Si vas tan deprisa por el pasillo, vas a chocar con alguien.

They are two different uses of ir:

• si vas tan deprisa... = if you go / if you walk / if you move so fast...
• vas a chocar... = you are going to bump into...

So the first vas is the main verb to go / move, and the second is part of the near-future structure ir a + infinitive.

This is a very common real-condition pattern in Spanish:

• Si + present, present or ir a + infinitive
• Example: Si estudias, apruebas / Si estudias, vas a aprobar

In this sentence, the speaker is talking about a likely real consequence:

• If you go that fast down the corridor, you're going to bump into someone.

Spanish often prefers ir a + infinitive in everyday speech instead of the simple future (chocarás).
So vas a chocar sounds natural and conversational.

Yes. That is also correct.

• vas a chocar = very common, everyday, immediate-sounding
• chocarás = also correct, a bit more straightforwardly future

Both mean basically the same thing here. In normal spoken Spanish, vas a chocar is often more common.

Tan means so in the sense of to such a degree.

• tan deprisa = so fast
• muy deprisa = very fast

In this sentence, the idea is:

• If you go so fast down the corridor...

That is why tan fits better than muy. The sentence is linking the degree of speed to the consequence.

Both can express the idea of fast / quickly, but they work a little differently.

• deprisa is an adverb: quickly
• rápido can be an adjective (fast) and is also often used adverbially in everyday speech

So you could say:

• vas tan deprisa
• vas tan rápido

Both are natural.
Deprisa may feel a bit more clearly adverbial, while rápido is extremely common in speech.

In Spain, deprisa is very common.

Both can be possible in some contexts, but por is especially natural when talking about movement along / through / down a place.

• por el pasillo = down the corridor / along the corridor
• en el pasillo = in the corridor

Since the sentence describes someone moving through that space, por is the better choice here.

Chocar con alguien means to collide with someone / bump into someone physically.

Here it does not mean the English idiomatic run into someone meaning meet someone unexpectedly.
It means an actual physical collision.

• chocar con la pared = bump into the wall
• chocar con alguien = bump into someone

Yes. Alguien means someone / somebody, and it can follow prepositions:

• con alguien = with someone
• para alguien = for someone
• de alguien = from someone / of someone

So chocar con alguien is completely normal.

Because chocar here is being used as a normal non-reflexive verb:

• chocar con alguien = to bump into someone

You may sometimes hear reflexive expressions in some varieties or specific contexts, but for this sentence, vas a chocar con alguien is the standard, natural choice.

In this sentence, yes, a comma is normal:

• Si vas tan deprisa por el pasillo, vas a chocar con alguien.

When the if-clause comes first, Spanish commonly separates it with a comma.

If the main clause comes first, the comma is usually not used:

• Vas a chocar con alguien si vas tan deprisa por el pasillo.

Yes. The verb form vas tells you the subject is tú:

• (tú) vas

Spanish often leaves subject pronouns out when the verb already makes the subject clear.
So Si vas... naturally means If you go... or If you’re going...

Yes, absolutely. In context, vas can suggest movement such as:

• you go
• you’re going
• you’re walking
• you’re moving

Because the sentence includes por el pasillo and tan deprisa, the natural idea is physical movement down the corridor.

Deprisa is especially common and natural in Spain. In many parts of Latin America, speakers may more often use:

• rápido
• rápidamente

But deprisa is widely understood everywhere.

Since you’re learning Spanish from Spain, tan deprisa is a very good phrase to know.

Yes. Even if the Spanish literally says go so fast, a more natural English translation may use:

• run
• rush
• go that fast
• move that quickly

That depends on context. The Spanish itself does not specifically say run (correr), but it strongly suggests rushing.

Yes. Pasillo usually means corridor / hallway / aisle, depending on context.

For example:

• in a house, school, or office: corridor / hallway
• in a shop or plane: aisle

In this sentence, corridor or hallway is the most likely meaning.

Yes. It sounds like a warning or caution.

The speaker is saying that the person’s current behaviour will probably cause a result:

• If you go that fast down the corridor, you’re going to bump into someone.

So it is not just neutral description; it carries a clear be careful feeling.