~christina~

Newest questions posted by ~christina~
  1. chemistry

    I have a question about m-Phenylenediamine. Is m-Phenylenediamine the same as m-Phenylenediamine hydrochloride? I apparently have to use the latter for a chemical test but we only have a bottle that is labeled as the former. Is it okay to use that and just
  2. Dr.Bob - Question

    I'm know I'm interested in the chemistry field. The problem is that I have to further narrow down my field of interest. I was curious to know what type of chemistry did you specialize in in the past. -christina
  3. citation of UNEP PDF online assessment/report

    How would I cite a document from the UNEP website? (PDF document) APA style? I've been looking but it looks like you have to cite it a special way? Is this true? I cannot personally find the, "session" or etc. It is a document evaluating the environment,
  4. science(chem)

    I have a question about compounds that oil out of solvents after drying. How would I analyze this? Could I make a KBr pellet, or would I just be able to analyze it in UV spec? I assume that the solvents used to dissolve the compound, would be used as a
  5. english

    I have a general problem with not being able to determine when it is appropriate to use semicolons. I usually use appostrophes and it is incorrect, of course. Is there a way to recognize the place where a semicolon should go? The examples I have seen are
  6. science(chemistry)

    I have a question about TLC plate solvents. What solvents will leave stains on a plate with a TLC plate out of the ones below and why?) (n-Octane, n-Hexane, Decane, Acetone, 1-Propanol, 2-Propanol, Ethanol, Toluene, Cyclohexane, Methanol, n-Heptane,
  7. science(chemistry) -Q for Dr.Bob

    solvent layer: 1 solid precipitate: no I ran the solvent layer I got in my unknown in the GC and I had sharp peaks in the beginning but at about 4 min on the polar column, I got a broad peak that tailed off considerably. question is, Is it water? I'm not
  8. science(chemistry)

    When performing vacuum filtration of a solid in an unknown solvent, is it necessary to go and find out the solvent composition, so that some fresh solvent can be used to wash the filtrate with?
  9. science(chemistry)

    I have a question about solvent evaporation. If I had an organic layer and an aqueous layer in an unknown mixture of liquids and wanted to obtain the solid of a compound(s) dissolved in the layers, is it reasonable to assume that I can run the compound in
  10. science(chemistry)

    How would I compare using peak heights vs peak areas for GC quantitation? Thanks
  11. Dr.Bob, response to your reply to last answer

    Sorry, I didn't see this. Actually you have only one mixture; it happens to have two components. There is a more or less standard procedure for separating complete unknowns (that's where you know nothing about it) and if you know nothing about it that is
  12. chemistry- Dr.Bob, can you help me out please?

    If I had two unknown chemicals (in solid form) mixed together, how could I go about identifying the individual components of the mixture? Is it possible, by UV, IR, GC, or HPLC? The problem I have is that with: GC= sample is destroyed & if you don't know
  13. science(chem)

    If I have a graph of concentration in Absorbance at 400nm vs [micromolar]of para-nitrophenol The slope would be the extinction coefficient. (y=mx) if forced through 0 The problem is what is y? I know y is the absorbance but it's given on a paper i have as,
  14. Graphing interpretation

    What would it mean if the line of a linear regression graph went through the origin? If it doesn't go through the origin and I make it go through the origin, what am I doing? I was looking for the answer to this and all I came up with was that if the line
  15. science(chem) Dr.Bob Question from before

    The only reason I asked about the balance is that most analytical balances in use in schools weigh to the nearest 0.1 mg although that may have changed since I retired. There are semi-micro balances that weigh to 5 places and micro-balances that weigh to 6
  16. science(chem)

    I'm making different concentrations of ethanol and I just wanted to check my calculations and method. Making ethanol concentrations of: 0.40% 0.30% 0.20% 0.10% 0.05% To make the 0.40% ethanol from stock solution using 100ml volumetric flask: (xg
  17. science(chem)

