Tag: separation methods

Questions Related to separation methods

Sublimation is used to purify:

chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

  1. plasma

  2. gases

  3. solids

  4. liquids

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Correct Option: C
Explanation:

Sublimation is a technique that helps chemists to purify. During sublimation,upon heating, a solid substance is converted to the gas phase without passing through the liquid phase.  A solid is heated under vacuum. The solid volatilizes and condenses as a purified compound on a cooled surface, a non-volatile residue of impurities is left behind.

Which one of the following substances is a mixture?

chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

  1. Water

  2. Copper

  3. Seawater

  4. Salt

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Correct Option: C
Explanation:

Sea water is a mixture. It contains water and dissolved minerals. Water and salt are compounds. Copper is element.

Process in which solid is directly converted to vapors state is called:

chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

  1. sublimation

  2. filtration

  3. drying

  4. cooling

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Correct Option: A
Explanation:

Sublimation is a technique that helps chemists to purify. During sublimation,upon heating, a solid substance is converted to the gas phase without passing through the liquid phase.  A solid is heated under vacuum. The solid volatilizes and condenses as a purified compound on a cooled surface,  a non-volatile residue of impurities is left behind.

Condensed solid produced during sublimation is:

chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

  1. crystals

  2. sublimate

  3. residue

  4. insoluble

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Correct Option: B
Explanation:

Condensed solid produced during sublimation is sublimate. Thus, sublimate is a solid deposit of a substance which has sublimed.

Sublimation can be used to separate a mixture of solids in which:

chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

  1. one sublimes other does not

  2. both sublimes

  3. both does not sublime

  4. sublimation cannot be used for separation

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Correct Option: A
Explanation:

Sublimation can be used to separate a mixture of solids in which one sublimes other does not. Thus, ammonium chloride can be separated from sodium chloride by sublimation. Ammonium chloride sublimes whereas sodium chloride does not.

The combustion of candles, containing paraffin wax, to carbon dioxide and water vapour is sublimation.
chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

  1. True

  2. False

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Correct Option: B
Explanation:

The term sublimation refers to a physical change of state and is not used to describe transformation of a solid to a gas in a chemical reaction. The combustion of candles, containing paraffin wax, to carbon dioxide and water vapor is not sublimation but a chemical reaction with oxygen.

On heating iodine and sand which will sublime?

chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

  1. Sand

  2. Iodine

  3. Both a and b

  4. None of them

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Correct Option: B
Explanation:

Iodine is a chemical element with atomic number 53. The heaviest of the stable halogens, it exists as a lustrous, purple-black metallic solid at a standard conditions that sublimes readily to form a violet gas.

Sublimation process is used:

chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

  1. to separate mixtures that contain a sublimate with a non-volatile component from a non-sublimate impurity

  2. to separate mixtures that contain a sublimate with a volatile component from a non-sublimate volatile impurity

  3. to separate mixtures that contain a sublimate with a volatile component from a non-sublimate impurity

  4. none of above

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Correct Option: C
Explanation:

Sublimation process is used to separate mixtures that contain a sublimate with a volatile component from a non-sublimate impurity. Thus, ammonium chloride can be separated from sodium chloride by sublimation. Ammonium chloride sublimes whereas sodium chloride does not.

Method of separation by sublimation is limited. 
chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

  1. True

  2. False

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Correct Option: A
Explanation:

The given statement is True.
 Method of separation by sublimation is limited. This method can be used for separation of only those compounds that sublime (i.e, change their state on heating from solid to vapour without passing through liquid state). Examples of sublimable compounds include iodine, ammonium chloride, camphor and naphthalene.

Note: If in the given mixture, none of the compounds is sublimable, then method of separation by sublimation cannot be used.

Ammonium chloride is separated from a mixture of sodium chloride and ammonium chloride by the process of:

chemistry separation of matter sedimentation, decantation and filtration other methods of separation separation methods

  1. evaporation

  2. sublimation

  3. fractional distillation

  4. filtration

Show answer
Correct Option: B
Explanation:

Ammonium chloride is separated from a mixture of sodium chloride and ammonium chloride by the process of sublimation. Ammonium chloride can be sublimed whereas sodium chloride cannot be sublimed. When a mixture of sodium chloride and ammonium chloride is heated, ammonium chloride changes its state from solid to vapour. The vapours of ammonium chloride are then condensed on cold surface. Sodium chloride is left behind.