Is changing a att chip from iphone to moto x againts the contract?

I want to switch to a moto x but my contract ends in december can i transfer my chip to a moto x. I have a iphone 5

No it's not against contract.

However, do be aware that if you're not up for an upgrade yet, that you'll be paying full retail price for that Moto X (instead of those lovely $99 or $199 prices, you'll be paying those $599 prices for the phone)

No its not.

If you have a network free iphone means, you will be able to swap your chip from Moto X phone to iphone.Locked means, you will need to unlock your phone. For unlocking you can approach your service provider or else try to buy an unlocking service from any one of the online unlocking service provider like http://www.mobile-unlocker.com/apple-iphone-5/rs5wp9/