3.Leaching

DAY 2: CHEMICAL ENGINEERING –Leaching

LEACHING Review Questions 1.

Which of the following operations does not involve leaching? a. dissolving gold from ores b. dissolving pharmaceutical products from bark or roots c. dissolving sugar from the cells of the best d. removing nicotine from its water solution by kerosene

2.

Tea percolation employs a. liquid-liquid extraction b. leaching

c. absorption d. adsorption

Rate of leaching increases with increasing a. temperature b. viscosity of solvent

c. pressure d. size of the solid

3.

4.

Stage efficiency in a leaching process depends on the a. time of contact between the solid and the solution b. rate of diffusion of the solute through the solid and into the liquid c. both a and b d. vapor pressure of the solution

5.

Extraction of coffee from its seed is done by a. liquid-liquid extraction b. leaching

c. extractive distillation d. steam distillation

Leaching of sugar from sugar beets is done by a. hot water b. hexane

c. dilute H2SO4 d. lime water

6.

7.

With increase in temperature, the leaching rate increases due to a. decreased liquid viscosity c. both a and b b. increased diffusivity d. neither a nor b

8.

Leaching rate is independent of the a. agitation b. particle size

c. temperature d. none of these