Layover
 

I'm leaving from Newark to Barcelona with a layover in Zurich. I'm flying on one ticket, will this be enough time? I'm confused if I'll have to go through passport control in Zurich or if I can go straight to my transferring gate.

<"will this be enough time?">

Will WHAT be enough time?

Sorry! 40 minutes

What airlines? Checked luggage? Does the US-ZRH airline say the checked bag will be checked through or will you have to retrieve it in ZRH and recheck?

I'm flying Swiss air. I'm checking one bag, but I'm not sure whether it's going through to Barcelona or if I have to recheck it.

We just did this - to Florence not Barcelona - and Zurich is a REALLY easy airport to navigate. You will go through Passport control but your bag should be checked through to Barcelona. If your original flight is on time you should have time - but don't meander !
If you are flying Zurich to Barcelona on one of their smaller planes you will meet at the gate and then take a bus out to where the smaller planes are.

Swiss is also good about holding the smaller planes of they are waiting for several people on a connecting flight of their own - n promises but they do this more often than other airlines.

Yes, if both legs are on Swiss and - as you state - it is on one ticket, they will make it possible for you to get there. Still, it will help if you can grab your things before the seatbelt sign comes on for landing, and have the things under the seat so you can stand up and walk towards the front of the plane immediately when the seatbelt light goes out, as far as you get before everybody blocks your way by standing and opening the overheads.

Your bag will be checked all the way through to Barcelona. I have made a 40-minute connection in Zurich and made my flight with no time to spare and even got my bag, but I have to say it was a harrowing experience. My flight was 10 minutes late landing, and we had to run at some points to get to our next connection (you may have to change terminals).

As @newtome says, Swissair prefers its passengers to make their connections, and they typically hold flights for a few minutes to accommodate all the passengers, something I didn't know on my way to Berlin. But I'd urge you to get a seat near the front of the plane and be prepared to move quickly. If you don't make the connection, you will be put on a later flight, but you might be delayed several hours.

It looks like Swiss has 3 to 4 non-stops daily from ZRH to BCN.

7:10
12:20
17:20
21:05 (some days)

so if you miss your scheduled flight then the next available flight is 5hrs later.

If you have everything on one ticket I would not worry at all. Zurich is also a beautifully run airport.