The science experiment gone wrong

A classroom of students in a highschool science class had mixed chemicals together as part of an experiment, but one pair of students mixed the wrong chemicals and it caused a reaction that had slowly spread throughout the world over time. The reaction was similar to that of acid in a way. When you wake up, you wake alone in your apartment, the outside world's empty, aside from a few stray animals, trash and debri is everywhere. You have a bit of food in the house but it's mostly gone, there's plenty of tap water though.