C5 Flashcards
What is a pure substance?
3
3
What is a mixture?
Substances that contain more than one element or compound.
4
4
What is a formulation?
Useful mixtures with a precise purpose that are made by following a recipe
-For example, paints are formulations.
4
5
In chromatography, what is the mobile phase?
Where the particles can move
-always a liquid or gas.
5
6
In chromatography, what is the stationary phase?
Where the particles can’t move.
5
7
Why is an equilibrium formed in chromatography?
Because substances in a sample constantly move between the mobile and stationary phase.
5
8
What is the relationship between distance travelled and time spent on mobile phase?
The longer the sample spends on the mobile phase, the further it will travel.
3
9
What is the Rf value?
Distance travelled by substance / distance by solvent front.
3
10
Why is filtration used?
To seperate insoluble salt from a liquid.
4
11
Why is crystallisation used?
To seperate a soluble solid from a solution.
3
12
Why is distillation used?
To separate out mixtures from liquids or solutions.
3
13
What do flame tests identify?
Metal ions.
4
14
What is flame emission spectroscopy used?
To analyse alloys.
3
15
What is the relative formula mass?
All the mass of a compound added together
3
16
What is the relative atomic mass?
The number of neutrons + protons in an element.
4
17
What is the explanation for if the mass increases in a reaction?
-Gas floating in the air may join the reaction.
3
18
What is thee explantaion for if the mass decreases in a reaction?
-Gases may escape from the reaction
3
19
What is a mole?
6 x 10*23 particles
5
20
How can you work out the number of moles?
Mass of element / Molar mass of element
5
21
What is the % yield?
mass of product made / theoretical mass of product made.
A substance that only contains 1 compound.
How does the melting point show how pure a substance is?
3
The closer your measured value is to the actual point, the purer the substance is.
What is a mixture?
4
Substances that contain more than one element or compound.
