This looks like the reaction used to determine, or abstract, halides.
Silver nitrate is used to abstract halides and determine what the halogen atom is in the ethyl molecule. The reaction is often done in a lengthy process, and has a handful of results; if the ethyl contains bromide, the result will be a creamy precipitate that enters a clear solution with ammonia
The reaction is usually in a few parts.
- The halogenoalkane (in this case bromoethane) is warmed.
- Sodium hydroxide, ethanol, and water are added. This will dissolve everything into a solution, and the hydroxide ions of the sodium hydroxide will cause the halogen to ionize into the solution as the hydroxide substitutes into the ethyl.
- Nitric acid is added to bond with the free OH ions.
- The silver nitrate is added, which will bond in a substitution reaction with the bromine. Because the bromine is a -1 ion, and the silver is a +1 oin, this will occur in a 1:1 ratio.
- The silver bromide will precipitate out as a pale cream, and can be dissolved into ammonia for confirmation.
In the end, your reaction will take place in a 1:1 ratio. All of the ions in the reaction are of a 1+/- charge, so the reaction is easy to balance.