Friday
November 28, 2014

Posts by Bun


Total # Posts: 67

chemistry
I am trying to calculate geometry optimization of cyclodextrin, however, the computer always show error 2070 in gaussian. I used sem-empirical pm3 and try pm6, and tried to find any method to do this work, but every try could not work. I hope any body on Jiskha can give me ...
May 28, 2012

physical chemistry
the aprroximate method to solve the shrodringer equation for hydrogen like atom? Please help, thank
June 4, 2011

inorg, chem
please help me to solve it, thank you so much in advance: propose organic compounds that are isolable with 1. Mn(CO)5(CpCo)(CpCo)C(Co(CO)4)3 2. Cr(CO)4(ì-PH)Cp*Mn(CO)
March 15, 2011

Algebra
-3x + 2y = 8 x + 4y = -4 use substitution method to solve the linear system.
February 22, 2011

phy. chem
start from the Maxwell-Boltzmann distribution and derive an expression for the most probable speed of a gas of molecules at a temperature T. Go on t demonstrate the validity of the equipartition conclusion that the average translational kinetic energy of molecules free to move...
January 23, 2011

chemistry, Please help.
Please tell me where I can find the articles ( free) to represent the Setvens rearrangement and Favorskii rearrangement. I have to have them for presentation but I have not taughed about these reaarangenment yet. I hope somebody on Jiskha will help me to find it. I really ...
November 9, 2010

chem
Ionic bonds and covalent bonds, which one is the stronger. My present teacher said that covalent bond is the strongest one. I learned ionic interaction is the strongest and many chem. books say so. Now i am confused. Is my present teacher right. Please explain this for me, and...
October 5, 2010

chemistry
mol Na2S = (0.01mol/L)*2.00ml*1L/1000mL = 0.002mol mol Hg(NO3)2 = 50.0ml*(0.0005mol/L)*1L/1000mL = 0.000025=2.5*10^-5 Hg(NO3)2 limiting reagent max mass of precipitate = 2.5*10^-5 * molar mass of Hg(NO3)2
August 13, 2010

chem
why we have to normalize the proton NMR areas to determine the mole % oa a compound in a mixture?
May 31, 2010

Chemistry
4.6*10^-3 = [NO2]^2/[N2O4] => [NO2] =3.48*10^-1
May 31, 2010

Chemisty
MnO4- +5e -> Mn2+}*2 C+1 -2e -> C+3 }*5 2MnO4- + 5C6H7O +6H+ -> 2Mn2+ + 5C6H7O2 + 3H2O Step 1: realize the oxidation of element: (oxidation of H and O not change) write half reaction equalize the number of election yieled and accepted by the coefficient ( here e yield...
May 31, 2010

physics
1.calculate the commutators a/ [x^2,p^2] b/ [a,a^+n] I don't know how to solve it. Please help. I really appreciate.
March 12, 2010

calculus
as t-->0, we have 8t-->0, so lim (sin(8t))^2/t^2 = [lim sin(8t)/t].[limsin(8t)/t] as8t-->0 =8.[limsin(8t)/8t].8[limsin(8t)/8t], 8t-->0 = 8*1*8*1= 64 you know the formula lim (sint/t)=1 as t-->1, aren't you?
March 6, 2010

calculus
y' = (3-secx)'tanx -(3-secx)(tanx)'/(tanx)^2 = -secx(tanx)^2 - (3-secx)secx/(tanx)^2 = -secx[(tanx)^2 + (3-secx)]/tan^2x =-[(tan)^2 +3 -secx]/sinx
March 6, 2010

chemistry
Br is larger than Cl,yet the two atoms have identical axial destabilization energies. Why?
March 6, 2010

Algebra
let y=0, --> x= 6/5=1.2 let x=0 --> y = 6/3 = 2
March 6, 2010

Algebra
They are correct b) (1.2,0) and(0,20
March 6, 2010

chemistry
deltaG = -RTlnK R=8.314J/mol.K you got R, T so K found by that formula.
March 6, 2010

chem
What is the chemical formula of fertilizer 13-13-13. Pleas tell me. Thanks a lot
February 7, 2010

chem
how many milliter of .246 M HNO3 should be added to 213 ml of 0.00666 M 2,2'-bipyridine to give a pH of 4.19? please help, does this problem need to be solved with ka or kb?. Is 2,2'- bipyridine a base, this is the problem from my text book, but it is not given by the ...
February 2, 2010

phys
show [f(xop), d/dx] = -df/dx please help, can sb gives a hint? I really appreciate.
January 28, 2010

phys
1) Pf(x)= f(-x), p operator Find the eigenvalues and eigenfunction of p 2)Show [f(xop), d/dx] = - df/dx
January 28, 2010

