: Dissociation Energy

dissociation energy is the energy required to break a bond, and since breaking bonds requires energy, the dissociation energy will be positive
by Sally Qiu 2E
Sat Nov 16, 2019 4:17 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: Boiling Points
Replies: 9
Views: 55

Re: Boiling Points

the stronger the intermolecular force, the higher the boiling point. for example, the boiling point of water is 100 C, while the boiling point of methane (CH4) is like -260 C. water molecules are polar, which means there will be dipole-dipole forces as well as LDF (LDF are present in all molecules i...
by Sally Qiu 2E
Sat Nov 16, 2019 3:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polar vs nonpolar
Replies: 6
Views: 34

Re: polar vs nonpolar

i prefer to draw the lewis structure; then you can see if the structure is symmetrical or not.
by Sally Qiu 2E
Fri Nov 08, 2019 7:29 pm
Forum: Dipole Moments
Topic: Dipole Moments
Replies: 5
Views: 55

Re: Dipole Moments

dipole moments are the result of differences in electronegativity, and the atoms share electrons unequally. this creates a partial charge of +/-.
by Sally Qiu 2E
Fri Nov 08, 2019 7:27 pm
Forum: Electronegativity
Topic: memorizing tables
Replies: 9
Views: 41

Re: memorizing tables

i don't think you need to memorize the actual numbers, but you can at least have a general, relative estimate of the values maybe
by Sally Qiu 2E
Fri Nov 08, 2019 7:26 pm
Forum: Dipole Moments
Topic: Dipole - Dipole vs. Hydrogen Bonding
Replies: 7
Views: 280

Re: Dipole - Dipole vs. Hydrogen Bonding

h bonding is an intermolecular force, so attraction between molecules. it is the stronger than dipole-dipole, which is also an intermolecular force. h bonding is weaker than covalent or ionic bonds though.
by Sally Qiu 2E
Fri Nov 08, 2019 7:22 pm
Forum: Lewis Structures
Topic: Formal Charges
Replies: 15
Views: 65

Re: Formal Charges

the charge isn't necessarily for the central atom. the most electronegative atom should have the negative charge
by Sally Qiu 2E
Sun Nov 03, 2019 4:23 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: polarizing power
Replies: 3
Views: 16

Re: polarizing power

ions with high polarizing power cause large distortions in another atom's electron cloud. to determine polarizing power, you'll have to take into consideration the atomic radius and charge; small cations that are highly charged have the most polarizing power. due to the small size, the nucleus of th...
by Sally Qiu 2E
Sun Nov 03, 2019 4:13 pm
Forum: Bond Lengths & Energies
Topic: Resonance bond length
Replies: 4
Views: 28

Re: Resonance bond length

kind of yeah? i see it more as resonance describing the delocalization of electrons. but yes the bond length is the average
by Sally Qiu 2E
Sun Nov 03, 2019 2:49 pm
Forum: Octet Exceptions
Topic: What are radicals
Replies: 7
Views: 39

Re: What are radicals

radicals are compounds that have a lone electron. this makes them very reactive, and they're significant because they can damage DNA and cause mutations.
by Sally Qiu 2E
Sun Nov 03, 2019 2:45 pm
Forum: Dipole Moments
Topic: Dipole moments
Replies: 5
Views: 42

Re: Dipole moments

a dipole moment occurs when atoms in a molecule share electrons unequally. this means there's a difference in electronegativity, and this creates partially negative and positive regions which gives the molecule ionic character
by Sally Qiu 2E
Sun Nov 03, 2019 2:28 pm
Forum: Dipole Moments
Topic: Hydrogen Bond
Replies: 7
Views: 46

Re: Hydrogen Bond

a hydrogen bond is a type of dipole-dipole interaction, but it's specifically between hydrogen and N, O, or F. it's the stronger than dipole-dipole because of the partially positive hydrogen atom and partially negative N O or F
by Sally Qiu 2E
Sun Oct 27, 2019 9:18 am
Forum: Lewis Structures
Topic: Drawing Lewis Structure
Replies: 6
Views: 36

Re: Drawing Lewis Structure

i would assume we have to draw the lone pairs since we haven't been told otherwise. just draw them to be safe
by Sally Qiu 2E
Sat Oct 26, 2019 10:30 pm
Forum: Quantum Numbers and The H-Atom
Topic: Ms and ML
Replies: 6
Views: 48

Re: Ms and ML

ml is actually the quantum number that is from -l to +l. it means that ml can take on integer values from -l to +l; for example, if l was 2, then ml can be -2, -1, 0, 1, or 2. and ms is either -1/2 or +1/2
by Sally Qiu 2E
Sat Oct 26, 2019 2:48 pm
Forum: Trends in The Periodic Table
Topic: Electronegativity vs Electron Affinity
Replies: 6
Views: 39

Re: Electronegativity vs Electron Affinity

electronegativity is how well an atom can attract electrons, or basically an atom's ability to attract electrons. electron affinity is the amount of energy released when an electron is added to a neutral and gaseous atom
by Sally Qiu 2E
Sat Oct 26, 2019 10:08 am
Forum: Trends in The Periodic Table
Topic: atomic radius
Replies: 3
Views: 23

Re: atomic radius

atomic radius is the distance from the nucleus to the outmost shell. i don't think we need to calculate it; i would assume the atomic radius would be either given to us in a problem, or we can solve for it with basic math (correct me if i'm wrong though).
by Sally Qiu 2E
Sat Oct 26, 2019 8:59 am
Forum: Resonance Structures
Topic: Bond Lengths
Replies: 5
Views: 256

