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:

• Is the kit lens focal length specified for APS-C or FF?
• What is the difference between EF and EF-S lenses?
• Does my crop sensor camera actually turn my lenses into a longer focal length?
• What is crop factor and how does it relate to focal length?
• Why do we talk about focal-length when frame sizes are different?
• Why do Full Frame lenses and crop body lenses exhibit the same crop factor when used on a crop body camera?

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.