1. College Chemistry

    a mixture contains two crystalline solid X and Y. Decide if pure X can be obtained by a proper recrystallization using solvent A. Include the exact volumes of solvent used and the amount of pure X obtained. GIVEN: Solubility of X in boiling A :200mg/ml
  2. Orgo Lab

    Recrystallization is often used at the end of a synthesis. Choose the most accurate answer/s to explain the purpose of recrystallization and how it is done effectively? Note there may be more than one correct answer. 1.Dissolve the crude product in the
  3. chemistry

    1. You are given a mixture containing two compounds, A and B. Both compounds have a solubility of 1 g/ 100 mL of solvent at 20 °C and 16 g/ 100 mL of solvent at 100 °C. The sample is composed of 3.5 g of A and 10 g of B. At 100 °C the entire sample just
  4. Organic Chemistry

    Which statements are FALSE about selecting a solvent for recrystallization? (Select all correct answers.) Any solvent can be used for recrystallization as long as the compound dissolves in it. The compound should exhibit a high solubility in the solvent at
  5. Low recovery

    The question is: A student performs a crystallization on an impure sample of biphenyl. The sample weighs 0.5g and contains about 5% impurity. Using his knowledge of solubility, he decides to use benzene as a solvent. The final weight is only 0.02g. Why is
  6. Chem

    Which of the following results from the presence of a solute in a given solvent? A. The vapor pressure of the solution is lower than that of the pure solvent. B. The boiling point of the solution is lower than that of the pure solvent. C. The freezing
  7. Chemistry

    Which of the following results from the presence of a solute in a given solvent? A. The vapor pressure of the solution is lower than that of the pure solvent. B. The boiling point of the solution is lower than that of the pure solvent. C. The freezing
  8. organic chemistry

    which of the 3 solvent would not be suitable recrystallization solvent for acetanilide? Why? - water as recrytallization solvent for acetanilide - chloroform as recrystallization solvent for acxetanilide - methanol as recrystallization solvent for
  9. chemistry ap

    Why would [23.8-(.0588)(23.8)] be the proper setup to determine the vapor pressure of a solution at 25 Celsius that has 45g of C6H12O6, glucose (MM=180gxmol^-1), dissolved in 72g of H2O? The vapor pressure of pure water at 25Celsius is 23.8 torr. vp pure
  10. Organic Chem

    A 20 g mixture containing 95% (by weight) of A and 5% of B is recrystallized in toluene (b.p. 110 C). Solubility for compound A is 1.5 g @20 degrees and 10 g @ 110 degrees. For compound B solubility is 0.5 g @20 degrees and 8 g @ 110 degrees. What amount
  11. Organic Chemistry

    What are the advantages of using a solvent pair for recrystallization? Select all that apply. A) You can control the solubility of the substance in the mixed solvent. B) You don't have to know the exact amounts of the solvents needed. C) You can quickly
  12. CHEMISTRY

    The solubility of barium sulfate varies with the composition of the solvent. In which one of the solvent mixtures below would BaSO4 have the lowest solubility? i)1.0 M (NH4)2SO4(aq), ii) 0.10 M Na2SO4(aq), iii) pure water, iv) 1.0 M HCl(aq) v) 0.5 M
  13. chemistry

    help please, have no clue how to solve this. (a) you are given a mixture containing two compounds, A and B. both compounds have a solubility of 1g/100mL of solvent at 20 deg C and 16g/100mL of solvent at 100 deg C. The sample is composed of 3.5 g of A and
  14. To Sheryl: polarity

    The exact question is: Benzyl alcohol (bp 205 degree C) was selected by a student to crystallize fluorenol (mp 153-154 degrees C) because the solubility characteristics of this solvent are appropriate. However, this solvent is not a good choice. Explain.
  15. ORG CHEM LAB

    Im doing a conclusion on a lab of acetaminophen. We were to take a melting point of the crude smale of acetaminophen and melting point of the crystallized acetaminophen. The mp for crude sample: 169.2 degree C The mp for crystallized sample: 172. degree C
  16. Organic Chemistry

    In order to obtain pure synthetic plant hormone, a 2:1 mixture of water and ethanol is used as the crystallizing solvent. Why is a solvent mixture used? A. Organic compounds are not soluble in pure ethanol. B. Ethanol and water have similar boiling points,
  17. Organic Chemistry