    The pKa of HEPES is 7.55 at 20C and it's MW is 238.31. Calculate the amounts of HEPES in grams and of 1.0M NaOH in ml that would be needed to make 300ml of 0.2M HEPES buffer at 7.2. I'm not sure how to go about doing this problem. Help please.
  18. science(chem) Dr.Bob Question from before

    I'm doing an experiment and I'm supposed to have neutral basic and acid samples of solution. I just wanted to make sure that I knew which was which. (If I'm incorrect, please correct me) Acid: 0.7ml 10% H2SO4 + 0.7ml 10% Na2WO4(sodium tungstate) Basic:
  19. science(chem)

    I'm doing an experiment and I'm supposed to have neutral basic and acid samples of solution. I just wanted to make sure that I knew which was which. (If I'm incorrect, please correct me) Acid: 0.7ml 10% H2SO4 + 0.7ml 10% Na2WO4(sodium tungstate) Basic:
  20. science(chem)

    I was wondering how does one make a saturated chemical solution? I'm supposed to make one, is there a way I can determine the ammount solute needed for a certain amount of solvent? If not, how do I make a saturated solution? Thank you
  21. science(chem)

    I need help finding information on how the conway microdiffusion is done/how it works. And why the sample is titrated. Thank you
  22. science(chem)

    I need help finding information on how the conway microdiffusion is done/how it works. And why the sample is titrated. Thank you
  23. science(chem)

    UV I was just wondering how a solvent would affect the spectra of a compound. Like a polar or nonpolar solvent for example: polar: Methylene chloride Nonpolar: cyclohexane, hexane, or ethanol Thanks
  24. science(chem)

    I was just wondering if it was necessary to remember each branch of chemistry learned. I can't really remember general chemistry and I'm sort of loosing the organinc. I mostly remember the calculations and the starting part of each course, but other than
  25. Law

    can someone give me a site that tells me the order of the courts in a state? I don't want to say the state but if needed I will (not sure if each state is different) My teacher isn't clear and thinks that the whole class took law.. divisions civil apella
  26. Who is correct? (chemistry issues here)

    how can this person say that I googled info? (I created it randomly out of my head) and be so ungrateful that I spent the time out of my day to help? Or is it I don't know what I'm talking about and a "condensed structure" is not the answer to the homework
  27. science(chem)

    Commercial hydrazine is sold as a 64% solution. Using that as your starting material, how would you prepare a 5% solution of hydrazine? well if it is sold as 64% solution would that mean that it has 64g of hydrazine per 100ml of solvent(water)? and what
  28. science(chem)

    Commercial hydrazine is sold as a 64% solution. Using that as your starting material, how would you prepare a 5% solution of hydrazine? well if it is sold as 64% solution would that mean that it has 64g of hydrazine per 100ml of solvent(water)? and what
  29. mistakes?

    hm..I was wondering If someone (cough* me) makes mistakes in answering questions, should they bother answering anything at all? Just a thought that crosses my mind alot. =/
  30. Physice....help please

    not understanding how to do this. A certain storm cloud has a potential of 1.00x10^8 V relative to the tree. If during a lightning storm, 50C of a charge is transfered through this potential differnce and 1.00% of the energy is absorbed by the tree, how
  31. Factoring

    (100)d^2-(57.3)d= 0 solve for d. yes...I just can't figure out what number I'd use to factor this and it got bumped to the next page. I thought it was an easy question but... Thanks
  32. math?? factoring

    100N/m d^2 - 57.3d= 0 sigh...I can't figure out how to find d know it's factoring but as to actual number to factor out...not so sure. Thanks
  33. science(chem)

    Can someone tell me if this objective for my lab report sounds alright? The objective of this multistep lab was to ultimately synthesize 4-bromo-2-chloro-6-iodoaniline through the intermediate formation of acetanilide, 4-bromoacetanilide,
  34. science(chem)

    My lab teacher told me to leave my sample mixture of 2-bromobutane and 2-chlorobutane in a solution 1-2ml of sodium bicarbonate. Then I asked after I had wrapped it up, whether there would be a reaction if I left it there for a whole week since that's what
  35. science(chem)

