Purity, formulations and chromatography Flashcards

1
Q

What is a pure substance?

A

A single element or compound not mixed with any other substance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How can you tell the difference between a pure substance and a mixture?

A

Pure substances have fixed melting & boiling points. Mixtures melt and boil within a range of melting and boiling points.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What can a “pure substance” mean in everyday language?

A

A substance that has had nothing added to it, so it is unadulterated and in its natural state, e.g. pure milk or pure orange juice.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is formulation?

A

A mixture that has been designed as a useful product

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How is formulation made?

A

A formulation is made by mixing specific quantities of different substances to make something useful.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Give 7 examples of a formulation.

A

Fuels, cleaning products, paints, medicines, alloys, fertilisers and foods.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is chromatography useful?

A

It can be used to separate mixtures and can give information to help identify substances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How are mixtures separated by chromatography?

A

Chromatography involves a stationary phase (e.g. paper) and a mobile phase (e.g. solvent). Separation depends on the relative attraction between the stationary phase and the mobile phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the Rf value of a compound?

A

The ratio of the distance moved by the substance to the distance moved by the solvent.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the equation for calculating the Rf value of a compound?

A

Rf = distance moved by the substance ÷ distance moved by the solvent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How can Rf values be used to identify different compounds?

A

Different compounds have different Rf values in different solvents.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How can chromatography be used to distinguish pure substances from impure substances or mixtures?

A

The substances in a mixture may separate into different spots depending on the solvent but a pure substance will produce a single spot in all solvents.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly