Of course, the sodium remains in the liquid also, but that only is a spectator ion, so I did not mention it.
To be more precise, if you add NaNO3 to concentrated HCl, then you'll get some white precipitate of NaCl (and also left over NaNO3). In solution you will have the following ions:
and you will of course have water.
The H(+), Cl(-) and NO3(-) will slowly react, forming Cl2, NOCl and H2O. So, after some time, the liquid also will contain molecules of Cl2 and NOCl besides the ions, mentioned above.
Is CaO really interesting? I would certainly not add it to your collection of chems as a starter. Even now, while I'm doing chemistry for quite a few years already and have a few hundreds of different chems, I still do not have CaO. There are more interesting ways to spend your money (besides the chems I mentioned earler, a very good one is a mix with 5% ethanol, some CO2 bubbles in it, and a tasteful golden yellow aroma
Many salts exist in multiple forms. Hydrated forms and anhydrous forms. CuSO4.5H2O is copper (II) ion, with 4 H2O-molecules coordinated to it, and one H2O molecule coordinated to the sulfate ions. These compounds are very different. Many hydrates are true ionic compounds, such as CoCl2.6H2O, CrCl3.6H2O, NiSO4.6H2O, while the anhydrous compounds are not true salts but are strongly covalent. Their chemical properties are very different and they also look very different:CuSO4.5H2OCuSO4NiSO4.6H2ONiSO4CoCl2.6H2OCoCl2