I'll call bs at 5'5 125 being able to curl 50lbs of anything remotely productive.
Doing a halfassed rep 5 times isn't going to do anything but pull a muscle or tendon.
You should stand with your back flat against a wall, and curl from your arm flat all the way to your shoulder, nice and slow with no rushing to maintain momentum, same thing coming down.
If you can do that 5 reps, hell even 2 reps at that weight I'd be very impressed.
