Chemical Analysis Flashcards
(24 cards)
What does it mean if a substance is pure?
Nothing has been added to it and it is in its natural state eg (pure milk)
What is a formulation?
Useful mixtures with a precise purpose that are made by following a ‘formula’
Why are formulations important in the pharmaceutical industry?
- Found in cleaning products, fuels, cosmetics etc
- by altering formulation of a pill, chemists can make sure it delivers drug to correct part of body at right concentration
How do you test for chlorine gas?
Chlorine bleaches damp litmus paper, turning it white. (With blue paper it May turn red for a moment because chlorine is acidic)
How do you test for oxygen?
Put a glowing splint inside a test tube containing oxygen, the oxygen will relight the glowing splint
How do you test for carbon dioxide?
Bubbling carbon dioxide through an aqueous solution of limewater, carbon dioxide causes solution to turn cloudy
How do you test for hydrogen?
If you hold a burning splint at the open end of a test tube containing hydrogen, you’ll get a squeaky pop.
What is the purpose of chromatography?
Used to separate the substances in a mixture. Also shows how soluble a substance is in the solvent
What is the stationary phase in paper chromatography?
Chromatography paper (filter paper)
What is the mobile phase in paper chromatography?
Solvent (ethanol or water)
How do you calculate the Rf values in paper chromatography?
Rf= distance travelled by substance B / distance travelled by solvent A
How to test for carbonates? (Anion)
Dropping a pipette to add a few drops of dilute acid containing mystery substance.
Then connect test tube to a test tube containing limewater. If carbonate ions present it will go cloudy
How do you test for sulfates?
Use a pipette to add a couple of drops of dilute hydrochloric acid and barium chloride solution to a test tube containing mystery solution.
If sulfate ions are present, white precipitate will be formed (s)
How do you test for halides?
Add a couple of drops of dilute nitric acid followed by a couple of tops of silver nitrate solution to mystery solution
Chloride- white ppt
Bromide-cream ppt
Iodide-yellow ppt
What is the purpose of flame tests?
You can identify metal ions present in substances
What do lithium ions produce?
A crimson flame (Li+)
What do sodium ions produce?
A yellow flame (Na+)
What do potassium ions produce?
A lilac flame (K+)
What do calcium ions produce?
A orange-red flame (Ca2+)
What do copper ions produce?
A green flame (Cu2+)
What affects wavelengths emitted by an ion in flame emission spectroscopy?
- charge
- electron arrangement
What are advantages of using machines?
- very sensitive and can detect tiny amounts of substances
- very fast and tests can be automated
- very accurate
Why is flame emission spectroscopy more useful than flame tests?
They can identify different ions in mixtures and not just single metal ions
How can flame emission spectroscopy be used to produce a line spectrum for an element?
- a sample is placed in a flame. As the ions heat up, their electrons become excited
- when electrons drop back to their original energy levels, they release energy as light
- the light passes through a spectroscope which can detect different wavelengths of light to produce a line spectrum
