MacBook 13" logic board part number

According to the serial number in the photo, it's a Mid 2012 13" MacBook Pro. That means it's either a 2.5 GHz i5 or a 2.9 GHz i7. iFixit has the i5 in stock, and Powerbookmedic has an i7:

MacBook Pro 13" Unibody (Mid 2012) 2.5 GHz Logic Board

MacBook Pro 13" (Mid 2012) 2.9 GHz i7 logic board

Sostituzione Scheda Logica MacBook Pro 13" Unibody metà 2012

EDIT: As wesley notes, iFixit also has an i7 logic board, which I missed. Oopsie, although it helped to trigger iFixit's new spam filter :-/

As you can see, this is not a cheap replacement, and it's not an easy repair. There are a couple of options worth trying before shelling out $400-600 for a replacement logic board.

First, make sure that the liquid cleanup you've done is thorough, and you've both removed whatever residue the liquid left behind and dried the liquid completely. iFixit has several guides for damage control after spills; even if the devices aren't the same, the principles apply to all electronic devices.

Liquid Damage Technique

Electronics Water Damage

Riparazione danno da liquidi iPhone

Next, there are certain items that you generally have to replace after liquid contact, including the battery and sometimes the MagSafe/DC-in board:

[prodotto collegato mancante o disabilitato: IF163-019]

MacBook Pro Unibody 13" and 15" MagSafe DC-In Board

Finally, a suggestion before extreme surgery: A check of the serial number at Apple's support site indicates that this laptop is covered under AppleCare Extended Warranty until April 19, 2016.

Normally, Apple doesn't cover 'accidents' such as liquid damage; that's why they put liquid sensors on the logic board, to bust you if you bring in a deadster and lie about why it died. But sometimes the Genius Bar will be generous, and absorb the cost of an uncovered repair for a sympathetic customer. I think it's at least worth trying to walk it into your local Apple Store, give them the sad story, and see what happens. At the very worst, they'll charge you about the same price for the logic board swap (parts and labor) that you'll pay just for the part on the outside. If the repair is done by the Apple Store, you'll get a 90-day warranty on the repair, and the existing warranty will remain in force.

It's at least something to consider.

Whatever course you take, please post back and let us know what happened; it gets the results on the record, and it gives us a sense of closure. If you try the Genius Bar trick, let us know whether they offer you some kind of deal; Apple's internal policies often change without announcement, and it's useful for those of us on the outside to know whether they're being generous or stingy.