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