    I have a question about distillation. Or heating in general. When something says heat for 1hr or 1/2 hr do you start counting when you turn on the hotplate? Or do you start counting when the mixture is boiling? I have a feeling that this issue is affecting
  36. Dr.Bob

    I was wondering if I'm synthesizing a product in the end. I shouldn't put the end product of each reaction on the front page as well right?
  37. chem-> front page report

    wondering if this looks good or should I make the format some other way. Multistep Synthesis of 4-Bromo-2-Chloro-6-Iodoaniline name school Chem###sec## Multistep A,B March 13,2008 Multistep C March 20,2008 Multistep D March 27, 2008 Multistep E April 03,
  38. science(chem)

    Ka/Kb for the acetanilide being told that on the basis of this it will tell me whether a nitrogen or oxygen are protonated... (molecule: 4-bromoacetanilide) Thanks
  39. science(chem)

    NaClO3 + H2O + HCl=> what form is the Cl in ? I know that a gas is formed but the reaction that I did also had Cl reacting with the reactants so I'm not sure in what form of Cl did my reactant react with the product of the above reaction. Thanks
  40. chem

    Br + CHCOOH
  41. Photography club

    I was thinking about how clubs get started in college in the first place. For example there is a club for different ethinicities. How do these become "clubs"? I would think someone would have to take an interest in specific things first of all. But is this
  42. Physics=> quadradic equation

    book says: (4-4.00x + x^2)(6.00x10^-6C)= x^2(15.0x10^-6C) they got: 3.00x^2+ 8.00x-8= 0 I don't get how they got that quadradic equation. (I mulitplied over and then divided the 15.0x10^-6 over and I didn't get what the book got) (my problem that I'm doing
  43. Physics-not sure how to find the charge q

    Posted by ~christina~ on Sunday, March 30, 2008 at 9:14am. Two small silver spheres with a mass of 10.0g, are separated by 1.00m. Calcuate the fraction of the electrons in one sphere that must be transfered to the other to produce an attractive force of
  44. Physics..an electric field

    4 charged particles are at the cornedrs of a square of side a as shown. a) determine the magnitude and direction of the electric field at the location of charge q b) what is the total electric force exerted on q? basically picture is like this below It's a
  45. Physics... Coulomb's law

    Two small silver spheres with a mass of 10.0g, are separated by 1.00m. Calcuate the fraction of the electrons in one sphere that must be transfered to the other to produce an attractive force of 1.00x10^4 N (about 1 ton) between spheres (number of
  46. science(chem)

    What would cause the peaks in a IR analysis to be smaller than they should be? My sample had the right peaks where they should be and they were the right shape but were shorter then they should be. Something different is what the y axis says on the IR
  47. from pg 2...Dr.Bob.

    Sorry but I have just a few more Q'sfrom what you said And something that I saw today. Actually I was talking about specific course exams. I've been out of touch for awhile so I don't know all the rules about GRE, SAT, GMAT, etc. Do you mean that I ask
  48. Dr.Bob

    I replied to that post from yesterday. I don't know if you saw it.
  49. Physics (forgot to post this question #2)

    During the compression stroke of a certain gasoline engine, the pressure increases from 1.00atm to 20.0atm. If the process is adiabatic and the fuel air mixture behaves a a diatomic ideal gas a) by what factor does the volume change b) by what factor does
  50. physics => really need help on 2 problems (#1)

    A house has well insulated walls. It contains a vol of 100m^3 of air at 300K a) calculate the E required to increase the T of the diatomic gas by 1.00C b) If this E could be used to lift an object of mass m through a height of 2.00m what is the mass of m?
  51. Advice...about chemistry degree Dr.Bob

    Based on the question topic posted by Britney below titled:In your opinion (your answer to this reminded me of something) (I posted the same thing there but I thought it was improper to piggyback on that post so I posted this under a new topic) I don't
  52. Dr.Bob

    welcome back =) and happy easter too.
  53. American Lit => Ms.Sue (Poetry analysis help)

    Poem "for rosa parks" And how was this soft-voiced woman to know that this was "No" in answer to the command to rise would signal the begining of the time of walking Soft the word like the closing of some aweful book, a too-long story with no pauses for
  54. K => I answered your question at bottom or next pg

