Topic 8-C12

Question 1

What does it mean for a substance to be pure

Answer 1

A pure substance is when there is only one thing in the substance, for example pure water is just H2O molecules

Question 2

How can you tell how pure a substance is

Answer 2

The more pure a substance is, the closer the boiling or melting point will be to its real value.
If a substance is not pure it will melt or boil over a range

Question 3

What is a formulation

Answer 3

A forumulation is a mixture with an exact ratio of components

Question 4

What is chromatography and what are the two phases in it

Answer 4

Chromatography is when you separate the substances in a mixture,
the two phases are the mobile phase and the stationary phase

Question 5

After a chromatograph is made what is done with the Rf value

Answer 5

It is compared with the reference to see if Rf values are the same

Question 6

What is the formula for the Rf value

Answer 6

Rf=distance travelled by substance/distance travelled by solvent

Question 7

What is flame emission spectroscopy

Answer 7

Flame emission spectroscopy is when metals are heated and then cooled and they give off energy as light as their energy levels fall back to their original.
The light then passes through a spectroscope where it can detect different wavelengths of the light and display them as coloured lines called a line spectrum

Question 8

How can they tell what is in a substance from FES

Answer 8

They compare the line spectrum of the substance to rederence line spectrums of ions found in metals