Separating Mixtures

Question 1

What is filtration and what does it seperate?

Answer 1

• separates an insoluble solid from a liquid
• mixture passes through filter paper to leave filtrate and residue

Question 2

What is evaporation and what does it separate?

Answer 2

• separates soluble solid from a solution
• heat solution until solvent evaporates away

Question 3

What is distillation and what does it separate?

Answer 3

• separates solvent from solution
• heat solution until solvent evaporates, then it goes through a condenser until it condenses into liquid

Question 4

What is fractional distillation and what does it separate?

Answer 4

• separates two miscible liquids with different boiling points
• heat until liquid a reaches boiling point, it evaporates and rises, goes through a condenser and turns back into liquid form

Question 5

Define miscible

Answer 5

Liquids that mix

Question 6

Define immiscible

Answer 6

Liquids that don’t mix

Question 7

What does a separating funnel separate and how does it work?

Answer 7

• separates immiscible liquids
• higher density liquid sinks, funnel can be opened to let it run out

Question 8

What is chromatography and what does it separate?

Answer 8

• separates several solids all soluble in same solvent, e.g dyes
• dyes placed at base of paper, and placed in solvent
• as solvent moves up paper, it moves dyes at different rates depending on their speed in the solvent
• more soluble dyes move faster up paper
• less soluble dyes move slower up paper

Question 9

What is the mobile phase in chromatography?

Answer 9

The solvent

Question 10

What is the stationary phase in chromatography?

Answer 10

The paper

Question 11

How to calculate Rf value?

Answer 11

Distance moved by pigment
——‐-‐————————————————
Distance from pigment origin to solvent front

Question 12

What is recrystallisation?

Answer 12

A method of purifying a solid and removing both insoluble and soluble impurities