Chemistry - Volumetric analysis, back titration - activity 10
Volumetric analysis, back titration - activity 10
Back titration can be used to determine the nitrogen content of food. The
nitrogen is first converted into ammonia, NH3, in aqueous solution. Ammonia
is a weak base and is most accurately analysed by addition of an excess of
a strong acid, followed by titration of the excess acid with a strong base.
The following partially annotated flowchart shows key data collected in
the analysis of the amount of nitrogen in a particular food sample.
Using the information supplied in this flowchart:
(a) Write balanced equations for two acid-base reactions involved in the
(b) Calculate the _n_(HCl) reacting with the NH3 produced from the food
(c) Determine the percentage, by mass, of nitrogen in the food sample.
Answer (a) and (b)
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