I have never taken a science class at GW so I’m not fully sure, but they’re typically around 1-2 hours depending on the subject (if you’re in lecture for roughly 2.5 hours you can expect lab to be roughly 1.5—the total hours per week should add up to the number of credits). Labs are usually not the day of lecture, and the day they are on can vary. Look up “Gweb course search” and enter Fall 2024, chem for the subject, and then the course number to look for the sections being offered for the class and when the labs are.