## Search found 61 matches

Thu Mar 14, 2019 1:52 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 7th edition 4F.11
Replies: 4
Views: 526

### Re: 7th edition 4F.11

is it because the pressure is also changing that you can't use the nCln(T2/T1) equation?
Mon Mar 11, 2019 10:53 pm
Forum: Balancing Redox Reactions
Topic: Oxidation vs Reduction Half Rxn
Replies: 9
Views: 430

### Re: Oxidation vs Reduction Half Rxn

i just remember that reduction reactions have electrons on the reactant side and it helps because they both start with the letter R
Mon Mar 11, 2019 10:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Constructing cell diagrams
Replies: 2
Views: 108

### Re: Constructing cell diagrams

you include H+ not H2O but the rest seems right
Mon Mar 11, 2019 10:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13
Replies: 1
Views: 99

### 5I.13

for the last part of the question, it asked which was more thermodynamically stable the disassociation of F2 or Cl2 and the answer is Cl2 because it has a smaller equilibrium constant but why?
Tue Mar 05, 2019 3:13 pm
Forum: Zero Order Reactions
Topic: 7A 15
Replies: 4
Views: 209

### Re: 7A 15

to calculate the degree for each reactant you have to compare each experiment and see how changing the concentration of one reactant impacts the total rate of the reactant. for element c, you can see in experiment 1 and experiment 4 the concentration of a and b aren't change but the concentration of...
Tue Mar 05, 2019 3:06 pm
Forum: General Rate Laws
Topic: 15.9 6th edition
Replies: 3
Views: 162

### Re: 15.9 6th edition

zero order reaction means that the concentration the reactant has no effect on the rate of the reaction so even if you increase the amount of reactant the reaction will proceed at the same time. the unit for the rate constant will be M/s
Tue Mar 05, 2019 3:03 pm
Forum: General Rate Laws
Topic: 6th edition 15.9
Replies: 4
Views: 204

### Re: 6th edition 15.9

i personally don't know the exact reason why but if you try it with the first reaction they give you in the chart (btw i have the seventh edition). the rate law = k[H2][I2] and if you're just considering the units for the problem the left side or the rate has units of M/s while the right side is L/m...
Wed Feb 27, 2019 8:25 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: BASIC VS ACIDIC METHODOLOGY
Replies: 1
Views: 110

### Re: BASIC VS ACIDIC METHODOLOGY

you got the two mixed up, for basic solutions you use OH- and H2O and for acidic solutions you use H+ and H2O, but the question should tell you whether or not they want you to balance the equation in a basic or acidic solution
Wed Feb 27, 2019 8:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Phases used in a Galvanic Cell
Replies: 3
Views: 145

### Re: Phases used in a Galvanic Cell

liquids are in the same like bracket as gases i believe
Wed Feb 27, 2019 7:55 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delta G naught when K<1
Replies: 3
Views: 753

### Re: delta G naught when K<1

i think it has to do with the fact that if K < 1 then there are more reactants than products at equilibrium so the reaction sits to the left making the reverse reaction favorable
Thu Feb 21, 2019 3:46 pm
Forum: Balancing Redox Reactions
Topic: Oxidation States
Replies: 10
Views: 426

### Re: Oxidation States

we don't have to memorize the oxidation states for transition metals since they could have more than one, but we should know the oxidation states of like carbon, hydrogen, and oxygen
Wed Feb 20, 2019 9:12 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Midterm Question
Replies: 5
Views: 434

### Re: Midterm Question

so is the answer that products are more stable
Wed Feb 20, 2019 9:08 pm
Forum: Balancing Redox Reactions
Topic: Week 7 Homework
Replies: 15
Views: 526

### Re: Week 7 Homework

mostly gibbs free energy
Tue Feb 12, 2019 1:38 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: hw 4f 17
Replies: 1
Views: 105

### hw 4f 17

i was reading the solution and i was wondering why do you have to find the entropy in three steps rather than two?
Tue Feb 12, 2019 1:36 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 7th edition 4F.11
Replies: 3
Views: 201

### Re: 7th edition 4F.11

i don't think you can use that equation with the 5/2R because the pressure isn't constant. since it's a compression if volume decrease then pressure increases
Tue Feb 12, 2019 1:05 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: temp units
Replies: 3
Views: 136

### temp units

when you're trying to find the entropy change of an ideal gas reversibly, do you use the equation with temperature in kelvin or celsius?
Wed Feb 06, 2019 7:38 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermic definition
Replies: 5
Views: 273

