Question

distillation lab

1. On a given day in Denver, the typical barometric pressure is 630 mm Hg? How would that affect the observed boiling point of water?

2. How would an impurity affect the boiling point of a liquid?

a. What if the impurity was miscible?

b. What if the impurity was immiscible?

c. What if the impurity formed an azeotrope?

3. Why are there no units on the index of refraction?

4. Does the index of refraction uniquely identify a substance?

  

5. What errors in observed physical properties might lead to misidentification of a liquid?

a. boiling point errors

b. index of refraction errors

6. What observed FTIR resonances are most useful in distinguishing functional groups?

a. alcohols

b. ketones

7. What aspects of covalent bonds increases the vibrational energy?

a. atoms in the bonds

b. types of bonds (i.e. single, double, triple)

8. Why would a fractionating column be more efficient than a simple column at separating compounds that have boiling points that are less than 50 ^oC apart?

9. Compare and contrast these fractionating columns.

a. Unfilled condenser

b. Condenser filled with glass beads

c. Condenser filled with copper mesh

10. Why can't a two-component mixture that forms an azeotrope be purified by distillation?

Answer 1

Ans 1 : The boiling point will decrease.

The water attains its boiling point , when the internal pressure becomes equal to the external atmospheric pressure.

The boiling point of water is 100 degree Celcius at 1 atm or 760 mmHg , but in denver where the atmospheric pressure is low , i.e. 630 mmHg , less amount of heat energy would be required to push the vapour pressure of water beyond the atmospheric pressure which is already low.

So the water attains its boiling point , much faster at a lower temperature.