    Referring to solvent mixtures, which statements are TRUE ? (Select all correct answers.) The solvents of the solvent mixture should have very similar polarities. The solvents of the solvent mixture should have different polarities. The student has to pay
  18. Organic CHEM

    What is the whole point of using solvent pairs for recrystallization(say a mix of ethanol and water) rather than just using one or the other? -I know that you use solvent pairs when you solute won't dissolve in either pure water or pure ethanol, but then
  19. chemistry

    Assume the density of aqueous HCl is the same as water (1.0 g/mL) and use the densities of ethanol (0.789 g/mL) and water as well as the actual amount of recrystallization solvent used to calculate the mass of recrystallization solvent.
  20. Chemistry

    A student determined that ethanol was the best solvent to use for a recrystallization based on small scale trials. When the recrystallization was carried out on a larger scale, no crystals were obtained on cooling the hot solution. Why? and how would you
  21. Chemistry repost

    A student determined that ethanol was the best solvent to use for a recrystallization based on small scale trials. When the recrystallization was carried out on a larger scale, no crystals were obtained on cooling the hot solution. Why? and how would you
  22. Organic Chemistry

    The separation of a mixture of benzoic acid and benzoin in dichloromethane into its pure compounds by a combination of solvent extraction , distillation and recrystallization. Why is carbon dioxide evolved when the organic solution is shaken with sodium
  23. 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?
  24. chemistry

    According to Raoult's law, which statement is false? a. The vapor pressure of a solvent over a solution decreases as its mole fraction increases. b. The solubility of a gas increases as the temperature decreases. c. The vapor pressure of a solvent over a
  25. organic chemistry

    if you were not told which solvent to use in the recrystallization experiment, how would you determine a suitable recrystallization solvent ?
  26. Chemistry

    I am reading through material for a recrystallization experiment, and I had a few things I wasn't sure about; - Why once filtered, should the recrystallization solution be allowed to cool slowly, undisturbed, rather than quickly? and -What makes a good
  27. Chemistry

    The melting point of a pure solvent (kf=1.79°C/m) is -116.3°C. If 312 g of an ionic solid (i=2.6) is added to 567.7 g of the solvent, the new melting point is -101.6°C. What is the molar mass of the ionic solute?
  28. Chemistry

    Aspirin can be prepared by the reaction of salicylic acid with an excess of acetic anhydride, using phosphoric acid as a catalyst. Once the aspirin is formed, it is precipitated from the reaction mixture by adding water and filtering. The solid aspirin
  29. chem

    a.What advantages does ligroin have over n-pentane as a recrystallization solvent? b. What advantages foes ethanol have over n-octanol as a recrystallization solvent?
  30. Chem

    the solubility of a compound is 59g per 100 mL in boiling methanol and 30g per 100mL in cold methanol, whereas its solubility in water is 7.2g per 100 mL at 95 C and .22g per 100mL at 2C. Which solvent would be better for recrystallization of the compound?
  31. Solvent temp

    Question: A student dissolved 0.30 g of a crude product in 10.5mL (the minimum amount required) ethanol at 25 degrees C. He cooled the solution in an ice-water bath for 15 minutes and obtained beautiful crystals. He filtered the crystals on a Hirsch funnel
  32. chem 121

    explain why washing an impure solid with a cold solvent is not good as recrystallization for removing all the soluble impurities? why is the final product from a recrystallization isolated by a suction rather than gravity filtration?
  33. SCIENCE

    (aq) means the solution is dissolved in water used as a solvent. (l) means the COMPOUND (not element, usually) is a pure liquid. (g) means gas and (s) means solid. In the equation below, HCl(aq) + NaOH(aq) -->NaCl(aq) + H2O(l)This means that an aqueous
  34. 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?
  35. 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
  36. Chem

    To purify acetanilide by a recrystallization procedure. a) Describe how you would decide what solvent to use in order to accomplish this objective. b) How you would calculate the effeciency of your recrystallization procedure with respect to; ---
  37. Chemistry

    WHat are the structural formulas for glycerin, hexane, and ethanol. Do these structural formaulas support the solubility data obtained?? It is almost impossible to draw structural formulas on the computer. In line formulas may help. But you need to refine
  38. Chemistry

    For the Following sets of compounds determine the best solvent, by looking at structure, also by looking at solubility vs. temp. Which is the best solvent for crystalization, in which the compound is too soluble, and in which solvent the compound is not
  39. 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
  40. Difference?