### Re: Isothermic definition

isothermal means temperature is constant so delta u is zero and isometric means volume is constant so work equals zero.
Wed Feb 06, 2019 7:36 pm
Forum: Calculating Work of Expansion
Topic: Pressure Units
Replies: 7
Views: 294

### Re: Pressure Units

Sophia Ding 1B wrote:Are we always supposed to being the unit for atm in terms of calculations with pressure?

i think it depends on which constants you use like if you use R = 0.08206 L atm/K mol then you use atm but they also give you R = 62.364 L Torr/K mol on the equation sheet
Tue Feb 05, 2019 9:45 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy unit
Replies: 3
Views: 154

### enthalpy unit

what are the units for enthalpy, is it just joules?
Thu Jan 31, 2019 7:04 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy
Replies: 4
Views: 224

### Re: Standard Enthalpy

since 02 is normally found as a diatomic molecule so there is no need to form the molecule which gives a zero enthalpy of formation
Thu Jan 31, 2019 6:09 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: steam vs. water
Replies: 5
Views: 309

### Re: steam vs. water

https://courses.lumenlearning.com/intro ... for-water/

i couldn't figure out how to insert a picture of the heating curve so here's a website.
this is for reference of the answer above mine.
Thu Jan 31, 2019 6:01 pm
Forum: Phase Changes & Related Calculations
Topic: HW problem 8.5
Replies: 3
Views: 162

### Re: HW problem 8.5

the system is the gas and everything else around it is the surroundings. heat is being added to the system so 524 kj is positive then work is being done to the system so 340 kj is also positive then the total change in internal energy is the two numbers added together.
Thu Jan 24, 2019 9:54 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Acids and Bases (weak or strong)
Replies: 3
Views: 179

### Re: Acids and Bases (weak or strong)

in terms of Ka values i think for weak acids the Ka value is very small compared to that of a strong acid but i dont know if that applies for weak bases
Thu Jan 24, 2019 9:45 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Solids and Liquids for pressure change
Replies: 3
Views: 153

### Re: Solids and Liquids for pressure change

i'm guessing it's because solids and liquids usually aren't affected by changes in pressure like gases are.
Thu Jan 24, 2019 6:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW 6A.21
Replies: 1
Views: 102

### HW 6A.21

for this problem they give you the Kw of water and it is 2.1 x 10^-14 and you have to find the hydronium and hydroxide concentration. in the answer explanation they made the two equal is it because it's water that hydronium and hydroxide equal?
Thu Jan 17, 2019 7:25 pm
Forum: Ideal Gases
Topic: K value
Replies: 8
Views: 327

### Re: K value

if k=1 wouldn't that mean that the reaction is at equilibrium?
Thu Jan 17, 2019 7:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Conjugate base
Replies: 7
Views: 339

### Re: Conjugate base

the conjugate base comes from an acid after it loses the proton, ie sulfuric acid H2SO4 its conjugate base is HSO4-
Thu Jan 17, 2019 7:15 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 7th Edition 5J.1
Replies: 3
Views: 105

### Re: 7th Edition 5J.1

the concentration H2 would increase because you want to keep the equilibrium constant the same so if you increase CO then the same would happen to H2
Sat Jan 12, 2019 4:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to use ICE tables
Replies: 5
Views: 317

### Re: How to use ICE tables

I'm still confused on how to find the change in molarity, can someone explain please? Does the number in front of the X come from the coefficient that is in front of the reactant or product? yes the coefficient of x is from the coefficients from the balanced equation. if the equilibrium concentrati...
Fri Jan 11, 2019 10:09 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equilibrium
Replies: 3
Views: 137

### equilibrium

can someone explain the so what of equilibrium like what can you do knowing what the equilibrium of a reaction is?
Fri Jan 11, 2019 10:07 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: defining Q
Replies: 6
Views: 291

### defining Q

so when you find q and you see that it is smaller than k then it means that the forward reaction is favored. my question is does that mean that the reaction needs to continue for a period of time before equilibrium is reached?
Wed Dec 05, 2018 10:28 pm
Forum: Naming
Topic: Spelling
Replies: 4
Views: 184

### Spelling

this may be a dumb question but is the ammonium ligand spelled amine or ammine?
Wed Dec 05, 2018 9:28 am
Forum: Ionic & Covalent Bonds
Topic: Bond Lengths
Replies: 5
Views: 430

### Re: Bond Lengths

i find bond lengths by doing lewis structures. single bonds are the longer, weaker bonds. double bonds are in the middle. triple bonds are the shorter, stronger bonds.
Wed Dec 05, 2018 9:16 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: unit
Replies: 3
Views: 128

