Which of the following solvent pair definitely cannot be used in a mixed-solvent

Question

Which of the following solvent pair definitely cannot be used in a mixed-solvent recrystallization? acetic acid-water acetone-water ethanol-acetone ethanol-water none of the above (i.e.. all can be used) In recrystallization, addition of too much hot solvent results in less product yield smaller crystal size bigger crystal size faster cooling time none of the above In recrystallization, there were two filtrations done in the procedure. The first filtration involves filtering while solution is hot, while a latter filtration involves filtering when the is already cooled down. The first filtration gets rid of _____ impurities, while the second filtration gets rid of _______ impurities. insoluble impurities; soluble impurities insoluble impurities; insoluble impurities again soluble impurities; insoluble impurities soluble impurities; soluble impurities. both soluble and insoluble impurities; both soluble and insoluble impurities again In recrystallization, why do we cool the first filtrate slowly? to obtain more crystals to obtain bigger crystals to prevent soluble impurities from precipitation to prevent insoluble impurities from precipitation A and B What is occlusion? the amount of supersaturation a solution undergo trapped impurities within the crystal lattice adsorbed impurities on the surfaces of crystal lattice the process in which a solution turns cloudy the phenomenon where a solution fails to recrystallize What is the main reason why impurities are sometimes trapped inside a crystal lattice? cooling the solution too quickly failure to filter using a fluted filter paper failure to wash the crystals with enough cold water leaving the crystals too long in the solution (after the first filtration) diffusion of impurities into the interior of the crystal Why do we wash the desired crystals with cold solvent during the second filtration? to get rid of adsorbed impurities on the surface of the desired crystals to prevent occlusion to obtain bigger crystals to isolate the insoluble impurities to increase product yield Sometimes, crystals do not form in the flask upon cooling of the solution to room temperature. It might be caused by supersaturation. Cooling the solution further might aid precipitation. Name one common technique used to induce the formation of crystals. scratching the glass wall cooling it down more cooling it down faster shaking the flask vigorously swirling the flask gently To the filtrate resulting from the second filtration, sometimes this mother liquor is concentrated more (for example, by boiling off some solvent in it) Why? to remove volatile impurities to get purer crystals to obain smaller crystals to get rid of colored impurities to obtain more product

Explanation / Answer

The answers are:

9. e

10. a

11. c

12. c

Kindly make sure to ask the questions seperately to get the answer of all of them.

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