Sublimation 2

Temperature:

Pressure:

Apparatus Setup:
Time:
Surface Cleanliness and Orientation:

Several variables influence the efficiency and success of the

sublimation process:

Temperature:

The heat applied must be enough to

induce sublimation but not so high as to cause

decomposition or melting.

decomposition or melting

Temperature: The heat applied must be enough to

induce sublimation but not so high as to cause

_ 2.

Temperature:

must be

gradually increased and carefully monitored.

increased and carefully monitored

Temperature must be

gradually _ 2.

Lowering

_ the pressure (as in vacuum

sublimation) reduces the sublimation point of many

solids, allowing sublimation to occur at lower and

safer temperatures.

vacuum

sublimation

Lowering the pressure (as in _) reduces the sublimation point of many

solids, allowing sublimation to occur at lower and

safer temperatures.

sublimation point

Lowering the pressure (as in vacuum

sublimation) reduces the _ of many

solids, allowing sublimation to occur at lower and

safer temperatures.

sublimation

Lowering the pressure (as in vacuum

sublimation) reduces the sublimation point of many

solids, allowing _ to occur at lower and

safer temperatures.

lower and

safer

Lowering the pressure (as in vacuum

sublimation) reduces the sublimation point of many

solids, allowing sublimation to occur at _ 2 temperatures.

pressure

Lowering the _ (as in vacuum

sublimation) reduces the sublimation point of many

solids, allowing sublimation to occur at lower and

safer temperatures.

Apparatus Setup:

The setup must include an

effective cold surface positioned directly above the

heated compound for the vapor to re-solidify. The

entire system must be sealed to prevent loss of

sublimated material.

effective cold surface

Apparatus Setup: The setup must include an

_ positioned directly above the

heated compound for the vapor to re-solidify. The

entire system must be sealed to prevent loss of

sublimated material.

heated compound

Apparatus Setup: The setup must include an

effective cold surface positioned directly above the

_ for the vapor to re-solidify. The

entire system must be sealed to prevent loss of

sublimated material.

sealed

Apparatus Setup: The setup must include an

effective cold surface positioned directly above the

heated compound for the vapor to re-solidify. The

entire system must be _ to prevent loss of

sublimated material.

sublimated material

Apparatus Setup: The setup must include an

effective cold surface positioned directly above the

heated compound for the vapor to re-solidify. The

entire system must be sealed to prevent loss of

_.

Rushing the process with excessive heat can

lead to melting or charring. Patience ensures higher

purity and better yield.

melting or charring

Time: Rushing the process with excessive heat can

lead to _ 2. Patience ensures higher

purity and better yield.

higher purity and better yield

Time: Rushing the process with excessive heat can

lead to melting or charring. Patience ensures_ 2

Surface Cleanliness and Orientation:

The cold

surface should be clean, properly angled, and

maintained at a lower temperature than the heat

source to promote condensation of the vapor.

cold

surface

Surface Cleanliness and Orientation: The _

should be clean, properly angled, and

maintained at a lower temperature than the heat

source to promote condensation of the vapor.

clean, properly angled, lower temperature

Surface Cleanliness and Orientation: The cold

surface should be _, ? and

maintained at a ? than the heat

source to promote condensation of the vapor.

condensation

Surface Cleanliness and Orientation: The cold

surface should be clean, properly angled, and

maintained at a lower temperature than the heat

source to promote _ of the vapor.

sublimation

After _, product purity can be evaluated visually and,

if available, analytically (e.g., melting point determination, thin-

layer chromatography).

product purity

After sublimation, _ can be evaluated visually and,

if available, analytically (e.g., melting point determination, thin-

layer chromatography).

visually

After sublimation, product purity can be evaluated _ and,

if available, analytically (e.g., melting point determination, thin-

layer chromatography).

analytically

After sublimation, product purity can be evaluated visually and,

if available, _ (e.g., melting point determination, thin-

layer chromatography).

melting point determination, thin-

layer chromatography

After sublimation, product purity can be evaluated visually and,

if available, analytically (e.g., _ 2).

sublimed

Visually, the _ product should

form sharp, uniform, colorless (or appropriately colored)

crystals.

sharp, uniform, colorless (or appropriately colored)

crystals

Visually, the sublimed product should

form _ 3.

final product

If the _ appears cloudy, contains multiple

colors, or includes specks or residue, it may still contain

impurities.

impurities

If the final product appears cloudy, contains multiple

colors, or includes specks or residue, it may still contain

_.

