Homework Answers
Compounds which is hygroscopic will sublime or decompose in the capillary tubes before melting point. Because of this, the exact melting point of the compound cannot be determined. To determine the exact melting point of these compounds open end of the capillary tube must be closed.
Another method can be used where first determine the melting point in usual method then determine in ramp rate of 5 0C.
Ramp rate: Fixed rate of rise in temperature between start and end point in the melting point instrument.
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2. Some compounds sublime in the capillary and some decompose before melting. How do you determine...
* 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...
If you have two compounds that have the same melting point, using melting point determination, how...
If you have two compounds that have the same melting point, using melting point determination, how will you confirm whether the two compounds are the same or different?
Acetylsalicylic acid reacts very, very slowly with water at room temperature and will eventually decompose to...
Acetylsalicylic acid reacts very, very slowly with water at room temperature and will eventually decompose to produce salicylic acid. At temperatures >100oC, this reaction becomes very fast. If your product isn’t completely dry when you attempt to determine melting point, what will happen in the capillary tube? What temperature would you expect for melting point in that situation?
How can you tell that a compound has decomposed on melting and how do impurities affect the melting point of a pure comp...
How can you tell that a compound has decomposed on melting and how do impurities affect the melting point of a pure compound?
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...
When performing a melting point on a solid compound, 2 melting point determinations were made. One...
When performing a melting point on a solid compound, 2 melting point determinations were made. One sample, which was 1 mm in height in the capillary, possessed a melting point of 150-151°C. The other sample was 25 mm in height. What would you expect the approximate melting point to be for this 25 mm sample, if the heating rate for both samples was 2 degrees per minute? (Hint: use algebra to solve the mp range) 4.
You may have noticed that % composition vs Melting Point graphs are given in % Mole...
You may have noticed that % composition vs Melting Point graphs are given in % Mole not 96 Weight. This is because melting point depression is a colligative property (review in your general chemistry text) that depends on the moles of impurity, the same number of moles of impurity of two different compounds will cause the same melting point depression! Before the advent of mass spectrometry this was one of the techniques used to determine the molecular weight of compounds....
How to determine melting point depression (when measuring from the midpoint of melting point ranges). For...
How to determine melting point depression (when measuring from the midpoint of melting point ranges). For example what would be the melting point depression of a component such as benzoic acid with a crude melting point range of (108-124) and a final melting point range of (96-108).
How do you determine if an addition of bromine to trans-stilbene is stereospecific based on the...
How do you determine if an addition of bromine to trans-stilbene is stereospecific based on the melting point of the product from the reaction? How would measuring the optical rotation of the product help identify it?
* 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...
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...
When performing a melting point on a solid compound, 2 melting point determinations were made. One sample, which was 1 mm in height in the capillary, possessed a melting point of 150-151°C. The other sample was 25 mm in height. What would you expect the approximate melting point to be for this 25 mm sample, if the heating rate for both samples was 2 degrees per minute? (Hint: use algebra to solve the mp range) 4.
You may have noticed that % composition vs Melting Point graphs are given in % Mole not 96 Weight. This is because melting point depression is a colligative property (review in your general chemistry text) that depends on the moles of impurity, the same number of moles of impurity of two different compounds will cause the same melting point depression! Before the advent of mass spectrometry this was one of the techniques used to determine the molecular weight of compounds....
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