Given the following solvents: Dichloromethane, hexane, toluene, methanol, acetone, water and acetic acid. Which of the following solvent pairs are immiscible?
a) Dichloromethane-hexane
b) Hexane-water
c) Dichloromethane-toluene
d) Acetone-acetic acid
7. The technique that is used for solid substance purification
a) Distillation
b) TLC
c) Extraction
d) Recrystallization
8. Which of the following pairs of solvents would you recommend for extraction of a compound A?
a) Dichloromethane- water (K = 2.5)
b) Hexane - water (K = 6)
c) Ether -water (K = 2)
d) Ethyl acetate-water (K = 10)
9. The main step of recrystallization process is
a) Dissolve the solid in large amount of cooled solvent
b) Take the melting point of wet solid
c) Cool the hot solution slowly
d) Filter the hot solution to remove all soluble impurities.
10. To start the Grignard reaction, which one of the following steps should not be done
a) Add a tiny crystal of iodine
b) Cool the solution flask
c) Try to mash the metal with dry stirring rod.
d) Warm the flask in a water bath