A student combines solutions of silver nitrate, AgNO_3, and sodium chromate, Na_2CrO_4, and observes that a reddish-brown solid forms. Based on this observation, what type of a reaction can the student infer has occurred?

1 Answer
anor277
Jan 18, 2017

A metathesis, or partner exchange reaction has occurred:

Explanation:

2AgNO_3(aq) + Na_2CrO_4(aq) rarr 2AgNO_3(aq) + Ag_2CrO_4(s)

Most silver salts are quite insoluble; the nitrate is an exception. Silver chromate precipitates from aqueous solution as a brick red precipitate.

![https://sp.yimg.com/ib/th?id=OIP.M7812ed9b7649fe58f150080fe28f60aeo0&pid=15.1&w=79&h=118&p=0](useruploads.socratic.org)

The reaction could also be called a "precipitation reaction". This particular reaction is the basis of the "Mohr titration", for quantitative analysis of silver ion.

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