### Re: unit

the concentration should be in moles/liter (M)
Tue Nov 27, 2018 9:02 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 temperatures and hydrogen bonds
Replies: 2
Views: 127

### Re: Boiling temperatures and hydrogen bonds

H2S does not have hydrogen bonds because hydrogen bonding only occurs when a hydrogen bonds with oxygen, fluorine, and nitrogen. H2S has dipole-dipole because when you draw out the lewis structure you see it is polar. H20, on the other hand, has hydrogen bonds and since hydrogen bonds are the strong...
Tue Nov 27, 2018 8:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Homework 6th Edition 4.13
Replies: 1
Views: 94

### Re: Homework 6th Edition 4.13

it's not t-shaped because t-shaped would have three bonds attached to the central atom and two lone pairs (AX3E2) but it is linear because i think the three lone pairs on the central iodine balance out the three lone pairs on the other two iodine.
Mon Nov 19, 2018 2:06 pm
Forum: Trends in The Periodic Table
Topic: Ionization energy
Replies: 4
Views: 417

### Re: Ionization energy

ionization energy is the energy to remove an electron and it decreases as you move across a period. it decreases because the more electrons an atom has the stronger the attraction it has towards the nucleus making it harder to remove an electron. magnesium has more electrons so it is harder to remov...
Mon Nov 19, 2018 2:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles of H3O+
Replies: 2
Views: 73

### Re: Bond angles of H3O+

the orientation would be in a tetrahedral shape and the angle would be less than 109.5
Mon Nov 19, 2018 2:01 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Double bonds
Replies: 8
Views: 258

### Re: Double bonds

double bonds do not affect the vsepr model because they are thought of as single regions of electron density and for lone pairs you draw an electron cloud
Wed Nov 14, 2018 9:43 am
Forum: Electronegativity
Topic: Electronegativity in Molecules with N,O,F
Replies: 4
Views: 396

### Re: Electronegativity in Molecules with N,O,F

NF3 has hydrogen bonding because the hydrogen is bonding with the very electronegative nitrogen. this molecule is polar which makes it dissolve in water.
Wed Nov 14, 2018 9:26 am
Forum: Determining Molecular Shape (VSEPR)
Topic: The A in the VSEPR Formula [ENDORSED]
Replies: 4
Views: 95

### Re: The A in the VSEPR Formula[ENDORSED]

A represents the central atom and there can only be one central atom so no subscript is needed
Wed Nov 14, 2018 9:19 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape
Replies: 5
Views: 180

### Re: Shape

they are the same shape
Thu Nov 08, 2018 10:00 pm
Forum: Sigma & Pi Bonds
Topic: sigma/pi bonds and bond order
Replies: 2
Views: 239

### Re: sigma/pi bonds and bond order

sigma bonds are single bonds and pi bonds are double or triple bonds. the bond order is the number of bonds between two elements.
Wed Nov 07, 2018 1:04 pm
Forum: Dipole Moments
Topic: HCl
Replies: 6
Views: 202

### HCl

in lecture, lavelle was talking about how HCl has a permanent dipole moment and I was wondering how do we know that.
Wed Nov 07, 2018 9:05 am
Forum: Trends in The Periodic Table
Topic: electron affinity
Replies: 2
Views: 347

### Re: electron affinity

no because electron affinity is the energy released when an electron is added but since the noble gases have fulled valence shells it requires energy to add an electron so the elements with the highest electron affinity are in the top of group 17.
Wed Nov 07, 2018 8:59 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electron configuration of Niobium
Replies: 2
Views: 185

### Re: electron configuration of Niobium

[Kr] 4d4 5s1
Wed Oct 31, 2018 9:27 am
Forum: Ionic & Covalent Bonds
Topic: 6th Edition, Question 3.5
Replies: 3
Views: 207

### Re: 6th Edition, Question 3.5

copper has the electron configuration [Ar] 3d10 4s1 because it is more stable to have a full d shell than a partially full d shell and a full s shell. also since the 4s shell has more energy you take the electrons from that shell first so you're left with Cu 2+ as [Ar] 3d10
Wed Oct 31, 2018 9:19 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ag+ Configuration
Replies: 5
Views: 1126

### Re: Ag+ Configuration

Ag has the electron configuration has [Kr] 4d10 5s1 when you take one electron out of the shell it comes from the highest energy which is 5s shell and it is also more stable to have the full d shell than a full s shell.
Wed Oct 31, 2018 9:15 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 6th Edition Problem 3.9
Replies: 1
Views: 145

