please help me answer question from number 2(melring point) and 3(recrystalizati
ID: 693996 • Letter: P
Question
please help me answer question from number 2(melring point) and 3(recrystalization)
Punctional groups >like alcohols, carboxylic acids, esters, amines, amides, etc. u. rewnah projection. 2. Melting Points What is the purpose of a melting point determination? If the melting point range is short (2 degrees or less) what significance does this have? What is the significance of a broad mp range? What if the mp range of a compound is short, but not very close to the expected mp temperature? If a solid is not dry, what effect does this have on the melting point determination? a. b. How can a known compound be used to determine the identity of an unknown compound using melting point data? 3. Recrystallization a. What happens during recrystallization? What is the purpose of recrystallizing a product or isolated material? b. What is the purpose of boiling stones? Why should you use them? c. How is a solvent chosen for recrystallization? d. How were melting points used in experiments? e. How is percent recovery calculated? 4. Extraction What is an extraction? How can extraction be used to separate acidic, basic, and neutralExplanation / Answer
2.a ) Purpose of melting point determination:
1. Melting point is one of the most important physical characteristics of solids
2. To check whether the solids are pure or not.
If melting point range is too short it signifies that experimental error is less and the compound is pure.
Broad melting point range signifies large experimental error or there are impurities in the sample.
If the melting point range is too short but not very close to melting point temperature: the compound is not similar to that of the known compound.
If the solid is not dry, then the experimental melting point is more than the exact one.
b) The melting points of known compounds are known
If the melting point of unknown compound matches with any of the known compounds, then we can conclude the identity of the unknown with the known one.
2. a) Recrystallisation is the process of crystallisaing out a solid from a particular solvent. The solid is obtained as crystals.
Purpose: To purify a solid compound and to know the exact structure from X-ray crystallography.
b) Boiling chips are used to boil the distilling solvents more gently.
If the boiling solvent is over heated, then there is possibility of bumping. To avoid it, boiling chips are used.
c) For recrystallistaion: a solvent is chosen in which the compound is not very much soluble. Then the sample is dissolved in minimum volume of hot solvent and the mixture is cooled down slowly to crystallise out the compound.
d) Melting points are used to determine the identity of compounds.
e) Percent recovery = (experimental yield * 100)/ (theoretical yield) %
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.