chag

Hi everyone. I discovered this forum and I found it quite helpful. However, I'm still doubting whether or not to apply for a Chemistry PhD program on Fall 2014 in the US. I'm from Argentina and I'm maybe a month away from finishing my undergraduate studies in Chem. I've been going through a lot of PhD programs websites, trying to gather all the information I need. But I'm not certain about how real my chances are. GPA: I'm not quite sure how this works. We have a 1 to 10 grading system here in Argentina, and it doesn't matter how many credits correspond to each class (in fact, there isn't any credit system in my country. We have to pass a fixed amount of classes and that's it). Our academic performance is represented by the mean of all our grades. Mine is around 7.9 out of 10 (more like 7.95). Regarding the GPA, does the admissions committee evaluate the general GPA? Or do they pay special attention to field-related grades (If I take out Math and Physics grades, the mean would go up to 8.5 out of 10). Regarding exams, I feel pretty confident about the General and Subject GRE. I've done several practice tests. TOEFL exam, required for non-English speakers, is expected to be easy (not being cocky, it's just that I've been studying for these exams for a long time now). I've been involved in a research project for about 2 years. No publications yet, though. We're still working on that and may have something to be published next year, after the application deadline. I might not be the first author. The LORs I'm expecting to have are positive, but no that special. Finally, I've had a position as a TA for a year. Taking all this into account, which kind of institution should I aim for? I now my grades are not good, but does anything else compensate that? Also, I'm about to turn 25. Should I postpone the application until I have this paper published? Is there such thing as 'too old to apply' for the admissions committee? I apologize for the length of the post. Any help or comment would be much appreciated.