I'm going to go with the very simple answer here:
The lens does not change. The f/1.4 50mm EF lens has exactly the same focal length (and everything that goes with that) as your EF-S zoom lens set to 50mm.
The "crop factor" is not useful for comparing different lenses on the same camera. It's only useful for comparing lenses across different camera formats — which means different film or sensor size.
And then, because I can't help myself, I'm going to go a bit further. This seems like overcomplicated nonsense, but it's actually both pretty simple (it only seems complicated — honest!), and a reasonably useful tool to know about.
So, in case you want to chase things further, once you're definitely unconfused and clear about the basics, see:
Which give some depth and background. But still, remember, the answer to your question is simple: focal length is a property of the lens, and you can't change it without more optics.