Question

Do these reactions form precipitates?
NaCl + NaBr
NaCl + Na2CO3
NaCl + BaCl2
NaCl + HCl

Thank You

Answer 1

laman, the way to approach these problems is to understand what anions and cations are most often insoluble. So All alkali metal salts are soluble.
You will want to remember which chlorides, bromides are insoluble (Ag for example form precipitates)
All nitrates are soluble.
I would find a good book and look at these rules systematically.

Answer 2

Perhaps this chart can help you a bit

Note:
if the two compounds are soluble, they may form soluble or insoluble compounds, depends on which ions are present.
For example: NaCl is mixed with NaHCO3, the resultant mixture is still soluble
=> no precipitates
NaSO4 is mixed with BaCl2 (both are soluble salt), precipitates are formed since one of the resultant compounds (BaSO4) is not soluble .

That means you need to consider the combination of the ions.