lectures for Gcse students paper chromatography purity of substances method of purification

1. CHEMISTRY
IGCSE/GCSE

2. 1.PARTICLES AND
PURIFICATION
PART 1
1.1 SOLIDS, LIQUID, GASES
1.2 DIFFUSION
1.3 APPARATUS FOR MEASURING
PART 2
1.4 PAPER CHROMATOGRAPHY
1.5 PURITY OF SUBSTANCE
1.6 METHOD OF PURIFICATION

3. Paper chromatography
the method of separating
pigments(coloured
substances) using filter paper

4. FACTORS DETERMINING HOW FAST THE
PIGMENTS MOVE ACROSS THE FILTER PAPER
The pigment have
different
solubilities in the
solvent
The pigment have
different degrees
of attraction for the
the filter paprer
The type of solvent
also effect how far
the pigment will
travel across the
paper
USES OF CHROMATOGRAPHY:
1.identifing the substances in
the mixture
2.Seperation and purification of
the substance in the mixture

5. CHROMATOGRAPHY

6. MORE ABOUT CHROMATOGRAPHY

7. PURE SUBSTANCES
• A PURE SUBSTANCE CONSISTS ONLY
OF ONE ELEMENT OR ONE COMPOUND
• A MIXTURE CONSISTS OF TWO OR
MORE DIFFERENT SUBSTANCES, NOT
CHEMICALLY JOINED TOGETHER
• DIFFERENT TYPES OF CHEMICAL
SUBSTANCE
• AN ELEMENT CONTAINS JUST ONE
TYPE OF ATOM
• A COMPOUND CONTAINS TWO OR
MORE TYPES OF ATOM JOINED
TOGETHER
• A MIXTURE CONTAINS TWO OR
MORE DIFFERENT SUBSTANCES THAT
ARE NOT JOINED TOGETHER
• THE DIFFERENT SUBSTANCES IN A
MIXTURE CAN BE ELEMENTS OR
COMPOUNDS

8. THE DIFFERENCE BETWEEN COMPOUND AND
MIXTURE
COMPOUND
• COMPOUND HAVE A FIXED COMPOSITION(THE
RATIO OF ELEMENTS PRESENT IS ALWAYS THE SAME
IN ANY PARTICULAR COMPOUND).
• CHEMICAL REACTION MUST BE USED TO SEPARATE
THE ELEMENTS IN A COMPOUND.
• THERE ARE CHEMICAL BOUNDS BETWEEN ATOMS OF
THE DIFFERENT ELEMENTS IN THE COMPOUND.
MIXTURE
• MIXTURES HAVE NO FIXED COMPOSITION(THE
PROPORTIONS VARY DEPENDING ON THE AMOUNT
OF EACH SUBSTANCE MIXED TOGETHER)
• THE DIFFERENT ELEMENT OR COMPOUNDS IN A
MIXTURE CAN BE SEPARATED AGAIN MORE EASILY (
BY PHYSICAL MEANS USING THE DIFFERENCES IN
PROPERTIES OF EACH SUBSTANCE IN A MIXTURE)
• THERE ARE NO CHEMICAL BONDS BETWEEN ATOMS
OF DIFFERENT SUBSTANCES IN A MIXTURE.

9. PURITY OF SUBSTANCE
• WHY PURITY IS IMPORTANT
• PURE ORANGE JUICE
• DISTILLED WATER
• MEDICINAL DRUGS
• PURE SILICON
• HOW DO WE KNOW IF THE
SUBSTANCE IS PURE
• CHROMATOGRAPHY
• MELTING AND BOILING POINT
• EFFECT OF IMPURITIES ON MELTING
AND BOILING POINT
• THE MP AND BP ARE NOT SHARP IN
IMPURE SUBSTANCE
• THE BP INCREASED BY IMPURITIES
• THE MP DECREASES BY IMPURITIES

10. Distinguishing between pure substances and mixtures
Pure substances have a sharp melting point but mixtures
melt over a range of temperatures. This difference is most
easily seen when the temperature of a hot liquid is
measured as it cools and freezes. The graph shows the
cooling curve for a sample of a compound called salol.
A cooling curve for salol
The temperature stays the same while a pure substance
changes state
The horizontal part of the graph shows that the salol has a
sharp melting point, so it is pure. Impure salol (a mixture
of salol and other substances) would produce a gradual
decrease over a range of temperatures as it freezes.
Graph of the freezing and melting range of a sunstance,
between 40 c and 50 c.
The temperature changes slightly as an impure substance
changes state

11. HOW DO WE PURIFY MIXTURES
• SOLIDS FROM LIQUIDS
• FILTRATION
• DECANTING
• CENTRIFUGATION
• WASHED AND REMOVED
• DISSOLVED SOLIDS FROM
LIQUIDS
• EVAPORATION
• LIQUIDS FROM LIQUIDS
• FRACTIONAL DISTILLATION

12. SEPARATING A SOLID FROM A SOLUTION
FILTRATION DECANTING CENTRIFUGE CRYSTALLIZATION

13. SOLVENT EXTRACTION

14. PURIFICATION
SIMPLE DISTILLATION AND FRACTIONAL
DISTILLATION

15. PURIFICATION
PURIFY THE MIXTURE OF SALT AND SAND
• ADD WATER TO DISSOLVE THE SALT
• SEPARATE SANT AND SALT BY FILLTRATION
• USE THE PROCESS OF CRYSTALLIZATION TO FORM SALT
CRYSTALS
• RISN THE SAND WITH DISTILLED WATER
• DRY THE SAND AND SALT CRYSTALS SEPERATELY ON FILTER

16. THANK
YOU
CHEMISTRY WITH ANUM