Why you say 'para tí' and not 'para tú'?

Answer 1

para = for para is a preposition

ti = you is a prepositional pronoun and therefore follows a preposition

tú = you is a subject pronoun and therefore does not follow prepositions; it serves as

a subject of a sentence as in: Tú hablas muy bien = You speak very well

Answer 2

After a preposition, you must used stressed pronouns, not nominative pronouns. For example, you say "a mí" instead of "a yo" or "para mí" instead of "para yo" or "de tí" instead of "de tú". The nominative pronouns are: yo, tú, él, ella, ello, Ud., nosotr@s, vosotr@s, ell@s, and Uds. The stressed pronouns are: mí, tí, él, ella, ello, Ud., sí, nosotr@s, vosotr@s, ell@s, and Uds. Since "para" is a preposition, the stressed pronoun must follow, so "para tú" transforms into "para tí".

Answer 3

"Para ti" is the correct prepositional phrase to use in Spanish to convey "for you." "Para tú" is incorrect because the preposition "para" requires the use of the object pronoun "ti" instead of the subject pronoun "tú."