Mixtures and their Separation

Question 1

What is a mixture?

Answer 1

A mixture is a material made up of two or more different chemical substance/substances which are not chemically combined

Question 2

What is a Homogeneous mixture?

Answer 2

A mixture that is uniformed throughout. No difference in colour or particle concentration can be discerned in this type of mixture. Eg. seawater, alloys, alcohol and water.

Question 3

What is a Heterogeneous mixture?

Answer 3

A mixture that is not uniformed throughout. Different layers or different types of particles can be seen. Eg. sand and water, oil and water, sand and salt.

Question 4

What is a Solution?

Answer 4

A solution is formed when one substance called a solute dissolves in another is called a solvent. Solutions are homogeneous mixtures.

Question 5

What is a Suspension?

Answer 5

Suspension is a type of mixture formed when a solute doesn’t dissolve in a solvent. Eg. sand and water, chak and water

Question 5

What is a Colloid?

Answer 5

A colloid is a mixture where the solute particles are bigger than those in a solution but smaller than those in a solution. Eg. glue, gelatin, starch and water, toothpaste, fog, aerosol, gel, jelly.

Question 6

What is an Emulsion?

Answer 6

Emulsion are types of colloids where one liquid is finely dispersed in another liquid. Eg. mayonnaise, milk, foam

Question 7

List four ways to separate mixtures.

Answer 7

Sublimation, Centrifugation and Decantation, Filtration, Evaporation and Crystallisation, Simple Distillation, Separating Funnel, Solvent Extraction, Fractional Distillation, Paper Chromatography.

Question 8

What is Sublimation?

Answer 8

Sublimation is the method used to separate a substance which sublimes from a mixture.

Question 9

Describe the process of Sublimation.

Answer 9

The mixture is heated in an evaporating dish covered with a filter funnel. The substance which sublimes will be changed into a vapour and then formed back on the inside of the funnel.

Question 10

State 2 examples of mixtures that use Sublimation as the separation method.

Answer 10

Iodine, Ammonium salts, Naphthalene and dry ice.

Question 11

What is Decantation?

Answer 11

Decantation is a process for the separation of mixtures of immiscible liquids or of a liquid and a solid mixture such as a suspension.

Question 12

Describe the process of Decantation.

Answer 12

The mixture is left undisturbed until all the solid particles settle out. The liquid layer is then is carefully poured or decanted off, leaving the solid residue behind.

Question 13

State an example of mixtures that use Decantation as the separation method.

Answer 13

sand and water.

Question 14

What is Filtration?

Answer 14

Filtration is the process in which solid particles in a liquid are removed by the use of a filter

Question 15

Describe the process of Filtration.

Answer 15

Pour the mixture into the filter. The solid left on the filter paper is called residue. The liquid that has passed through the filter paper is called filtrate.

Question 16

State 2 examples of mixtures that use Filtration as the separation method.

Answer 16

sand and water, dirt and water.

Question 17

Describe the process of Evaporation and Crystallisation?

Answer 17

This method can be used to separate a solid/liquid solution. The mixture is heated in the evaporating dish. The liquid solvent boils off so that the solution becomes increasingly concentrated. When the solution is supersaturated, crystals begin forming. If the solution cools crystallisation occurs. The crystals are then washed and dried.