Thursday
April 24, 2014

Search: Ochem

Number of results: 79

Ochem
balace equation for the follwing 1. Li + O2 2. K + O2 3. Na + O2 4. RbCl + Na
Wednesday, April 22, 2009 at 1:54pm by Lety

ochem
how to determine equivalent hyfrogens in hnmr?
Saturday, December 3, 2011 at 6:05pm by tim

ochem
at room temperature is caffeine soluble in water or dichloromethane
Thursday, October 6, 2011 at 11:36pm by joe

ochem
What's an equation of the hydrolysis of one ester group in tannins by CaCO3?
Thursday, April 15, 2010 at 12:41am by kim

ochem
What's an equation of the hydrolysis of one ester group in tannins by CaCO3?
Friday, April 16, 2010 at 10:30pm by Rachel

ochem
is cis-1,2-dimethylcyclohexane a conformational isomer of trans-1,2-dimethylcycloehexane? Please explain.
Thursday, October 13, 2011 at 9:38pm by sammy

ochem
In a sn2 reaction why do we need sp3 hybrid orbital and not sp2 for the substrate
Sunday, January 29, 2012 at 7:16pm by lou

Ochem
Give two reasons why the crude product in most reactions is not pure.
Saturday, March 10, 2012 at 12:46am by chi

Ochem
Phenacetin has the structure shown below. Write an equation for its preparation starting from 4-ethoxyaniline.
Saturday, March 10, 2012 at 12:45am by chi

Ochem
If 1.43 g of 4-ehoxyaniline and an excess of the acylating agent were used to prepare phencetin, what is the theoretical yield of product?
Saturday, March 10, 2012 at 12:54am by chi

Ochem
What volume of 6.83% (wt./vol.) NaOCl solution is required to oxidize 223 mg of 9-fluorenol to 9-fluorenone? Please help me set this up!
Wednesday, February 1, 2012 at 3:45am by Darby

ochem
For a Grignard reaction, if you start with 3.97 mL of pure bromobenzene and 0.733 g of 1-phenylethanone, what is the theoretical yield of 1,1-diphenylethanol? Please help.
Monday, February 27, 2012 at 1:31am by ochem

ochem
Why is that that a third order alkyl halide reacts faster in SN1 mechanism? Why is it the opposite for SN2? (is it just steric hindrance? )
Monday, November 24, 2008 at 10:11pm by Dora

Ochem Lab
Suggest an appropriate reducing reagents for the following substrates and predict the reaction:(1) 2-hexanone, (2)ethyl 4-nitrobenzoate, (3) hexanal
Sunday, February 8, 2009 at 11:55pm by sady

Ochem
What volume of 6.43% (wt.vol.) NaOCl solution is required to oxidize 221 mg of 9-fluorenol to 9-fluorenone? I'm not to sure of where to start with this problem. Please help!
Wednesday, February 1, 2012 at 12:19am by Jessica

OCHEM
When 2-methyl-2-butene is bubbled into dilute sulfuric acid at room temperature, it appears to dissolve. What new substance has been formed?
Thursday, January 7, 2010 at 6:59pm by josh

ochem
A sample of Limonene has a specific rotation of +76.9. What is the % ee and molecular composition of this sample?
Saturday, November 13, 2010 at 2:38am by bjisa

Ochem
how many grams of NaOCl are in 12.14 mL of a 6.65% (wt./vol.) NaOCl solution? Please help me set this up... I have no idea what to do.
Wednesday, February 1, 2012 at 3:46am by Seerat

OChem
For Extraction using a separatory funnel, what is poured into the funnel first the solution that is to be extracted or the solvent?
Wednesday, June 8, 2011 at 5:53pm by Jasmin

Ochem
Identify the following compound from its IR and proton NMR spectra. C6H10O: NMR: 3.31 (3H, s); 2.41 (1H, s); 1.43 (6H, s) IR: 2110, 3300 cm^-1 (sharp)
Wednesday, February 15, 2012 at 5:10pm by Suzan

ochem
propose structual formulas for pheophytin a and pheophytin b
Monday, November 24, 2008 at 9:21pm by anna

OChem
Why would diethylammonium chloride insoluble in ether? Is the only reason why the salt is insoluble because of polarity, or are there other reasons why? Please explain.
Wednesday, April 27, 2011 at 3:36am by anon

