Question

Cooling an acetanilide mixture with an ice bath has resulted in a heavier amount of acetanilide crystals than cooling the container slowly. Some say increasing the cooling rate can include impurities, while others argue that decreasing the cooling rate allows the crystal to grow. What is the primary reason for the difference in acetanilide crystal mass between rapid and slow cooling?

a) Increased impurities
b) Crystal growth
c) Temperature fluctuations
d) Chemical reactions

Answer 1

The primary reason for the difference in acetanilide crystal mass between rapid and slow cooling is b. crystal growth. Increasing the cooling rate may trap impurities, while decreasing the cooling rate allows crystals to grow. Rapid cooling doesn't provide sufficient time for proper crystal formation.

Step-by-step explanation:

The primary reason for the difference in acetanilide crystal mass between rapid and slow cooling is b. crystal growth. When a solution is cooled slowly, the molecules have time to arrange themselves in an ordered lattice structure, resulting in larger and more well-formed crystals.

On the other hand, rapid cooling leads to a faster decrease in temperature, which doesn't allow sufficient time for the molecules to arrange themselves properly, resulting in smaller and less well-formed crystals.

Additionally, increasing the cooling rate doesn't necessarily include impurities, but it may increase the chance of trapping impurities within the crystals if they form too quickly. Decreasing the cooling rate allows the crystals to grow to a larger size and gives impurities a better chance of being excluded.