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: 816
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: 1076
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: 343
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: 257
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: 522
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: 429
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: 524
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: 272
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: 371
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: 3133
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: 1003
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: 869
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: 1247
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: 257
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: 453
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: 367
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: 899
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: 779
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: 407
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: 623
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: 1401
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.
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: 399
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: 444
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: 711
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: 223
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: 859
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: 728
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: 256
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: 725
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: 326
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: 592
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?
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: 1286
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: 242
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: 354
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: 147
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: 830
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: 501
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: 850
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: 1748
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: 269
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: 408
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: 467
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: 582
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: 514
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: 343
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: 413
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: 1927
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: 290
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: 395
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: 546
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: 278
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)
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: 1449
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
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: 1706
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: 1458
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: 160
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: 1030
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: 500
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: 789
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: 1569
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: 1569
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?