Ochem
By looking at the chemical structures of acetaminophen, aspirin, caffeine, ibuprofen, and naproxin sodium, how are you able to determine the relative polarity of each? Does it have something to do with the symmetry of the structure? Please help!
Tuesday, October 18, 2011 at 4:14am by Luis

OCHEM DR BOB PLEASE HELP!!!!!!!!!1
Why is it possible to use melting point to distinguish the different stereochemistry of the products? (Hint: what is the relationship of the different stereoisomers of the product?)
Wednesday, August 15, 2012 at 2:11pm by JEN

ochem
bromide is a better nucleophile toward the intermediate bromonium ion than ethanol. what product would be obtained if ethanol did carry out this nucleophilic attack?
Saturday, November 29, 2008 at 3:54pm by ana

ochem
Give the reaction products of sodium borohydride (followed by water addition at the end of the reaction) with the following compounds: a) Acetone b) m-nitroacetophenone c) 3-buten-2-one
Tuesday, May 7, 2013 at 11:32pm by ang

ochem
Predict a reasonable melting point of a mixture prepared by combining 25mg of biphenyl (mp=70-71C) with 75mg of acetyl salicylic acid (mp=138-140C). Answer should have temps in it.
Thursday, September 15, 2011 at 12:48am by katie

Ochem
Give the products (if any) expected from the treatment of the following compounds with ozone followed by aqueous hydrogen peroxide. Do not include any byproducts. 1) 2-methyl-2-pentene 2) cyclooctene Please help! I'm not sure on where to start with this problem.
Wednesday, February 8, 2012 at 1:41am by Lucy

ochem
Which of the cyclohexane conformation is more stable? (chair of boat) What factors cause the observed differences in strain energy between the two conformations of the cyclohexane studied above?
Saturday, March 24, 2012 at 3:37pm by cn

ochem
Calculate the amount (volume) of 5.25% (wt./vol.) NaOCl solution (commercial bleach) required to oxidize 100 mg of 9-fluorenol to 9-fluorenone. Whenever appropriate, use balanced chemical equations as a part of your calculation.
Thursday, January 29, 2009 at 9:00pm by steve

OCHEM
How would the 1H NMR spectrum of 1,3-dibenzoylpropane differ from that of the product, trans-1,2-dibenzoylcyclopropane? would the chemical shifts of the protons alpha and beta to the carbonyl groups be appreciably different? explain.
Tuesday, June 1, 2010 at 9:34pm by kris

Ochem
In the reaction between p-aminophenol and acetic anhydride to form acetaminophen, what was the purpose of adding water to the reaction mixture? There are a couple of possible answers, and this requires a detailed explanation for credit. thanks!
Saturday, March 10, 2012 at 12:50am by chi

Ochem
Diethyl ether is used as a solvent for the reaction of diethylamine with m-toluoyl chloride. Why is a solvent necessary for this reaction?
Tuesday, April 26, 2011 at 2:57am by anon

OChem
Anhydrous conditions are vital for a successful Grignard synthesis. To demonstrate this point calculate the mass of the water it would take to destroy the phenylmagnesium bromide you will synthesize. What is he volume of this amount of water? -How exactly do you do this?
Monday, March 2, 2009 at 11:27pm by Kristy

ochem
After reacting racemic phenylethylamine with R,R-tartaric acid, several of our class samples contained needle-like crystals instead of prismatic crystals. What did this indicate about the success of the separation?
Monday, April 2, 2012 at 11:28pm by OH

ochem lab
this deals with TLC chromatography: if 2 compounds have same Rf under identical conditions, does it show that they have identical structures? i think it does. but im not sure why. thanks mucho.
Friday, November 2, 2007 at 4:42pm by christine

ochem
Which of the trans-1,4-dimethylcyclohexane is more stable? ("di-axial" or the "di-equitorial") What factors cause the observed differences in strain energy between the two conformations of trans-1,4-dimethylcyclohexane studied above?
Saturday, March 24, 2012 at 3:39pm by cn

