We are upgrading our powderoom sink. Becuae the plumbing will be exposed we have purchased a nice chrome 1-1/4 ptrap - the end of which has no threads. The pipe coming our of the wall is PVC - again no threads. As well, the PVC is 1-1/2 so it is bigger than the ptrap. Are there any connectors that I can use to make the chrome ptrap fit the plastic PVC pipe?

Purchase a chrome escutcheon ring, sized to fit 1 1/2 PVC and a 1 1/2" PVC female trap adapter fitting.

Cut PVC pipe coming out of wall a few inches from wall. The further from the wall the better in case you have to make changes at a later time. Slip on escutcheon ring. Glue trap adapter on drain pipe. The adapter will come with two nylon compression rings. One for a 1 1/2 trap arm and one for a 1 1/4" trap arm. Slip trap arm into trap adapter and tighten nut.

You may have to cut the trap arm to length. The trap arm should go well into the adapter but not so far as to hit the back of the tee (if there is one) in the wall and thus restrict the flow of water.

Adapter and escutcheon ring available at any hardware or home improvement center. Do not confuse the trap adapter with a slip (glue) to threaded pipe adapter. They appear to be the same but are not quite the same internal size.

You can do as Hkstroud suggested, for sure, or go to a local plumbing supply store and order the 1.5" PVC x chrome PTRAP for lavatories... ;)

See images below.

Most of these traps come as 1.5" with the option to reduce to the 1.25" for the lavatory sink at the final nut at the trap (1.5" x 1.25" chrome nut/washer).

Good luck!

Mark