CHEM
increasing atomic radius: oxygen<carbon<aluminum<potasium
January 24, 2010

CHEM
neon<oxygen<sulfur<aluminum
January 24, 2010

chemistry
ionization energy is the minimum energy (Kj/mol)required to remove an wlectron from a gaseous atom in its ground state. affinity energy: the negative of the energy change that occurs when an electron is accepted by an atom in the gaseous state to form an anion
January 24, 2010

chem
Electronegativity of fluorine is the highest among the chemical element(its electronegativity = 4),so F tends to receive electron, not yield. Therefore, fluorine has the higher ionization energy than iodine.
January 24, 2010

chem
the properties of elements are based on the valence electron, the elements in the same family generally have similar properties because they have the same number of valence electron.
January 24, 2010

chem
Species of arsenic found in kriking water include (AsO3)3-, (CH3)2(AsO2)2-, (CH3)AsO3 2-, and (AsO4)3-. Pure water containing no arsenic was spiked with 0.40microgram arsenate/L. Seven replicate determinations gave 0.39, 0.40, 0.38, 0.41, 0.36, 0.35 and 0.39 mcrogram /L. Find ...
January 24, 2010

chemistry
6.2(+_ 0.2) - 4.1 (+_ 0.1 ) + ? [6.2( +_ 0.2) - 4.1(+_ 0.1)] : 9.43(+_0.05) find absolut uncertainty and relative uncertainty. PLEASE HELP:I solved them and got the exact absolute uncertainty like the answer key, but I didn't get right answer of relative unsertainty, my ...
January 18, 2010

chemistry
Why do the molecules that have the structures such as H2C=C=CH2 or HO-CH=CH2 are unstable?
January 13, 2010

phys
i solved D~11.7*10^-2, but the answer key is .0956
January 6, 2010

phys
Is D~11.7*10^-2
January 6, 2010

phys
What is the minimum lens size (in meters) that will permit just resolving 2 stars 1.1 second apart using light of 510nm?
January 6, 2010

MATH
Let x be the orders Harry sold y be the orders McDonal sold x + y = 60 (1) and y/x = 3 (2) s0lve this system x =15, y =45 after increase H. sold 15+15 =30 Mc. sold 15*6 + 45 = 135
December 30, 2009

chemistry
Thank you so much drwls
December 29, 2009

chemistry
Thank you drwls i am reviewing my chemistry and doing the problems from my textbook. Because my teacher did not have the lecture about this part, so I am reading my text book and trying to solve problems. My textbook only have two problems of this theory: 1/ find how many ...
December 29, 2009

chemistry
1. The mass spectrum can be observed for all forms: pos. ion, neg.ion, molecules, and atoms, can't it? 2. Is there a formular to calculate how many spectrum of the substances we need to observe? Please give me some examples, and calculation. 3. I knew the examples of H2S...
December 29, 2009

Chemistry
Ho is the element of the Lanthanide series, the Lanthanides have the electrons are arranged into the orbital 4f.If you start from the element La (Z= 57), write the electron configuration of La,Ce(Z= 58),..., to Ho(Z=67) , you will understand why Ho=[Xe]4f11 6s2, it cannot 6s2...
December 27, 2009

Chemistry
5f^14 and 5f^7 is stable ( 5f^7 : all spin is up), so you cannot drive 5f^8 instead of 5f^7 6d^1
December 27, 2009

math
-4y = -3x +4 divide by -4 -4y/-4 = (-3/-4)x + 4/-4 y = (3/4)x -1 the slope is 3/4 and the y intercept is -1
December 27, 2009

Chemistry
Yes
December 23, 2009

Algebra
(AB^2)/C - B^2 = (B^2)(A/C) -B^2(1) = B^2( A/C -1)
December 23, 2009

Pre Cal
cos^2 + sin^2 =1 cos^2 = 1-16/25 =9/25 sin theta terminates in quadrant II, so sin>0 but cos <0 therefore cos =-3/5
December 23, 2009

