Post lab questions for chromatography and melting point lab. i have a few ideas of what the answers to these questions should be, but I would like to double check. if anyone can help me, that would be so awesome. Thank you!
Homework Answers
1). Melting point Range is Recorded only when You are heating the capillary tube and solid start melting to the point where it completely melts .
Cooling the capillary after taking melting point will surely not going to determine the correct melting point because melted solid may solidify at low temprature causing alterations.
2) . If the solvent is higher than Starting line than there is full chance that that Your organic compound may dissolve or wash off completely in Solvent system before reaching TLC plate and You will not get Correct Rf values.
3) Covering of Solvent is important to minimise the evaporation of solvent so if the solvent is not covered may be Your solvent evaporate quickly and You will get incorrect Rf values .
4). Since main motive is to calculate RF value which is equal to (Distance travelled by spot of compound / Distance of solvent front ).
Since your sample had crossed the TLC You will not have the Values of Distance travelled by solvent and Rf value cannot be calculated without distance of Solvent travelled.
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Post lab questions for chromatography and melting point lab. i have a few ideas of what the answers to these questions s...
* A student cools a sample in a capillary tube after melting it. Upon attempting to determine the melting point on...
* A student cools a sample in a capillary tube after melting it. Upon attempting to determine the melting point on the same sample, the stjudent does not obtain the same melting point. Why? . A student places his TLC plate in a chamber where the solvent level is higher than the starting line on the TLC. How does that affect the experiment? . A student leaves off the top of her TLC chamber. How will that affect her Rf...
please do two pargraph about this pre lab and lab include Title,purpose ,chemical eqution if their...
please do two pargraph about this pre lab and lab include
Title,purpose ,chemical eqution if their any ،Procedure
,Hazards(hazard Identification,physical and chemical
properties),Experimental Phase, Data
&Observations,Data&Observations cont (melting point and
meling point). and Calcuations
Spinach Laboratory Procedure PROCEDURES Isolation of pigment from leaves: 1. Wash the spinach leaves. Weigh 1.0 g-2.0 g of dry spinach leaves. Remove any stems and veins from the leaves before you weigh. 2. Combine 1.0 g of anhydrous magnesium sulfate with 0.5 g of sand...
3. If the TLC plate development had stopped before the solvent front reached the top of...
3. If the TLC plate development had stopped before the solvent front reached the top of the TLC plate (i.e. maybe it reached the middle of the TLC plate when it was stopped, instead): a) Would the Rf values have been affected? If so, how? If not, why not? Give a numerical example to support your answer. b) Would the size of the spots have been affected? If so, how? If not, why not? (Hint: think about the diffusion of...
Provide a brief rationale for why ( Please help me answer all questions please this is SO important) When benzoic acid is mixed with inorganic sand, what happens to the melting point of the sa...
Provide a brief rationale for why
( Please help me answer all questions please this is SO
important)
When benzoic acid is mixed with inorganic sand, what happens to the melting point of the sample? 6. a. It increases b. It decreases c. It stays the same. d. It increases above the actual melting point then decreases. e. It goes below the eutectic point 7. In thin-layer chromatography, the observed Rr will change upon changing any of the following parameters...
Question 1 5 pts - What is the purpose of melting point? All the answers To...
Question 1 5 pts - What is the purpose of melting point? All the answers To check the purity of solids To check identity of unkown solids To publish for new solids for future characterization Question 2 5 pts How does impurity change melting point value and range? increase-narrowing decrease-narrowing decrease-broadening O increase-broadening Question 3 5 pts What is the reason of an impurity affecting melting point of a solid? Watch Mel. Point Theory video. Not known Obc it weakens...
Question 1 5 pts - What is the purpose of melting point? All the answers To...
Question 1 5 pts - What is the purpose of melting point? All the answers To check the purity of solids To check identity of unkown solids To publish for new solids for future characterization Question 2 5 pts How does impurity change melting point value and range? increase-narrowing decrease-narrowing decrease-broadening O increase-broadening Question 3 5 pts What is the reason of an impurity affecting melting point of a solid? Watch Mel. Point Theory video. Not known Obc it weakens...
30pts total) 1. Irwo known substances have the same melting point as an unknown substance that...
30pts total) 1. Irwo known substances have the same melting point as an unknown substance that you obtained, how could you determine if either of the two known substances is your unknown compound? 2. You are given an impure mix of substances that contains a solid substance, Chemical X, that is soluble in ethanol at all temperatures. You know there is an insoluble impurity in the mix as well as a very soluble impurity, both in ethanol. Can you recrystallize...
Place approximately 10 mg of each of the four reference compounds in labeled vials or 10 X 75-mm ...
can you solve this for me,
please
Place approximately 10 mg of each of the four reference compounds in labeled vials or 10 X 75-mm test tubes and dissolve the samples in a few drops of methanol. In a fifth tube place a quarter of an analgesic tablet and add 1 mL of methanol. Crush the tablet with a rod, stir well, and allow the insoluble material to settle. Note that aspirin is not stable in methanol, so fresh solutions...