    What is the difference between these two questions? They look the same to me, like they're asking the same thing. Not likely. Question: A student spots an unknown sample on a TLC plate and develops it in dichloromethane solvent. Only one spot, for which
  41. Gen Chem

    Which of the following conditions MUST be true for the entropy of a pure solid to be zero? a) T must be 0 K b) The solid must be crystalline and not amorphous c)the solid must be perfectly ordered d) the solid form must be an element
  42. Chemistry

    The solubility of compound A in ethanol is 0.4 g per 100 mL at 0C and 5.0 g per 100 mL at 78C. What is the minimum amount of solvent needed to recrystallize an 8.0 g sample of compound A? How much would be lost in the recrystallization? Show your work.
  43. CHEM HELP

    The partial pressure of water above a solution of water and a nonvolatile solute at 25oC is 19.2 mm Hg. What is the mole fraction of the solute please help....I really don't know how I am supposed to solve this question. I know that Partial pressure of the
  44. Chemistry

    1. What is the minimum volume of hot water needed to dissolve 0.200g phenacetin? How much phenacetin will remain in that volume of water once it cools? 2. Why is it important that all the solid dissolves in the hot solvent, before the solution is cooled?
  45. Chemistry

    Tooth enamel is made up of hydroxyapatite, Ca_10(PO_4)_6(OH)_2 or the empirical formula, Ca_5(PO_4)_3(OH). Use the empirical formula for all calculations because stoichiometry plays two significant roles. A. Print the balanced chemical equation for the
  46. organic chemistry

    what could be possible answers to these two questions.....1 why determine the amount of solvent by difference and not by weighing the final distillate????? why not distill off all the solvent at the very beginnig and then separate the solid residue of
  47. 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
  48. chemistry

    Suggest a solvent pair for N-Bromosuccinimide using the following solubility data. Solubility of N-Bromosuccinimide (g/100g of solvent) Tert-butanol 0.73 Hexane 0.006 Glacial acetic acid 3.10 Acetone 14.40 Carbon tetrachloride 0.02
  49. Chemistry

    If we wish to find the molar mass of a pure solid organic compound, which measurement would be most useful and why? A)melting point of the solid B)melting point depression of the mixture of the solid with 1,4-dichlorobenzene C)Heat of combustion
  50. chemistry chem check

    an ideal mixture contains 0.4 mol of nonvolatile solute and 0.8 mol of volatile solvent. the resulting vapor pressure was 60 mmHg at 300K. What vapor pressure should be reported at 300 K for pure solvent? A) 48 mmHg B) 60 mmHg C) 75 mmHg D) 90 mmHg **Would
  51. lab report

    why not distill off all the solvent first then separate the solid residue of benzoin and benzoic acid by recrystallization
  52. chem

    The solvent for an organic reaction is prepared by mixing 50.0 of acetone () with 57.0 of ethyl acetate (). This mixture is stored at 25.0 . The vapor pressure and the densities for the two pure components at 25.0 are given in the following table. What is
  53. Orgo

    The solubility of compound A in ethanol is .8g per 100ml at 0degreesC and 5.0g per 100ml at 78degreesC. What is the minimum amount of ethanol needed to recrystallize a 12.0g sample of compound A? How much would be lost in the recrystallization, that is,
  54. AP Chemistry

    A 25.0g sample of glucose, C6H12O6, dissolves in 525mL of distilled water. a. what is the boiling point elevation of the solution over the pure solvent? b. At what temperature will the solution boil at sea level? --- I'm not a fan of these types of
  55. Sample purity

    Question: A student spots an unknown sample on a TLC plate and develops it in pentane solvent. Only one spot, for which the Rf value is 0.05, is observed. Is the unknown a pure compound? What can be done to verify the purity of the sample using TLC? My
  56. Chemistry please check

    1. An ionic compound solution is a(an)________ of electric current. non-conductor absorber emitter good conductor reverser ans: good conductor 2. Hydrogen bonding in water accounts for water's higher than expected boiling temperature the fact that ice
  57. math

    A chemist has 80 pints of a 20% iodine solution. How many pints of iodine must be added to produce a solution that is 33.1/3% iodine? Please help me work this through Let X be the number of pints of iodine that must be added. You start out with a mix that
  58. chemistry

    Can anyone help me with this question. Propose a method in detail to determine the concentration of two components, quinine and anthracene in a mixture using fluorimetry. You have access to pure sulutes and an appropriate solvent. The excitation and
  59. weighted averages