### Re: 6th Edition Problem 3.9

since the electron configuration shows only the 3d and 4d shell so it is implied that the 4s shell was taken first because it has the higher energy. for the first one the two electrons are coming from the 4s shells and the final configuration is [Ar] 3d7 4s2 which is Cobalt so the ion is Co 2+.
Tue Oct 23, 2018 10:59 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Writing an Electron Configuration Format
Replies: 3
Views: 181

### Re: Writing an Electron Configuration Format

they are essentially the same thing just when if a question asked how many electrons are paired in the first way you wrote it you know the last two electrons aren't paired and are parallel
Tue Oct 23, 2018 10:57 pm
Forum: Quantum Numbers and The H-Atom
Topic: Magnetic Quantum Number
Replies: 5
Views: 312

### Re: Magnetic Quantum Number

I don't think we need to know the specific axis pairing. I think we just need to know that the d orbital has five different pairings
Tue Oct 23, 2018 10:53 pm
Forum: DeBroglie Equation
Topic: deriving DeBroglie
Replies: 2
Views: 183

### Re: deriving DeBroglie

c = λv (v is frequency)
p = mv
E = pv (v is velocity)
for a photon the speed is the speed of light so E=pc and E=(hc)/ λ
so pc=(hc)/ λ
λpc=hc
λ = h/p (de Broglie)
Fri Oct 19, 2018 9:41 am
Forum: DeBroglie Equation
Topic: 6th HW 1.23 What is KeV?
Replies: 5
Views: 490

### Re: 6th HW 1.23 What is KeV?

eV = electric volt which is the amount of energy in an electron
KeV = kilo-electric volt so multiply that quantity by 10^3
there is 1.602 x 10^-19 J = 1 eV
then you would proceed by using E = hc/lambda
Fri Oct 19, 2018 9:18 am
Forum: Properties of Light
Topic: Do I have to memorize the spectrum?
Replies: 20
Views: 808

### Re: Do I have to memorize the spectrum?

I think you should know which wavelengths correspond to visible light (400 nm -700 nm) and know the order of smallest to longest wavelengths (gamma ray, x-ray, ultraviolet, visible, infrared, microwave, and radio wave)
Wed Oct 17, 2018 9:11 am
Forum: Quantum Numbers and The H-Atom
Topic: Lyman, Balmer, Pascal
Replies: 10
Views: 749

### Re: Lyman, Balmer, Pascal

They refer to the different special lines electron transition to. So for the lyman series means that electrons transition to the first energy level (n1), balmer series transition to the second energy level (n2), and paschen series transition to the third energy level (n3)
Wed Oct 10, 2018 3:32 pm
Forum: Properties of Light
Topic: Problem 1.9 6th Edition
Replies: 2
Views: 62

### Re: Problem 1.9 6th Edition

you would begin by converting the megahertz to hertz by using the conversion factor that 1 MHz = 1,000,000 Hz then whether you're given energy, wavelength, or frequency you would use the equation speed of light = wavelength x frequency or energy = planck's constant x frequency.
Wed Oct 10, 2018 3:25 pm
Forum: Einstein Equation
Topic: Units
Replies: 5
Views: 290

### Re: Units

hertz is equivalent to per second (1 s^-1) so in the equation E=hv, h has units of J x s and v has units of 1/s so when you multiply the two cancel out to get J which is the unit for energy
Sun Oct 07, 2018 10:26 pm
Forum: Properties of Light
Topic: Speed of light constant (c)
Replies: 6
Views: 190

### Re: Speed of light constant (c)

The amount of sig figs in the constant should not affect the amount of sig figs in the final answer; only the amount of sig figs in the calculated values affect the answer.
Thu Oct 04, 2018 8:47 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant vs. Reagent??? [ENDORSED]
Replies: 6
Views: 342

### Re: Limiting Reactant vs. Reagent???[ENDORSED]

They are the same thing. Reagent would be what you physically have in the lab and reactant is what you would read and write on paper.
Wed Oct 03, 2018 9:15 am
Forum: Balancing Chemical Reactions
Topic: Balance Equation L.35
Replies: 6
Views: 604

### Re: Balance Equation L.35

Thank you I got the balancing equation now but now I am trying to convert tons to kilograms but the appendix has two different values ( 907.18474 kg or 1016.046 kg) so I don't know which one to use.
Tue Oct 02, 2018 10:17 pm
Forum: Balancing Chemical Reactions
Topic: Balance Equation L.35
Replies: 6
Views: 604

### Re: Balance Equation L.35

I am also confused about this problem because I could balance the first two equations but I am unable to balance the last equation (Fe3Br8 + Na2CO3 ---> NaBr + CO2 + Fe3O4) so how should I about balancing the final equation?