    I helped the best I could on your organic chem question
  55. Physics => waves

    It's a simple problem I think but I can't get the answers to match with the book. A particle fingering flute sounds note with frequency of 880Hz at 20 deg celcius(343m/s => sound wave speed) The flute is open at both ends. a) find the air column length b)
  56. science(chem) Dr.Bob-> need help on this long lab

    For 1 part of the lab I: prepare 4-Bromo-2-chloro-6-iodoaniline I dissolve 250mg recrystallized 4- Bromo-2-chloro-6-iodoaniline in 4ml of glacial acetic acid in 25ml erlenmyer flask and add 1ml water to the mixture. Then I prepare a solution of 250mg
  57. Dr.Bob the question Ihad reposted (NOT the old one

    Yes...another calculation problem. Rxn: 1ml isopentyl alcohol + 1.5ml glacial acetic acid + 3 drops sulfuric acid=> isopentyl acetate to calculate the theoretical yield.. I know that the acetic acid is in excess but how would I calculate the theoretical
  58. Dr.Bob => Can you see the post down the pg by me

    I'm trying to post this again..(assuming you didn't see the one below) I posted a question yesterday. I was hoping to catch you before you left on your getaway. =D
  59. Dr.Bob can you check out the question down the pg

    I posted a question yesterday. I was hoping to catch you before you left on your getaway. =D
  60. Some Lab Question (s)

    Yes...another calculation problem. Rxn: 1ml isopentyl alcohol + 1.5ml glacial acetic acid + 3 drops sulfuric acid=> isopentyl acetate to calculate the theoretical yield.. I know that the acetic acid is in excess but how would I calculate the theoretical
  61. Dr.Bob=> interesting rxn

    I was looking at a few videos online. If you type in "top ten amazing chemistry videos" into google and click the first link (wired science), you'll see what I'm speaking of. Well the thing is, I'm curious about the rxn in video # 6. It was described as
  62. science (chem)

    I have a question. I'm forming Isopentyl acetate by the esterfication of acetic acid with isopentyl alcohol. The rxn is shifted so that the ester is produced by using excess acetic acid. In isolating the ester, the excess acetic acid and and isopentyl
  63. Physics..=> drwls - I need your help

    I need help seeing if my thoughts are correct and how to do some things. Block 1 of mass 0.200 kg is sliding to the right over a frictionless elevated surface at a speed of 8.00 m / s. The block undergoes an elastic collision with stationary block 2, which
  64. Plastic Moulds ==> Couldn't find anything myself

    I'm proposed a way I'd synthesize plastic...polyethylene to shape into a pipe PROBLEM: not sure how or what I would use to make a mold or best method to produce a PIPE not sure what a mold should look like to produce a hollow object like a pipe. OR what
  65. Forced Oscillation - drwls => I need your help =)

    A 2.00kg object attatched to a spring moves without friction and is driven by an external force given by F= (3.00N)sin(2pi*t) The force constant of the spring is 20N/m. Determine a) period b) amplitude of motion a)T= 2pi/omega T= 2pi/ 2pi= 1s b)A= (Fo/m)/
  66. Physics => speed of sound variation

    The speed of sound in air (m/s) depends on temperature according to aprox expression of v= 331.5 + 0.607 Tc Tc= temp in celcius In dry air, temperature decreases about 1deg celcius for every 150m rise in altitude. a) assume the change is constant up to
  67. Physics - drwls can you help me with this?

    A 2.00kg block hangs from a rubber cord, being supported so that the cord is not stretched. The unstretched length of the cord is 0.500m and it's mass is 5.00g.The "spring constant" for the cord is 100N/m. Block is released and stops at lowest point. a)
  68. science(chem) plastic hedache...can anyone help?

