1.11: Understand How a Chromatogram Provides Information about the Composition of a Mixture

PAPER CHROMATOGRAPHY - COMPOSITION OF A MIXTURE

Diagram showing the Composition of an Ink using Paper Chromatography

COMPOSITION OF A MIXTURE: Chromatogram shows the composition of mixture as different coloured substances (components) and will spread apart as they have different solubilities so will travel at different rates Pure susbtance will only produce one spot on chromatogram during paper chromatography In the diagram above, Red, Blue, and Yellow are three pure substances, whilst sample on left is a mixture of all three

1.12: Understand How to Use the Calculation of Rf Values to Identify the Components of a Mixture

Rf VALUES: Used to identify the components of mixtures

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• Rf value of a particular compound is always the same
• This allows industries to use chromatography to identify compounds in mixtures

EQUATION:

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Rf Value =     Distance Moved by Compound    ÷     Distance Moved by Solvent

1.13: Practical: Investigate Paper Chromatography using Inks / Food Colourings

PAPER CHROMATOGRAPHY

Diagram showing the Paper Chromatography of Ink and Plant Dye

USE: To separate substances that have different solubilities in a given solvent (E.g Different coloured Inks mixed to form black ink)

METHOD: Pencil line is drawn on chromatography paper and a concentrated spot of ink/dye is placed on it PPaper is lowered into bucket of solvent, allowing solvent to travel up the paper taking particles of coloured substance with it Allow chromatography to occur until solvent reaches top of paper

RESULTS: As solvent travels up the paper, different substances have different solubilities so will travel at different rates, causing substances to spread apart This will show the different components of the ink/dye

1.15: Know the Structure of an Atom in Terms of the Positions, Relative Masses and Relative Charges of Sub-Atomic Particles

Atoms are made up of sub-atomic particles called Protons, Neutrons and Electrons

PARTICLE	RELATIVE CHARGE	RELATIVE MASS
PROTON	+1	1
NEUTRON	0	1
ELECTRON	-1	1/1836

1.14: Know What is Meant by the Terms Atom and Molecule

DEFINITIONS:

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TERM	DEFINITION
ATOM	Smallest particle of an Element that consists of Electrons surrounding a Nucleus that contains Protons and Neutrons
MOLECULE	Smallest particle of a substance that is formed when Atoms join together by chemical bonds

1.17: Be Able to Calculate the Relative Atomic Mass of an Element (Ar) from Isotopic Abundances

ISOTOPES: Atoms of the same Element that contains the same Atomic Number but different Mass Number

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EQUATION:

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(% of Isotope 1 x Mass of Isotope 1 ) + ( % of Isotope 2 x Mass of Isotope 2) Ar =   _______________________________________________________________                                                                      100

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Example:

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The Table Shows Information about the Isotopes in a sample of Rubidium ISOTOPE NUMBER OF PROTONS NUMBER OF NEUTRONS PERCENTAGE OF ISOTOPE IN SAMPLE 1 37 48 72 2 37 50 28       Use information from the table to calculate the Relative Atomic Mass of        this Sample of Rubidium. Give your answer to one decimal place     (   72   x   85   )   +   (   28   x   87   )     ____________________________     =   85.6                              100     Relative Atomic Mass = 85.6

1.16: Know What is Meant by the Terms Atomic Number, Mass Number, Isotopes and Relative Atomic Mass (Ar)

DEFINITIONS:

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TERM	DEFINITION
ATOMIC NUMBER	Number of Protons in the Nucleus of an Atom
MASS NUMBER	Sum of number of Protons and Neutrons in the Nucleus of an Atom
ISOTOPES	Atoms of the same Element that contains the same Atomic Number but different Mass Number
RELATIVE ATOMIC MASS (Ar)	Measure of the mass of one Atom of the Element