Hi can someone help me with my pre lab theory questions (1,2,3) on rate of elution...
Hi can someone help me with my pre lab theory questions (1,2,3)
on rate of elution or Rf? Here is some background below. Please
help explain as many as possible (1-3)! I dont really get the
relation ships in this lab, thank you!
1. What factors affect the rate of elution in organic compounds? 2. Explain what is the relationship between polarities of compounds (polar/non- polar compound) and rate of elution (Rf). 3. Explain what is the relationship between solvent...
Question 5 (0.5 points) A certain compound is spotted on the starting line of a small paper chromatogram and that same compound is spotted again on a much larger paper chromatogram. Both papers...
Question 5 (0.5 points) A certain compound is spotted on the starting line of a small paper chromatogram and that same compound is spotted again on a much larger paper chromatogram. Both papers are developed using the same solvent and are pulled out when the solvent is 2 cm from the top. Which statement is true regarding the R of the spot after development? C) The spot on the larger paper should have a higher Rf because the spot travels...
* A student cools a sample in a capillary tube after melting it. Upon attempting to determine the melting point on the same sample, the stjudent does not obtain the same melting point. Why? . A student places his TLC plate in a chamber where the solvent level is higher than the starting line on the TLC. How does that affect the experiment? . A student leaves off the top of her TLC chamber. How will that affect her Rf...
please do two pargraph about this pre lab and lab include
Title,purpose ,chemical eqution if their any ،Procedure
,Hazards(hazard Identification,physical and chemical
properties),Experimental Phase, Data
&Observations,Data&Observations cont (melting point and
meling point). and Calcuations
Spinach Laboratory Procedure PROCEDURES Isolation of pigment from leaves: 1. Wash the spinach leaves. Weigh 1.0 g-2.0 g of dry spinach leaves. Remove any stems and veins from the leaves before you weigh. 2. Combine 1.0 g of anhydrous magnesium sulfate with 0.5 g of sand...
Provide a brief rationale for why
( Please help me answer all questions please this is SO
important)
When benzoic acid is mixed with inorganic sand, what happens to the melting point of the sample? 6. a. It increases b. It decreases c. It stays the same. d. It increases above the actual melting point then decreases. e. It goes below the eutectic point 7. In thin-layer chromatography, the observed Rr will change upon changing any of the following parameters...
Question 1 5 pts - What is the purpose of melting point? All the answers To check the purity of solids To check identity of unkown solids To publish for new solids for future characterization Question 2 5 pts How does impurity change melting point value and range? increase-narrowing decrease-narrowing decrease-broadening O increase-broadening Question 3 5 pts What is the reason of an impurity affecting melting point of a solid? Watch Mel. Point Theory video. Not known Obc it weakens...
Question 1 5 pts - What is the purpose of melting point? All the answers To check the purity of solids To check identity of unkown solids To publish for new solids for future characterization Question 2 5 pts How does impurity change melting point value and range? increase-narrowing decrease-narrowing decrease-broadening O increase-broadening Question 3 5 pts What is the reason of an impurity affecting melting point of a solid? Watch Mel. Point Theory video. Not known Obc it weakens...
30pts total) 1. Irwo known substances have the same melting point as an unknown substance that you obtained, how could you determine if either of the two known substances is your unknown compound? 2. You are given an impure mix of substances that contains a solid substance, Chemical X, that is soluble in ethanol at all temperatures. You know there is an insoluble impurity in the mix as well as a very soluble impurity, both in ethanol. Can you recrystallize...
can you solve this for me,
please
Place approximately 10 mg of each of the four reference compounds in labeled vials or 10 X 75-mm test tubes and dissolve the samples in a few drops of methanol. In a fifth tube place a quarter of an analgesic tablet and add 1 mL of methanol. Crush the tablet with a rod, stir well, and allow the insoluble material to settle. Note that aspirin is not stable in methanol, so fresh solutions...
Hi can someone help me with my pre lab theory questions (1,2,3)
on rate of elution or Rf? Here is some background below. Please
help explain as many as possible (1-3)! I dont really get the
relation ships in this lab, thank you!
1. What factors affect the rate of elution in organic compounds? 2. Explain what is the relationship between polarities of compounds (polar/non- polar compound) and rate of elution (Rf). 3. Explain what is the relationship between solvent...
Question 5 (0.5 points) A certain compound is spotted on the starting line of a small paper chromatogram and that same compound is spotted again on a much larger paper chromatogram. Both papers are developed using the same solvent and are pulled out when the solvent is 2 cm from the top. Which statement is true regarding the R of the spot after development? C) The spot on the larger paper should have a higher Rf because the spot travels...
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