Chemistry - CH2 - States of matter and mixtures

What are the properties of solid state?

Strong forces of attraction, fixed position

What are the properties of liquid state?

Weak forces of attraction, free to move, definite volume

What are the properties of gaseous state?

Very weak forces of attraction, constantly moving

What is the definition of a pure substance?

Contains only one type of compound or element

What is the definition of mixture?

Two different compounds

What is a physical test?

Testing the physical properties

What is a chemical test?

Reacting the substance with another chemical

How does impure substances affect the melting and boiling point?

It ranges its temperature

In samples, how do impure substances change the melting and boiling points?

They lower the melting point and increase the boiling point

What is the definition of formulations?

Mixtures that have been prepared using a specific formula

What is the purpose of simple distillation?

Used to separate a liquid from a mixture, but we still want to keep the liquid

Describe the process of simple distillation

The solution is placed in a flask and heated so that the liquid evaporates into vapour. The vapour passes through a condenser and condenses back into liquid which is collected

Why can you not use simple distillation for mixtures that contain multiple different liquids?

The liquids may have the same boiling points so would evaporate together

When would fractional distillation be used rather than simple distillation?

When the mixture contains multiple liquids with similar boiling points

How does fractional distillation work?

A solution is gently heated, the liquid with the lowest boiling point evaporates and passes through the fractioning column. It goes through the condenser and condenses back into liquid. This process then repeats

What is the fractioning column filled with and why is it used?

Glass rods - provide a large surface area which cause gases to condense back to liquids

What are the 6 methods through which mixtures can be separated?

Filtration, chromatography, crystallisation, evaporation, simple distillation and fractional distillation

What is filtration used for?

To separate insoluble solids from liquids

What is the filtrate in filtration?

Any liquid or dissolved substance that passes through the filter paper

What is the residue in filtration?

Any insoluble solids caught by the filter paper

What is evaporation used for?

Separate a dissolved solid from a liquid

What is chromatography used for?

To separate mixtures and give information to help identify substances

What is the mobile phase in chromatography?

The solvent

What is the stationary phase in chromatography?

The paper

How many spots do pure substances produce in paper chromatography?

One spot

How many spots do impure substances produce in paper chromatography?

More than one

What is an Rf value?

The ratio between the distance travelled by the dissolved substance and the distance travelled by the solvent

How to calculate Rf value?

Distance travelled by substance / distance travelled by solvent

What does potable mean?

Safe to drink