Chemical Analysis Flashcards
How do you know if a substance is pure?
It has a specific melting and boiling point
How can you measure if something is pure?
By measuring its boiling and melting points and comparing it to a pure substances boiling and melting point
The closer to the specific melting and boiling point the purer the substance
What will impurities have?
Lower melting point- increase the melting range
Higher boiling point
What are formulations?
Useful mixtures with exact amount of components for a precise purpose
Why are formulations important in the pharmaceutical industry?
Altering the formulation of a pill can deliver the drug to the correct part of the body at the right concentration
What is the test for chlorine?
Bleaches damp litmus paper white
If you use blue litmus paper it will go red (acidic)
What is the test for oxygen?
Glowing splint in a test tube, splint will relight
What is the test for hydrogen?
Burning splint at the open end of a test tube, a squeaky pop noise will be made
What is the test for carbon dioxide?
Bubble CO2 through limewater (calcium hydroxide), turns cloudy
How do you work out the Rf value?
Distance of spot / distance of solvent
What is a mobile phase?
When the molecules can move (liquid or gas)
What is a stationary phase?
When the molecules can’t move (solid or thick liquid)
What effects the amount of time the molecules spend in each phase?
How soluble they are in the solvent
How attracted they are to the paper
What will molecules with a higher solubility do?
Spend more time in the mobile phase as they are less attracted to the paper
What is the Rf value dependant on?
The solvent you use if you change the solvent the Rf value will change
How do you test for carbonates?
Dropping pipette to add dilute acid
Connect the test tube to a test tube containing limewater
Limewater will go cloudy
How do you test for sulphates wit barium chloride?
Dropping pipette to add dilute hydrochloric acid and barium chloride
White precipitate will form
How do you test for halides with nitric acid and silver nitrate?
Add nitric acid to remover carbonate ions
The add silver nitrate
What colour precipitate will chloride form?
White
What colour precipitate will bromide form?
Cream
What colour precipitate will iodide form?
Yellow
What colour flame does lithium produce?
Crimson
What colour flame does sodium produce?
Yellow
What colour flame does potassium produce?
Lilac
What colour flame does calcium produce?
Orange
What colour flame does copper produce?
Green
How do you test for metal ions?
Dip a nichrome loop in hydrochloric acid to clean
Put the nichrome loop in a roaring flame to clean
Put the nichrome loop in metal ion
Put nichrome loop with metal ion into flame
Record colour and repeat cleaning process and repeat
Dip back into acid
How do you test for insoluble metal hydroxides?
Add sodium hydroxide solution to a mystery solution
What will be the precipitate colour of calcium insoluble hydroxide?
White
What will be the precipitate colour of copper insoluble hydroxide?
Blue
What will be the precipitate colour of iron II insoluble hydroxide?
Green
What will be the precipitate colour of iron III insoluble hydroxide?
Brown
What will be the precipitate colour of aluminium insoluble hydroxide?
White at first the goes colourless
What will be the precipitate colour of magnesium insoluble hydroxide?
White
What happens in flame emission spectroscopy as the ions heat up?
Electrons get excited and move up higher energy levels
When the electrons drop back to their original energy levels they release energy
What does the intensity of the spectrum indicate and what does this mean?
The concentration of the ion in the solution
So the line spectra can be used to identify ions and calculate their concentrations
Why does ions produce different line spectrums?
Different ions have different wavelengths so they produce different pattern of wavelengths
What are the advantages of flame emission spectroscopy?
Very sensitive- can detect tiniest amount of substance
Very fast
Very accurate
