C14 Chemical Analysis Flashcards
What do impurities do to the melting and boiling points of a sample?
Lower the melting point and raise the boiling point
What is a formulation?
Mixtures that contain specific measured quantities of elements/compounds to ensure efficacy in their usage
What are the 2 phases of chromatography?
-Mobile- molecules can move
-Stationary- molecules can’t move
How can Rf values be calculated?
Distance travelled by the the substance/distance between solvent front and baseline
What conditions can affect the time a substance spends in the mobile phase?
The type of solvent used
What is the stationary phase in paper chromatography?
The chromatography paper
(chromatography) The longer a substance spends in the _______ phase, the further it moves up the paper
Mobile
What is the test and positive result for chlorine?
Holding damp litmus paper up to the reaction vessel- bleaches it white
What is the test for hydrogen?
Produces a ‘squeaky pop’ when a lit splint is held to it
What is the test for oxygen?
Relights a glowing splint
What is the test for carbon dioxide?
Turns lime water cloudy when bubbled through it
What is lime water?
Calcium carbonate solution
How can a sample be tested for metal ions using a flame?
Dip a nichrome wire in hydrochloric acid and hold it in a blue flame in a Bunsen burner. Withdraw it when no colour is produced. Dip into the sample and hold it into the flame to observe the colour.
Why may testing for ions by observing the colour of the flame they produce be unreliable?
If the sample contains multiple metal ions, the flame colours of some may be obscured by the others.
What colour flame do lithium ions produce?
Red
What colour flame do sodium ions produce?
Yellow
What colour flame do potassium ions produce?
Purple
What colour flame do calcium ions produce?
Orange-red
What colour flame do copper ions produce?
Green
How can you test for metal ions using hydroxides?
Add a few drops of sodium hydroxide solution to the sample you are testing. If a coloured precipitate forms, you can deduce which metal was in the sample.
What are the products of a reaction between a carbonate and a dilute acid?
A salt, water and carbon dioxide
Describe how flame emission spectroscopy works:
A sample is placed in a flame, exciting the electrons in the ions. As the electrons drop back to their original energy levels, specific wavelengths of light are released. These pass through a spectroscope which show a line spectrum.
What are the advantages of using machines in chemical analysis?
-Very sensitive
-Accurate
-Efficient
What colour is a calcium hydroxide precipitate?
White