    How do you do this? a pineapple drink contains 15% pineapple juice. how much pure pineapple juice should be added to 8 quarts of the drink to obtain a mixture containing 50% pineapple juice? Let X be the amount of pure pineapple that you must add, in
  60. ap chemistry

    glycerin C3H8O is a nonvolatile liquid. what is the vapor pressure of a solution made by adding 164 g of glycerin to 338 mL of H2O at 39.8C. The vapor pressure of pure water at 39.8C is 54.74 torr and its density is 0.992 g/cm3 P solution= X solvent p
  61. Chemistry

    If the freezing point of a pure solvent is 6.00 degrees Celsius, will the solvent which is contaminated with a soluble material have a freezing point (higher than, lower than or same as) 6.00 degrees Celsius? Explain.
  62. chem lab (webwork)

    Which of the following is NOT true of colligative properties? Colligative properties are... A. dependent on the mass of solute present. B. independent of the chemical identity of the solute. C. responsible for lowering the vapor pressure of a solution
  63. Chemistry

    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
  64. Chemistry

    When 0.855 g of this solid was dissolved in 7.50 g of napthalene, the solution had a freezing point of 78.0° C. The pure solvent freezes at 80.0° C; its molal freezing point constant is 6.8° C/m. What is the molecular formula of the compound?
  65. chemistry

    At 25 degrees Celsius the vapour pressure of pure benzene is 93.9 torr. When nonvolatile solvent is dissolved in benzene, the vapour pressure of benzene is lowered to 91.5 torr. What are the concerntration of solute and solvent expressed in mole fractions
  66. chemistry

    Which of the solvents will be most effective at dissolving a nonpolar gas like methane? water, a polar solvent solid mercury hexane, a nonpolar solvent solid copper is it a?
  67. Organic Chem.

    When a tlc plate was developed the solvent front ran off the top of the plate, why? A two component mixture containing a dicarboxylic acid and tricarboxylic acid gave only one spot with an Rf value of 0.05. Solvent used; hexane. What went wrong? Solvent
  68. Chemistry

    The equation for lowering the freezing point of a solvent is given in your manual. Given that the freezing point for the pure solvent is 79.4 °C , the molality is 0.1 m , and the freezing point depression constant is 6.9 °C/m , determine the freezing
  69. chemistry

    Kc = [Na+][Cl-]/[NaCl(s)] The above equation contains the concentration of NaCl in solid NaCl. This concentration is related to the density of solid NaCl and its molar mass. Since the density of NaCl or of any pure solid or pure liquid does not vary with
  70. Organic Chemistry

    Q: Each of the solvent given should effectively separate one of the following mixtures by thin-layer chromatography. Match the appropriate solvent with the mixture that you would expect to separate well with that solvent. Select your solvent from the
  71. Organic Chem

    Q: Each of the solvent given should effectively separate one of the following mixtures by thin-layer chromatography. Match the appropriate solvent with the mixture that you would expect to separate well with that solvent. Select your solvent from the
  72. Organic Chemistry

    Compound A is recrystallized from n-propanol. Given are the following solubilities (in 100 mL of solvent): 160 g/100 °C, 100 g/80 °C, 60 g/60 °C, 20 g/20 °C, 15 g/10 °C and 10 g/0 °C. How many milliliters of solvent are needed to dissolve 80.0 g of
  73. Chemistry

    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
  74. chemistry

    explain why the pure solvent shows a level horizontal curve as solidification occurs, but the curve for the solution slopes downward slightly. The solvent is BHT and the added particles are an unknown compound. My reasoning is that it happens because the
  75. Math

    A 16 ounce container of a solvent must be mixed with 48 ounces of water. What fraction of solvent is there in the total mixture (lowest terms)?
  76. Chemistry

    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
  77. Organic Chemistry

    The solubility of a compound is 59g per 100mL in boiling methanol and 30g per 100mL in cold methanol, whereas its solubility in water is 7.2g per 100mL at 95C and 0.22g per 100mL at 2C. Which solvent would be better for recrystallization of the compound?
  78. 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
  79. chem

    Determine the mass(w/w%) percent of CaCl2 given the following information. The vapor pressure of a CaCl2 solution is 81.6 mmHg at 50degrees C. The vapor pressure of pure water at this temp is 92.6mmHg. Assume that you have 1.00mol of water.[Raoult's Law:
  80. Math

    A 16 ounce container of a solvent must be mixed with 48 ounces of water. What fraction of solvent is there in the total mixture (lowest terms)? equals 16/64= 1/4
  81. ap chem

