CHEMICAL ANALYSIS Flashcards
what is a pure substance
is something that only contains one compound or element and is not mixed with anything else
what can tell you how pure a substance is
the boiling or melting point
how can you test the purity of a substance
by measuring its melting or boiling point and comparing it with the melting or boiling point of the pure substance
the closer your measured value is to the actual melting or boiling point the purer your sample is
what will impurities in your substance do to the substance
it will lower the melting point and increase the melting range of your substance
it will also increase the boiling point and may result in your sample boiling at a range of temperatures
what are formulations
are mixtures with exact amounts of components
why are the components in a formulation important
each component in a formulation is present in a measured quantity and contributes to the properties of the formulation so that it meets its required function
why are formulations important in the pharmaceutical industry
eg by altering the formulation of a pill, chemists can make sure it delivers the drug to the correct part of the body at the right concentration
where can formulations be found in everyday life
cleaning products
fuels
cosmetics
fertilisers
the melting point of a sample of aspirin made by a student is measured as being between 128-132 degrees
the melting point and boiling points of pure aspirin are 136 degrees and 140 degrees
a) give two reasons why the melting point measured shows that the sample is not pure
b) suggest a value for the boiling point of the sample
a) the sample melts over a range of temperatures.
the melting point is lower than that of pure aspirin
b) any range or value above 141-200 degrees
what happens during a flame test spectroscopy
a sample is placed in a flame
the ions heat up and gain a lot of energy, when the electrons drop back to their original energy levels they transfer energy as light
the light passes through a spectroscope which can detect different wavelengths of light so each ion produces a different pattern of wavelengths and has a different line spectrum
the intensity of the spectrum indicates the concentration of that ion in solution
what else can flame emission spectroscopy be used on
it can work on mixtures which makes it more useful than flame tests
what instrumental analysis can scientists use instead of conducting tests
flame emission spectroscopy
what are the advantages of using machines (flame emission spectroscopy)
very sensitive- they can detect even the smallest amount of substances
very fast and tests can be automated
very accurate
why might it be necessary to use flame emission spectroscopy instead of a flame test to identify metal ions
flame emission spectroscopy can be used to identify the metal ions in mixtures whereas flame tests can only be used for substances that contain a single metal ion
