Devard 's alloy is an alloy of copper , aluminum and zinc (50%, 45% and 5%, respectively). It is well ground into powder. They are used in analytical chemistry as a reducing agent for nitrates and nitrites in ammonia , etc.
In ionic form, the proceeding reaction can be written as follows:
![{\ displaystyle \ mathrm {3 \ NO_ {3} ^ {-} + 8 \ Al + 5 \ OH ^ {-} + 18 \ H_ {2} O \ longrightarrow 3 \ NH_ {3} +8 \ [Al ( OH) _ {4}] ^ {-}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/571bd44ce8f999bf73c8ee9971081ddf5cd7d63b)
The alloy was described in 1894 by an Italian chemist named Arturo Devard , so it would be more correct to call the alloy "Devard's alloy", but historically the "wrong" name stuck.