[stephenson]

    I need to understand the products for each reaction, and name each one as gas, precipitate, or water... I know it should be easy but my teacher doesn't make any sense!

____ 1. HBr(aq) + KOH (aq) -> ______________          A. gas
____ 2. HNO3 (aq) + Na2aco3 (aq) -> __________       B. precipitate
____ 3. NaI (aq) + Pb (C2H3O2) 2 (aq) -> __________     C. water[/tt]

[Arkcon]

Well, I agree, pretty crappily written question.    Well, lets see what reactions you can do for us.

[Kyle1990]

HBr_aq + KOH _aq--> H₂O_(l) + K⁺_aq+Br^-_aq

This is a simple double replacement. Hydrogen ion replaces potassium ion to form water and KBr (which dissociates in water and exists as K⁺ and Br^- ions, as does everything in the equation except water)

2HNO₃(aq) + Na₂CO₃(aq)-->H₂CO₃(aq) + 2NaNO₃(aq)
For this reaction, also a double replacement, hydrogen combines with the carbonate ion to form carbonic acid. This acid is extremely unstable and immediately breaks down into carbon dioxide gas and water. This is what happens when you open a can of pop.

NaI(aq) + Pb(CH₃COO)₂(aq)-->PbI₂(s) + NaCH₃COO

It is an absolute must to learn the solubility rules in order to write chemical equations. All halogen salts of lead are insoluble