Re: Bond Lengths

the electrons in resonance structures are delocalized, and this spreads multiple-bond character over the whole molecule. the resonance structures don't depict how the molecule actually looks like, so the bond lengths are the average between the single and double bonds
by Sally Qiu 2E
Sat Oct 26, 2019 8:54 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: ml alue (i.e., ...-1,0,1,....)
Replies: 2
Views: 22

Re: ml alue (i.e., ...-1,0,1,....)

the l value is determined by the n value, and ml is determined by l. ml can be any whole number from -l to +l; for example, if l=1, then ml can be -1, 0, and +1
by Sally Qiu 2E
Sat Oct 19, 2019 9:59 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Inner e- and Outer e-
Replies: 14
Views: 85

Re: Inner e- and Outer e-

the inner electrons "shield" the outer electrons from the electrostatic pull of the nucleus. this reduced electrostatic attraction is the "effective nuclear charge". this becomes important later when it comes to ionization and bonding
by Sally Qiu 2E
Sat Oct 19, 2019 12:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals vs. Shells
Replies: 5
Views: 43

Re: Orbitals vs. Shells

a shell is the energy level, which is n. orbitals are denoted by ml, and are the shapes that can hold up to 2 electrons. i'll attempt to give an example: n=2, l=1, so we have 2p. there can be 3 values for ml, so we have px, py, and pz. if you remember high school chemistry and electron configuration...
by Sally Qiu 2E
Sat Oct 19, 2019 11:57 am
Forum: *Shrodinger Equation
Topic: Concepts of Schrodinger equation
Replies: 3
Views: 27

Re: Concepts of Schrodinger equation

schrodinger's equation solves for a wave function (treating electrons as matter waves) and it can be used to find the relative location of an electron and the probability of finding an electrons in a location.
by Sally Qiu 2E
Thu Oct 17, 2019 4:57 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes
Replies: 7
Views: 62

Re: Nodal Planes

nodal planes are where the probability of finding electrons is zero. they're derived from schrodinger's equation
by Sally Qiu 2E
Thu Oct 17, 2019 4:47 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty application
Replies: 3
Views: 33

Re: Uncertainty application

in order to use the uncertainty equation, you need to have some value for mass. because photons have no mass, you cannot use the momentum equation p=mv and thus, you cannot calculate the uncertainty
by Sally Qiu 2E
Sat Oct 12, 2019 7:46 pm
Forum: Properties of Electrons
Topic: Electron Excitation
Replies: 6
Views: 31

Re: Electron Excitation

when an electron is excited, it means that it has absorbed energy and has jumped to a higher energy level.
by Sally Qiu 2E
Sat Oct 12, 2019 7:38 pm
Forum: Properties of Light
Topic: Speed of Light
Replies: 41
Views: 968

Re: Speed of Light

the speed of light changes depending on the medium it is traveling through; however, the constant 3.00x10^8 m/s is used when assuming the light is traveling through a vacuum. therefore, in our case, the speed of light is constant.
by Sally Qiu 2E
Fri Oct 11, 2019 9:43 am
Forum: Balancing Chemical Reactions
Topic: Balancing Chemical Reactions
Replies: 20
Views: 213

Re: Balancing Chemical Reactions

i try to balance the coefficient one by one by making a list, but when i get an odd number, I double the coefficients and that usually works out in the end
by Sally Qiu 2E
Fri Oct 11, 2019 9:41 am
Forum: Properties of Light
Topic: Speed of light
Replies: 9
Views: 56

Re: Speed of light

we use the constant c when we are assuming the situation is in a vacuum. however, it is true that light travels different under different mediums.
by Sally Qiu 2E
Fri Oct 11, 2019 9:37 am
Forum: Properties of Light
Topic: Converting units
Replies: 8
Views: 40

Re: Converting units

To convert from nanometers to angstroms, you multiply by 10.
by Sally Qiu 2E
Thu Oct 03, 2019 2:41 pm
Forum: SI Units, Unit Conversions
Topic: Sig Fig Mistakes
Replies: 17
Views: 185

Re: Sig Fig Mistakes

Letty Liu 1K wrote:Should we round off the numbers as we calculate or leave them as is until the final answer?
I was taught to not round as you calculate, as that would interfere with the accuracy of your final answer. Then, you can round and use the sig figs.
by Sally Qiu 2E
Thu Oct 03, 2019 10:17 am
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula Purpose
Replies: 13
Views: 156

Re: Empirical Formula Purpose

The empirical formula just shows the ratio between the atoms of a compound, and aids in finding the molecular formula.
by Sally Qiu 2E
Thu Oct 03, 2019 10:16 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook Question E15
Replies: 3
Views: 39

Re: Textbook Question E15

The (OH)2 is the hydroxide. The sulfide of the metal is going to have sulfur in the formula. I believe the problem wants you to find the mystery metal M, then find the formula of the sulfide of the metal.
by Sally Qiu 2E
Wed Oct 02, 2019 4:28 pm
Forum: Significant Figures
Topic: Quick General Question!
Replies: 5
Views: 87

Re: Quick General Question!

You've got me questioning my own knowledge on sig figs now, but I was taught that rounding was appropriate when doing sig figs. So 4.70 would be correct.
by Sally Qiu 2E
Wed Oct 02, 2019 4:24 pm
Forum: Empirical & Molecular Formulas
Topic: HW problem F9
Replies: 8
Views: 87

Re: HW problem F9

I'm not sure what you quite mean by the atoms "canceling out", but I would assume atom ratio refers to the subscript on the elements in the formula. More specifically the empirical formula.

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