i usually carry a couple of powerlink things i case i snap a chain when i'm out. I used the pair i had at the weekend and was wondering if i could just use the powerlinks from an old worn chain as an emergency instead of buying a few new ones?

Or will the chain jump or catch on the chainrings if i have put a worn link into a newish chain?

I never bin them & just use what's lying around

Is this sram your talking about ?
If so you'll be fine i'm currently running 2 on my orange as the chain snapped ! (whilst riding the climax on my own ) 🙄
I am however changing it this week but it has been fine for around a month of riding like it . I always keep the speed links they are very strong