    Find the molecular mass of a solute by freezing point depression. Solvent: para-dichlorobenzene Freezing point of pure solvent: 53.02C Mass of unknown substance: 2.04g Freezingpointdepressin constant:7.1c/m Mass of para-dichlo...: 24.80g Freexing point
  82. Chemistry

    The solubility of insoluble substances changes depending on the nature of the solution. Below are two solutions in which copper (II) hydroxide is dissolved; in each case, the solubility is not the same as it is in pure water. a. For each solution state
  83. college algebra word problem

    A goldsmith has two alloys that are different purities of gold. The first is 3/4 pure and the second is 5/12 pure. How many ounces of each should be melted and mixed in order to obtain a 6 oz mixture that is 2/3 pure gold?
  84. chemistry

    Describe the circumstances in which the following processes could be used to separate the components of a mixture. -sublimation -crystallization -evaporation of a solvent from a solution -dissolving of an impure substance in a solvent
  85. AP Chemistry

    Will a non-volatile solute always lower the vapor pressure of the pure solvent in solution? Why or why not?
  86. chemistry

    The vapor pressure of pure water at 70°C is 231 mm Hg. What is the vapor pressure depression of a solution of 115 g of the antifreeze ethylene glycol, C2H6O2, a nonvolatile compound, in 205 g of water? Use molar masses with at least as many significant
  87. chem

    Suppose you need to extract an organic substance S from water into ether, where the distribution constant Kdist = [S]org/[S]aq is at first unknown. a) By testing the solubility of the material in each solvent under saturating conditions at room
  88. Chemistry

    43. List and describe three factors that influence solubility: (Source-wikipedia) The solubility of a given solute in a given solvent typically depends on temperature. For many solids dissolved in liquid water, the solubility increases with temperature up
  89. chemistry

    A solution of 0.2113 g of water dissolved in 25.0 g of a solvent freezes at 11.5 °C below the freezing point of the solvent. What is Kf for this solvent?
  90. chemistry

    A solution of 0.2113 g of water dissolved in 25.0 g of a solvent freezes at 11.5 °C below the freezing point of the solvent. What is Kf for this solvent?
  91. chm

    How would you classify the following material?swimming pool water homogeneous mixture<<< heterogeneous mixture a pure element a pure compound depends on how many children have been in it
  92. Chemistry

    A student needs to analyze a mixture containing an alcohol and a ketone by silica gel tlc. Consult the table of solvent polarities above and suggest a likely developing solvent. Explain
  93. Chemistry

    During fractional distillation of ethanol/water mixture, why can't pure ethanol be obtained (i.e. distillated contains a little water)?
  94. Chemistry

    a solution of 0.2113 g of water dissolv ed in 25g of a solvent freezes at 11.5 degrees celcius below the freezing point of the solvent. what is the Kf for the solvent? A)0.735 B)1.36 c)5.39 D)24.5 Help!!! delta T = Kf*molality Calculate molality = #mols
  95. organic chem

    Suppose you need to extract an organic substance S from water into ether, where the distribution constant Kdist = [S]org/[S]aq is at first unknown. a) By testing the solubility of the material in each solvent under saturating conditions at room
  96. TLC purity

    Question: A student spots an unknown sample on a TLC plate and develops it in dichloromethane solvent. Only one spot, for which the Rf value is 0.95, is observed. Does this indicate that the unknown material is a pure compound? What can be done to verify
  97. Sciences

    What is a substance that cannot be separated into simpler substances by physical or mechanical methods such as filtering, boiling, or sifting? A crystalline solid A sublimation A pure substance •• An amorphous solid Correct me if I'm wrong
  98. chemistry

    Nitrogen dioxide (NO2) cannot be obtained in a pure form in the gas phase because it exists as a mixture of NO2 and N2O4. At 23°C and 0.94 atm, the density of this gas mixture is 2.6 g/L. What is the partial pressure of each gas? NO2 N2O4
  99. Chemistry

    The solubility of insoluble substances changes depending on the nature of the solution. Below are two solutions in which Cu(OH)2 is dissolved; in each case, the solubility of Cu(OH)2 in those solutions is not the same as it is in pure water. (a) For each
  100. Organic Chemistry

    Assuming you have a mixture of 2-nitrophenol and 4-nitrophenol, which solvent would be most suitable for recrystallization if you want to isolate 4-nitrophenol? Water Diethyl ether Toluene Acetone Ethanol