ANALYTICAL AND LABORATORY
I:*:
.
TECHNIQUES:
Zainab Modan
, Separation vs Purification
In chemistry, a separation process is used to transform a mixture of substances into two or more distinct products.
• Separate methanol from ethanol
• Purification is the physical separation of a chemical substance of interest from contaminating substances.
• Purify ethanol (98%) to absolute ethanol (100%) by removing H2O impurity
Separation Techniques:
• Filtration
• Distillation
• Chromatography
• Crystallisation (Precipitation)
Filtration
• Filtration is a mechanical operation that separates the components of a
heterogeneous mixture on the basis of differences in particle size.
• It is used most often to separate a liquid from a solid.
• One component is in solution while the other is not—>The soluble component will
pass through the filter while the other component will be retained.
In the Lab:
• Fluids flow through the filter due to a difference in pressure – fluid flows from the high pressure side to
the low pressure side of the filter, leaving solid material behind.
• The simplest method to achieve this is by gravity e.g. the coffee filter to keep the coffee separate from
the grounds.
At Home:
• The solid remaining in the filter paper is called the residueand can be dried by spreading it out on
the filter paper and allowing the liquid to evaporate.
• The liquid which has passed through the filter paper is called the filtrate.
Vacuum Filtration:
• In the technique of vacuum filtration, the pressure of the flask is lowered to speed up the
process.
Some particles might block filter —> vacuum tube helps resolve this
Two main types of filter are employed in the chemical laboratory:
• A surface filter: a solid sieve which traps the solid particles, with or
without the aid of filter paper.
• A depth filter: a bed of granular materials which retains the solid
particles.
I:*:
.
TECHNIQUES:
Zainab Modan
, Separation vs Purification
In chemistry, a separation process is used to transform a mixture of substances into two or more distinct products.
• Separate methanol from ethanol
• Purification is the physical separation of a chemical substance of interest from contaminating substances.
• Purify ethanol (98%) to absolute ethanol (100%) by removing H2O impurity
Separation Techniques:
• Filtration
• Distillation
• Chromatography
• Crystallisation (Precipitation)
Filtration
• Filtration is a mechanical operation that separates the components of a
heterogeneous mixture on the basis of differences in particle size.
• It is used most often to separate a liquid from a solid.
• One component is in solution while the other is not—>The soluble component will
pass through the filter while the other component will be retained.
In the Lab:
• Fluids flow through the filter due to a difference in pressure – fluid flows from the high pressure side to
the low pressure side of the filter, leaving solid material behind.
• The simplest method to achieve this is by gravity e.g. the coffee filter to keep the coffee separate from
the grounds.
At Home:
• The solid remaining in the filter paper is called the residueand can be dried by spreading it out on
the filter paper and allowing the liquid to evaporate.
• The liquid which has passed through the filter paper is called the filtrate.
Vacuum Filtration:
• In the technique of vacuum filtration, the pressure of the flask is lowered to speed up the
process.
Some particles might block filter —> vacuum tube helps resolve this
Two main types of filter are employed in the chemical laboratory:
• A surface filter: a solid sieve which traps the solid particles, with or
without the aid of filter paper.
• A depth filter: a bed of granular materials which retains the solid
particles.