    My hwk Q that I was trying to find the answer to yesterday is this below but I don't know exactly how the placticizing process works. I compiled the chemicals I think I need but other than that I'm stumped as to how to put them together or how. Q: A water
  69. Dr.Bob => nylon question posted again.since nxt pg

    new in bold (copied in normal text) 0.5g hex (1mol/116.21g)= 0.004302mol hex 0.5g adi (1mol/183.03g)= 0.002731mol adi Limiting: 0.002731mol adi(1mol nylon/1mol adi)(226.319g/1mol nylon6.6)= 0.61807 g Nylon Supposed to have theoretically: 0.61807g Nylon
  70. Dr.Bob

    could you check the next page where I replied to the post from yesterday pertaining to nylon calculations. Thanks C
  71. science(chem)

    I synthesized Nylon in my lab for organic chem. I need help figuring out the theoretical yield so I can compare it to my product that I synthesized. I looked up the reaction online on Google by typing in "Synthesis of adipoyl chloride and nylon 6.6." I
  72. science(chem)

    Hi =) I have two Q's 1. What are the 2 purposes of using a caffine standard during the HPLC process? In general not talking about HPLC I would think a standard is for a)comparing to your own results to see how good your results came out. b) seeing if you
  73. Physics

    A person can lift 45 kg ( aprox 100lb). Using specific gravity as 10.17 How many cubic meters of the metal could the person lift in a) air ? b) water ? c) in water ? Thanks
  74. Physics Archimedes buoyancy lab

    In calculating the density of a heavy solid. The string holding the heavy solid will cause error. specific gravity= (mass object in air)/ (mass object in air- mass object in water) = density When does it lead to an experimental density that is too high?
  75. NH4Cl

    NH4Cl Is it N surrounded by 4 H's and then the Cl is connected to a H?? Technically I think that couldn't happen so how would this molecule look? Thanks
  76. spin of a electron

    I have to know the spin of a electron and what I have in my notes has me confused. 1. If the # of neutrons and # protons of a element are odd the element has a whole spin # (1, 2, 3) examples given: 2 H 11 B 14 N 17 O 33 S 35 Cl (I think those are mass
  77. PHYSICS (what is a dynamic equation????)

    A car of mass Mc is connected to mass m2 by a string. The string passes over a solid cylindrical pulley, which has a frictionless bearing, of radius R and mass M. when the system is released from rest the string doesn't slip, the car moves down the
  78. lab equipment (chem)

    Why is it that in particular experiments they say to use a Hirsch funnel while we have both the Hirch funnel and the buchner funnel at our disposal. In my opinion I prefer to use the buchner funnel to using the Hirch funnel because product gets stuck in
  79. chemical test

    I'm going to do the Baeyer test (Pottasium permanganate) Instructions say to disslove 25mg of unknown or 2 drops of liquid unknown in 2ml of 95% ethanol. Slowly add 1% aqueous solution (weight/volume) of potassium permanganate, drop by drop with shaking,
  80. science(chem)

    I did a dehydration rxn with 1.424g of 4-methylcyclohexanol with .40ml 85% H3PO4 and 6 drops of concentrated H2SO4. I have to calculate the limiting reagent even though I do suspect it to be the 4-methylcyclohexanol. I do know the ratio is 1mol H3PO4: 3mol
  81. science(chem)

    Thanksgiving: this occured. Ham was being served at the dinner. The ham was marinaded with lemonade. This is served every year and I've only eaten it once. (not too fond of the odd taste [sort of like pinapple ham]) argument: I was told that coldcuts
  82. chem

    I had to go and do a oxidation- reduction lab where: I went oxidized borneol with sodium chloride and added 0.360g racemic borneol, 1ml acetone, and .30ml glacial acetic acid. Then I heated and added through the condenser every 4 minutes .5ml 6% sodium
  83. Physics...seriously seriously need help esp part C

    The coordinate of a 2.00kg object in linear motion is described by the function: x(t)= (2.00m/s^3)t^3 -(7.00m/s^2)t^2 + (7.00m/s)t for the time interval t= 0s to t= 2.00s. The center of mass of this object can be treated as a point particle. a) find change
  84. science(chem)