Math
there are 7 times Sean and Kevin have the probability to be selected as partners.
December 15, 2009

math
let the number be x so (x+8)(-4)-5=10 -4x-32-5=10 -4x=47 x=-47/4
December 15, 2009

science
It is not a homework, it is my question, and I hope it is explained. Sometimes at night I look ATTENTIONALLY at the starry sky , notice and see that there is an object which is as small as a star is moving. It is very very far and has the light as the light of a star, and I ...
December 15, 2009

Math
sure, you can say $1.70
December 15, 2009

Math
85/5.95= 14.28 so se can buy 14 cd the change = 8500-590*14= 170 cents
December 15, 2009

phys
Thanh you drwls
December 15, 2009

phys
It is not a homework,but this is my question and I hope sb to explain it for me: There is not snow is the area I am living, but in the winter, sometimes I see the ice on my car. I notice that the water is ALWAYS iced at the positions: roof-rack. the lid of the trunk, hood , ...
December 15, 2009

math
95/100 80/100 3/9 6/8 2/3
December 15, 2009

Calculus
{28/3[7/3(x^4/3) +11/5(x^2/5) +13)][x^7/3+11/7x^7/5+13x^7/7]^1/3}
December 13, 2009

algebra
= a*a- +2a -3a -6 = a(a+2)-3(a+2) = (a-3)(a+2)
December 11, 2009

algebra
4x^2 -20x +25
December 11, 2009

algebra
sorry I made mistake, the product is 6x^2 -x -2
December 11, 2009

algebra
6^x2-x-2
December 11, 2009

math
=x+y/(x+y)(x-y)/48 =48/x-y
December 11, 2009

chemistry
2molK + 1molClgas create 2molKCl nK/nClgas=2/1 5/39:7/31=1.3 so Cl gas excess mClgas(excess) = 7-(5*71/78) = 2.45g
December 11, 2009

Calculus
you can do like this: (4x^2-3)^1.5 = (4x^2-3).sq(4x^2-3)dx Let 2x = Sq3.sec(det) so, 4x^2 -3 = 3.sec^2(det)-3 = 3.tan^2(det) new INT= INt(3^1.5tan^3(det)d(det) Use Pythagore to solve the relation between x and the angle det.
December 10, 2009

physics
In a double slit experiment with a single electron, a very thin film of fluorescent material that emits a photon whenever an electron passes through is placed on one of the slits to check which slit the electrons goes through. Describe the resulting pattern on the detecting ...
December 10, 2009

physics
In a double slit experiment with a single electron, a very thin film of fluorescent material that emits a photon whenever an electron goes through. Describe the resulting pattern on the detecting screen if the experiment is repeated many times.
December 10, 2009

physics
Thank you drwls, My problem is a. The lifetime of the levels in a hydrogen atom are of the order 10-E8s. What is the evergy uncertainty of these states? Compare this result with the energy value of the first excited state. b. Find the shortest and the longgest wavelengths of ...
December 8, 2009

phys.
the shortest and longest wavelength series in singly ionized helium is 22.8nm and 30.4nm . Are they right? How many orders we can see between the angles range observations 30 and 90 in the Balmer's series?
December 8, 2009

physics
The atoms in gas ( gas constant R=8.31 J/mol K) can be treated as classical particles if their de Broglie wavelength L is much smaller than the average separation between the particles d. Consider monatomic helium gas (mHec^2 = 3727 MeV, molar mass 4g/mol) at 1.0 atmosphere of...
December 7, 2009

physics
The atoms in gas ( gas constant R=8.31 J/mol K) can be treated as classical particles if their de Broglie wavelength L is much smaller than the average separation between the particles d. Consider monatomic helium gas (mHec^2 = 3727 MeV, molar mass 4g/mol) at 1.0 atmosphere of...
December 7, 2009

Physics
The atoms in a gas (gas constant R=8.31 J/mol-K) can be treated as classical particles if their de Broglie wavelength ă is much smaller than the average separation between the particles d. Consider monatomic Helium gas (mHec2 = 3727MeV), molar mass 4g/mol) at 1.0 ...
December 7, 2009

Theory and History of Visual Communication
In shape relationships, what can you do to make objects or text seem like they are grouped together. How does repetition help create unity? Why would this be a helpful thing to do? Why would similarity in shapes create harmony? What could you do to keep harmony but make the ...
January 24, 2007

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