Is there a formula or way to determine whether an acid is a strong one or a weak one without conducting experiments in real? I know the common strong and weak acids but if a mineral acid like $\ce{H3BO3}$ springs up, I can't actually tell whether it is strong or weak.
Also can I justify in chemical terms why $\ce{H2SO4}$ is a strong acid but $\ce{H2SO3}$ a weak one?
Why is $\ce{HNO3}$ a strong acid whereas $\ce{HNO2}$ a weak one ?

http://catalog.flatworldknowledge.com/bookhub/2273?e=ball-ch12_s04

The above link shares a list of strong and weak acids but fails to state why one acid is weak while the other strong.
Is there a formula or way to determine whether an acid is a strong one or a weak one without conducting experiments in real?


Yes, there are ways to determine whether an acid is strong or weak without going into the lab yourself. That being said, someone must still go into the lab. 

The most straightforward way would be calculating ΔG for an acid-base reaction. Remember, a negative delta G means that a reaction is spontaneous. Since strong acids have a Ka > 1, their ΔG values should be negative.