OChem
Anhydrous conditions are vital for a successful Grignard synthesis. To demonstrate this point, calculate the mass of water it would take to destroy the phenylmagnesium bromide that synthesized from 0.48 mL of bromobenzene and 112.5 mg of magnesium. What is the volume of this ...
Sunday, May 17, 2009 at 3:31pm by bee

ochem
If you recrystallize a compound with a 1/2 ethanol/water mixture and water remains in the compound after recrystallization, would that change the melting range of the pure compound?
Tuesday, April 14, 2009 at 6:53pm by bee

Ochem
For the reaction between chloroacetic acid and 4-chlorophenolate to synthesize 4-chlorophenoxyacetic acid, why is this reaction a sn2 reaction?
Saturday, January 15, 2011 at 3:45pm by anon

OChem
1. Why does not fluorene dissolve in 1.5M sodium hydroxide solution? 2. What experimental difficulty would you encounter if you had neclected to include a drying step before evaporating the ether solution of the neutral organic compound (fluorene)?
Tuesday, November 4, 2008 at 4:26pm by James

ochem
A student dissolved 30 mg of a crude unknown in 2 ml of 95% ethanol at room temperature. After chilling in an ice bath and washing crystal with small amount of ice-cold ethanol, she recovered 5mg. Why was the recovery so low?
Wednesday, October 6, 2010 at 3:44am by Anonymous

Ochem Lab
why is it important to spot samples directly on the marks made on the TLC plate? This is for Thin Layer Chromotography. Is this important so that the solvents move directly up the plate and can be identifies easily? Thanks
Sunday, October 24, 2010 at 6:25pm by Adam

OCHEM
Write the mechanism for (E)-2-5-dimethyl-hex-3-ene and bromine? Assign the R, S configuration for each of the products and determine the stereochemical relationship of each set of products. I think the products will be trans but I am not quite sure how the mechanism work. Any ...
Monday, February 1, 2010 at 6:56pm by Rebecca

ochem lab
What is the expected observed rotation of a 9.1 x 10-5 M solution of compound X? Note: compound X has a specific rotation of [α]D20 = -49o and a molecular weight of 235.2 g/mol. In addition, the path length of the cell used to take the polarimetry measurement was 5.0 cm.
Monday, April 2, 2012 at 11:28pm by cn

Ochem
Which Alkene is capable of stereoisomerism: 1-pentene, 2-methyl-1-pentene, 2-methyl-2-pentene, 2-pentene, or 2,3-dimethyl-2-butene?
Saturday, July 21, 2012 at 6:16pm by Michele

OCHem
The amount of methylcycloheane with the substituent in the equatorial orientation at room temperature (25C) would be The Gibbs free energy for axial methyl to equatorial methyl is -7.28Kj/mol (the universal gas constant is 8.314 j/deg-mol). I cant remember how to solve this...
Friday, December 10, 2010 at 1:15pm by Alex

OChem
Could someone explain these two reaction mechanisms (I know they are substitution): 1) 1-propanol reacted with H2SO4 and NaBr 2) 2-pentanol reacted with H2SO4 and NaBr does the carbocation rearrange for the second reaction? thanks for the help!
Tuesday, April 21, 2009 at 10:13pm by bee

OChem
A mixture of acetone and ethyl acetate of unknown ratio begins to boil at 65 degrees celcius (760 torr). What is the composition of this binary mixture in terms of the mole fraction of acetone and that of ethyl acetate?
Saturday, September 25, 2010 at 9:30pm by doug

OChem
Confused! Please help!! Assume an organic compound has a partition coefficient between water and diethyl ether equal to 6.63. If there are initially 9.05 grams of the compound dissolved in 80.0 mL of water, how many grams will remain in the aqueous layer after extraction with ...
Sunday, October 2, 2011 at 4:30am by Katherine

ochem
Rank fastest to slowest reaction with HBr: A) H3C-C---C-CH3 (alkyne; that's a triple bond between the carbons) B) H CH3 (alkene; trans) = H3C H C) H3C CH3 (alkene; 3 methyl substituents) = H3C H Please explain why. Thanks!
Monday, April 27, 2009 at 11:59pm by bee

ochem
Can you suggest some possible reasons for using a mixture of water and ethanol (1:1 mixture H2O/EtOH) as crystallizing solvent rather than using either pure ethanol or pure water?
Friday, January 23, 2009 at 12:43am by lili

