OC-EXP 4 Sublimation

What is sublimation?

• The conversion of a substance from gas to liquid state

• The conversion of a substance from solid to gas state without passing through the liquid state

• The conversion of a substance from liquid to solid state

• The conversion of a substance from gas to solid state

When is sublimation applicable as a separation process?

• When the components have similar vapor pressures

• When the components have different melting points

• When the components have different boiling points

• When the components differ appreciably in their vapor pressures

How does sublimation separate components of a solid mixture?

• By melting the mixture and evaporating the liquid

• By converting one component directly into gas while leaving the other component behind

• By dissolving the mixture in a solvent and evaporating the solvent

• By filtering the mixture to separate the components

What is collected when the vapors from sublimation are condensed?

• Liquid component

• Solid component

• Gas component

• Crystalized component

Under what conditions is gentle heating applied in sublimation?

• Until the mixture boils vigorously

• Until all components evaporate

• Until the component with high vapor pressure changes into the vapor state

• Until the container reaches a high temperature

What is a limitation of sublimation as a separation process?

• It requires high pressure

• It cannot be applied to solid mixtures

• It is only applicable to organic compounds

• It can only be applied when components differ appreciably in their vapor pressures

When are sublimated crystals of the component with high vapor pressure collected?

• Before heating the solid mixture

• After the mixture has been heated to a high temperature

• After the vapors have condensed on a solid surface

• During the heating process

What is the primary purpose of sublimation in organic compound purification?

• To increase the melting point of the compound

• To decrease the boiling point of the compound

• To remove impurities and purify the compound

• To change the chemical composition of the compound

What is the purpose of boring a small hole in the filter paper covering the evaporating dish?

• To allow gases to escape during heating

• To prevent contamination from the surroundings

• To facilitate evaporation of the mixture

• To trap volatile components of the mixture

At what stage is the evaporating dish removed from the hotplate?

• When all the contents have evaporated

• When vapor is observed passing through the hole in the filter paper

• Immediately after heating begins

• After cooling the setup completely