Melting point analysis

_ is particularly useful—pure

substances have sharp melting points, whereas impure

substances melt over a wider range.

pure

substances

Melting point analysis is particularly useful—____ have sharp melting points, whereas impure

substances melt over a wider range.

impure

substances

Melting point analysis is particularly useful—pure

substances have sharp melting points, whereas _ melt over a wider range.

separation,

overheating, or sublimation

Incomplete _ 3 of impurities can all affect the purity

of the final product.

purity

Incomplete separation,

overheating, or sublimation of impurities can all affect the _

of the final product.

Crude samples

_ often appear as heterogeneous mixtures with

uneven texture, discoloration, or mixed particles.

heterogeneous

Crude samples often appear as _ mixtures with

uneven texture, discoloration, or mixed particles.

Crude samples

They may be

sticky, oily, or clumped due to the presence of impurities or

residual solvents.

purified compound

After sublimation, the _

should be visibly improved—forming well-defined, crystalline

structures that are dry, brittle, and more homogenous in

appearance.

sublimation

After _, the purified compound

should be visibly improved—forming well-defined, crystalline

structures that are dry, brittle, and more homogenous in

appearance.

melts

If the compound _ instead of subliming, it typically

indicates a flaw in the experimental setup.

experimental

If the compound melts instead of subliming, it typically

indicates a flaw in the _ setup.

Excessive Heating:

Insufficient Cooling:

Poor Vacuum Conditions:

Incorrect Placement of Cold Surface:

Potential Setup Errors Leading to Melting 4

Excessive Heating:

Applying heat too rapidly or at

too high a temperature may exceed the melting point

rather than reaching the sublimation point.

melting

Excessive Heating: Applying heat too rapidly or at

too high a temperature may exceed the _ point

rather than reaching the sublimation point.

Insufficient Cooling:

If the cold surface is not cool

enough, the vapor may not condense efficiently,

which may cause pressure buildup or inefficient

deposition.

condense

Insufficient Cooling: If the cold surface is not cool

enough, the vapor may not _ efficiently,

which may cause pressure buildup or inefficient

deposition.

pressure buildup or inefficient

deposition

Insufficient Cooling: If the cold surface is not cool

enough, the vapor may not condense efficiently,

which may cause _ 2.

inadequate vacuum

Poor Vacuum Conditions: In vacuum sublimation,

_ reduces pressure control and can

shift the sublimation point unfavorably.

Poor Vacuum Conditions:

In vacuum sublimation,

inadequate vacuum reduces pressure control and can

shift the sublimation point unfavorably.

Incorrect Placement of Cold Surface:

If the condensation surface is too far or misaligned,

sublimated vapors may escape or fail to re-deposit.

sublimated vapors

Incorrect Placement of Cold Surface:

If the condensation surface is too far or misaligned,

_ may escape or fail to re-deposit.

Careful calibration and real-time observation

_ 2 can help prevent

these errors.

cold surface

The _ plays a central role in the sublimation process

by providing a site for the gaseous molecules to condense and

re-solidify as purified crystals.

chilled

watch glass or funnel

This surface, such as a _, must remain in position to ensure that

the vaporized compound does not escape the system.

product loss

If

removed or displaced too early, _will occur, and the

vapor may condense randomly or on unintended parts of the

apparatus.

deposition

The efficiency and completeness of _

directly depend on the temperature gradient between the

heated source and the cold surface.

cold

surface

A properly maintained _ enhances purity, yield, and crystal quality.

purity, yield, and crystal quality

A properly maintained cold

surface enhances _ 3.

heated source and the cold surface

The efficiency and completeness of deposition

directly depend on the temperature gradient between the

_ 2.

purified crystals

The cold surface plays a central role in the sublimation process

by providing a site for the gaseous molecules to condense and

re-solidify as _.