OChem
What's the purpose of "PREPARATION OF A SYNTHETIC PLANT HORMONE Adapted from "p-Chlorophenoxyacetic Acid Preparation of a Synthetic Plant Hormone." thanks
Thursday, April 8, 2010 at 3:35am by mina

ochem
Consider a sample that is a mixture composed of biphenyl, benzoic acid, and benzyl alcohol. Predict the order of elution of the components in this mixture on the TLC plate when solvent system a, b or c is used. a)Cyclohexane: Methylenechloride:100%:0% b)Cyclohexane: ...
Tuesday, May 7, 2013 at 11:25pm by bez

ochem
A sample of Limonene has a specific rotation of +76.9. What is the % ee and molecular composition of this sample? R(+)- is +125.6 and S (-)- 122.1. I'm confused I don't know whether I should divided by 125.6 or 122.1. %ee=(76.9/125.6)*100=61%. Is this correct? I'm clueless as ...
Saturday, November 13, 2010 at 2:42am by bjisa

ochem
when the concentration of CHBr3 and NaOH are both .145, the rate of the reaction is .0040 M/s. What is the rate of the eaction if the concentration of CHBr3 is doubled?if the conc. is halved?if the two conc. are both increased by a factor of five? CH3Br+NaOH-->CH3OH+NaBr
Saturday, November 13, 2010 at 5:03am by natalie

ochem
when the concentration of CHBr3 and NaOH are both .145, the rate of the reaction is .0040 M/s. What is the rate of the eaction if the concentration of CHBr3 is doubled?if the conc. is halved?if the two conc. are both increased by a factor of five? CH3Br+NaOH-->CH3OH+NaBr
Sunday, November 14, 2010 at 3:59am by natalie

OChem
What intermolecular forces are important in the binding of organic molecules to the absorbent in absorption chromatogrpahy? Select all that apply. A) London forces B) Van der Waals forces C) Covalent Bonding D) Hydrogen bonding E) Dipole-dipole interactions F) Lewis acid-base ...
Wednesday, October 12, 2011 at 3:44am by Allison

Ochem
If you start with 2.97 g of zest and obtain 459 mg of pure limonene, what is your percent recovery? I was thinking of dividing .459g by 2.97g and then multiplying by 100 to get the percent recovery. But then I realized that the zest and limonene aren't the same. So how would I...
Wednesday, November 2, 2011 at 4:14pm by Lucille

OChem
If the limonene reactant described in question 2 is composed of a single enantiomer, how many stereoisomers of the product will be formed in the reaction? If there are more than one stereoisomers what would their relationship be? Question 2: Suppose a student is measuring the ...
Sunday, February 13, 2011 at 9:09pm by Kaval

OChem
What does it mean for a conformation to be more stage than another conformation in terms of the strain energy? Based on your answer, which of the above conformations of n-butane (eclipsed, gauche, anti) is more stable? What factors cause the observed differences in strain ...
Saturday, March 24, 2012 at 3:36pm by cn

OChem
Calculate the amount (volume) of 5.25% (wt./vol.) NaOCl solution (commercial bleach) required to oxidize 100 mg of 9-fluorenol to 9-fluorenone. Whenever appropriate, use balanced chemical equations as a part of your calculation. I know that I need to start off with the ...
Tuesday, December 22, 2009 at 12:36am by Sarah

OCHEM
A student needed to determine the percent composition of a mixture that contained fluorene and benzoic acid. The student took 245 mg of the mixture and used the extraction method to separate the components. Then both compounds were recrystallized and dried. The experiment ...
Sunday, August 12, 2012 at 12:43am by Jen

ochem
list from strongest acid to weakest acid HC(triple bond)CCH3 H2C=CH2 H3CNH2 CH4 H2O i thought the order went HC(triple)CCH3 H3CNH2 H2O H2C=CH2 CH4 but it comes out as wrong and i dont know why >
Monday, February 14, 2011 at 2:32am by Allie

OChem
1. if and when boiling points can be used to determine the purity of organic compounds. 2. if and when boiling points can be used to identify organic compounds. 3. when can fractional distillation be used to separate organic compounds
Sunday, September 23, 2012 at 6:31pm by Mia

OChem
A mixture of fluorene and benzoic acid is dissolved in diethyl ether and mixed thoroughly with an aqueous solution of NaOH. After the layers separate, what will each of the layers contain? Label the layers. Indicate the main components, not species that could be present in ...
Thursday, October 20, 2011 at 1:26am by David

