Question

what reactions can be observed (if any) when these solutions are mixed?

H2SO4 + Na2CO3

BaCl2 + Na2CO3

BACl2 + Pb(NO3)2

HCL + KOH

Answer 1

each one of those pairs is the front half of a double displacement reaction. Follow the pattern that all double displacement reactions have, and use a solubility table to see if one of them makes an insoluble precipitate

Answer 2

H2SO4+Na2CO3=>Na2SO4+H20+CO2
Similarly do the second and the third equation to get a salt,water and a gas and balance if required.
last equation shows an acid and a base so we know that acid+base => salt+water ... correct?? so similarly do it.. okay?? @HannyMacey ...

Answer 3

Thankyou @JFraser and @ashley007 for your responses, I appreciate it. although I was looking for the visual observations that could have been made, your responses helped in another part of my work, cheers (: