Tries from Hamish Watson, Mark Bennett, Matt Fagerson and Sam Johnson saw Gregor Townsend's men to a confidence boosting victory.
Blair Kinghorn and Ross Thompson contributed off the kicking tee while for Argentina their points arrived via two penalties from Emiliano Boffelli.
Scotland had trailed 6-3 before Watson gave them a narrow advantage three minutes before the break.
But Townsend's side took control in the third quarter of the match, scoring 21 unanswered points in the second half to tie the series at 1-1.
The series will now be decided in next Saturday's third game in Santiago del Estero.