Ochem
What is the purpose of refluxing? Which reaction conditions are indicated with reflux? Will you apply heat? How do you know the temperature at which you should reflux? I think it is "A reflux system is used to condense vapours escaping from the hot flask. " Please help. Your ...
Wednesday, July 5, 2006 at 11:10pm by Jay

Chemistry/ OChem
Each of the solvents given should effectively separate of the following mixtures by TLC. Match the appropriate solvent with the mixture that you would expect to separate well with the solvent. Select your solvent from the following: hexane, methylene chloride, or acetone. (a) ...
Thursday, October 9, 2008 at 3:22pm by Neets

OChem
A solution consisting of water and ethanol is found to have a refractive index of 1.3541 at 20 degrees C. The refractive indices at 20 degrees C of water and ethanol are 1.3330 and 1.3610, respectively. Determine the molar composition (in percent) of the mixture by assuming a ...
Wednesday, October 26, 2011 at 12:53am by Omar

Ochem
What would be a newer more efficient method to do the qualitative analysis of an unknown. I am trying to find a good method and asses its greenness (Green chemistry) and say why it better than the common method used. please help as soon as possible. This is such an open ended ...
Tuesday, June 20, 2006 at 11:36am by Jamshid

ochem
You have a mixture composed of 90% benzoic acid and 10% naphthalene. Benzoic acid has a melting point of 122.4 oC, while naphthalene has a melting point of 80.2 oC. You can say with certainty that the melting point of the mixture will be: A. greater than any of the two melting...
Monday, October 5, 2009 at 7:10pm by jamees

Ochem
A student needed to determine the percent composition of a mixture that contained fluorene and benzoic acid. The student took 283 mg of the mixture and used the extraction method to separate the components. Then both compounds were recrystallized and dried. The experiment ...
Wednesday, October 19, 2011 at 6:53pm by Lindsay

Chemistry/ OChem
Consider the following errors that could be made when running TLC. Indicate what should be done to correct the error. a) a two-component mixture containing 1-octene and 1,4-dimethylbenzene gave only one spot with an Rf value of .95. The solvent uses was acetone. b) a two-...
Thursday, October 9, 2008 at 3:28pm by Neets

OCHEM
What would be the effect of decrease the carrier gas flow rate, raise the column temp, have on the retention time? What would be the effect of raise the column temp and decrease the carrier gas flow rate on the ability to resolve two closely spaced peaks? For the first ...
Tuesday, December 22, 2009 at 10:22pm by Sarah

OChem
A sample of limonene has a specific rotation of +81.5. (Given that R-(+)-limonene = +125.5 and, S-(-)-limonene = -122.1). What is the %ee? ______%ee What is the molecular composition of this same sample? S isomer = ______% R isomer = ______% This is how I solved for the R and ...
Wednesday, November 2, 2011 at 7:35pm by Susie

ochem
Calcualte how many milliliters of carbon dioxide would be produced theoretically from 20g of sucrose of 25 degree C and 1 atmosphere pressure. I can use the formula PV=nRT 20g C12H22O11 * moles sucrose/342.3g suc. that would equal: .0584 moles. But what next. The experiment ...
Monday, October 9, 2006 at 10:46pm by tesla

OChem Nomenclature
Here is a compound that I am trying to name... H H \ / C || CH3-CH2-C-CH2-CH2-CH2-CH3 I came up with 3-methylheptene, but the answer says 2-ethyl-1-hexene. Can someone please explain why I'm wrong? Thanks that showed up wrong - the methyl with the double bond should be on that...
Wednesday, June 13, 2007 at 11:30pm by Lacey

ochem 2
1. Below are the IR and 1H NMR spectra for a compound with the molecular formula of C11H16O. List all the possible information coming from each spectra, and then use this to elucidate the structure from the possible compounds shown. Briefly explain your rationale. IR spectra...
Sunday, December 2, 2012 at 2:06am by Ankita

Ochem
The following question is due to a reaction in organic chemistry ethanol from sucrose. I did not properly state in my last post where the reaction came from. I apologize for this (Dr.Bob). I repost the same question: Calculate how many milliliters of carbon dioxide would be ...
Thursday, October 12, 2006 at 10:35am by tesla

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