Chemical Analysis Flashcards
What is a pure substance?
Made up of single element or compound.
Not mixed with any other substance.
Has definite melting and boiling points.
What is a formulation?
Mixture that been designed as useful product.
Made by mixing several different substances I carefully measured quantities.
Ensure products has required properties.
What is filtration?
Separates insoluble solid from solution.
Residue is caught in filter paper.
Filtrate passes through and collected as drips out spout of funnel.
What does simple distillation collect?
Solvent (liquid) from solution.
How does simple distillation work?
Separating solution which contains mixture of solid (solute) and liquid (solvent).
Liquid boiled off in flask the vapour cooled (Liebig condenser), so it condenses back to liquid.
Collected liquid called distillate.
Two processes used - evaporation and condensation.
Examples for simple distillation.
Salt and water.
Ink and water.
What are important things to know about simple distillation?
Thermometer adjacent to condenser outlet.
Condenser at slant.
Cold water in at bottom of condenser and hot water out at top.
Anti-bumping granules priced large surface area for bubbles to form on and ensure smooth boiling.
When is fractional distillation used?
Boiling points of miscible liquids in mixture very close together.
Examples for fractional distillation.
Ethanol and water.
How does simple distillation work?
Each liquid evaporate at different boiling point and can be collected separately.
How does separating funnel work?
Separating mixture of immiscible liquids (do not mix together).
Lower liquid layer drained off carefully using tap.
Examples of separating funnel.
Oil (upper layer) and water.
What is potable water?
Water safe to drink.
How is potable water obtained?
From fresh water or seawater but source needs to be treated before fit to drink.
What is the method for chromatography?
- Using pencil, draw base line on chromatography paper around 1-2cm from bottom. Pencil as will not dissolve in solvent.
- Using capillary tube, place spot of substance to be analysed on base line. When dry add another spot on top to make concentrated.
- Place paper in beaker with solvent at bottom. Pencil line and spots must be above level of solvent so spots do not dissolve into solvent in beaker.
- Solvent travels up paper.
- When solvent near top, take paper out of solvent and mark level that solvent reached. This is solvent front.
- Leave paper to dry. Mixture should have separated into different components, seen as spots on paper.
What is the equation for the retardation factor of chromatography?
Distance moved by spot divided by distance moved by solvent.
How is potable water obtained from freshwater?
Filtration - removed insoluble solids.
Sedimentation - aluminium sulfate clumps tiny particles together, settle at bottom and filtered off.
Chlorination - bubbled in to kill miscounted and bacteria, sterilise water.
How is potable water obtained from seawater?
Desalination - removed dissolved substances from sea water and carried it by distillation.
What is the test for water?
Water added to anhydrous copper(II) sulfate, colour change from white to blue and hydrated copper (II) sulfate formed.
Test for cations for Cu2+.
Addition of NaOH - blue precipitate
Excess NaOH - solid remains
Addition of NH3 - dark blue precipitate
Excess NH3 - dark blue solution
Test for cations of Fe2+.
Addition of NaOH - green precipitate
Excess NaOH - solid remains
Addition of NH3 - green precipitate
Excess NH3 - solid remains
Test for cations of Zn2+.
Addition of NaOH - white precipitate
Excess NaOH - colourless solution produced
Addition of NH3 - white precipitate
Excess NH3 - colourless solution produced
Test for cations of Fe3+.
Addition of NaOH - brown precipitate
Excess NaOH - solid remains
Addition of NH3 - brown precipitate
Excess NH3 - solid remains
Test for cations of Al3+.
Addition of NaOH - white precipitate
Excess of NaOH - colourless solution produced
Addition of NH3 - white precipitate
Excess NH3 - solid remains
Test for cations of Mg2+.
Addition of NaOH - white precipitate
Excess NaOH - solid remains
Addition of NH3 - white precipitate
Excess NH3 - solid remains
Test for halides of chlorine.
Addition of silver nitrate - white
Addition of few drops NH3 - solid redissolves
Addition of concentrated NH3 - colourless
Relations on adding silver nitrate - white pot of silver chloride
Word equation - silver nitrate + sodium chloride > silver chloride + sodium nitrate
Test for halides of bromine.
Addition of silver nitrate - cream
Addition of few drops NH3 - doesn’t change
Addition of concentrated NH3 - solid redissolved
Result on adding silver nitrate - cream ppt sliver bromide
Word equation - silver nitrate + sodium bromide > silver bromide + sodium nitrate
Test for halides of iodide.
Addition of silver nitrate - yellow
Addition of few drops NH3 - doesn’t change
Addition of concentrated NH3 - doesn’t change
Result on adding silver nitrate - yellow ppt silver iodide
Word equation - silver nitrate + sodium iodide > silver iodide + sodium nitrate
What is the test for sulfate ions?
Sodium sulfate + barium chloride > turns to white precipitate
Ionic equation - Ba+(aq) + SO42- (aq) > BaSO4(s)
Method for test for carbonate ions.
- Add dilute hydrochloric acid to solid
- Test gas produced with limewater.