    How would I make a 5% solution of sodium bisulfite? sodium bisulfite: NaHSO3 Molar mass: 104.06 g/mol is it 5% w/w or v/v or w/v b/c if it was w/w then it would be weight percent w/w= weight solute/ weight solution* 100 I need help on this Thanks
  85. science(chem)

    How do I analyze a HPLC result? The lab tech injected the sample into the machine and I have the result paper for the sample injected which was caraway oil. However I'm not sure what to do with this now. It was recorded in volts per minutes. Thanks
  86. drying agent in chem

    Is it advisable or not to leave a solution in drying agent for a few days? ~I did this ..since my chem lab instructor said to but I'm not sure I believe him. He sounded unsure of himself when he answered me. solution: methylene chloride (extracting oil of
  87. sand bath (chem)

    what are disadvantages and advantages of using a sand bath to heat something in chem?
  88. physics PLEASE HELP (very very confused)

    2 blocks are connected by a rope of negligible mass are being dragged by a horizontal force. Suppose F= 68.0N, m1= 12.0kg, m2= 18.0kg and the coefficient of kinetic friction between each block and the surface is 0.100. a.) draw free body diagram for each
  89. science (chem) Rf values

    consider a sample that is a mixture of biphenyl, benzoic acid, and benzyl alchohol. The sample is spotted on a TLC plate and developed in a methylene chloride cyclohexane mixture. Predict the relative Rf values for the three components in the sample. For
  90. science (chem)

    consider a sample that is a mixture of biphenyl, benzoic acid, and benzyl alchohol. The sample is spotted on a TLC plate and developed in a methylene chloride cyclohexane mixture. Predict the relative Rf values for the three components in the sample. For
  91. science(chem)

    [b]1.[/b]Is TLC a qualitative or quantitative analysis? Is there any way that it can be both? Explain. ~I say it can be both since it can be used to go and determine what exactly is in a sample of mixed compounds which would be qualitative analysis. It can
  92. polarity

    hexane acetone water methanol -order from most to least polar... ~water/methanol, acetone, and hexane.. I can't decide which order does the 3 first go in... Help please...
  93. Polarity and electronegativity (science)

    Describe the concept of polarity. How is polrity related to electronegativity? ~Well I think that polarity is how I remember it.."pull" basically due to the tendency for electronegative atoms in a molecule to attract the other electrons in the other atoms
  94. science(chem)

    Consider the following errors that could be made when running the TLC. Indicate what should be done to correct the error. a) A 2 component mixture containing 1-octene and 1,4- dimethylbenzene gave only 1 spot with and Rf value of 0.95. The solvent used was
  95. science(chem)

    I was told before that it takes 2 mol of fluorene to be reduced by 1mol of sodium borohydride.... How many mg of fluorenone can 0.53 mol of sodium borohydride(NaBH4) reduce? what I got... 0.53mol NaBH4 ( 2mol fluorenone/ 1mol NaBH4)(180.192g/1mol
  96. science(chem)

    For the reaction: acetic acid (2g) + Isopentyl alcohol (0.9g) => Isopently acetate(1.15g)+ H2O I'm suposed to determine the limiting reagent, theoretical yield and percent yield from this reaction but the reaction was given as a picture... I'm not sure
  97. science(chem)

    How many mg of fluorenone can 0.53mol of sodium borohyride(NaBH4) reduce? ~I don't know how to get this..wouldn't I have to have a reaction equation given to me?? Well I didn't have one for the question given to me so I don't know what to do. I tried
  98. Vector Table (physics)

    I have to find the magnitude and direction of a resultant vector from values obtained from a vector table. The values in the book that we had to follow and put on the balancing part of the weight table were in F1= (0.200)g N when calculating the value for
  99. Fluorenol (In the Merck Index or anywhere else)

    what is this? (Fluorenol) I can't find it in th Merck Index or online... I'm going to be using it in organic chem and I can't find the info to use in my chemical table.. Is it a combination of fluorene and alchohol? I just looked up fluorene and it said
  100. Science ?

    I was making some instant coffee and it had clumped up...I was heating up some water to go and make coffee... Then I just looked in the container and started to shake the container with the lid off a bit..that is when I knoticed the larger clumps of

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