My daughter is addicted to this site, and this is having an adverse impact on her studies.
What methods are there to prevent her accessing Facebook in Google Chrome?
Usually you can do this in your router if there is a firewall (blocking the traffic incoming AND outgoing from/to the IPs). Usually you can also select which internal IPs are blocked for outgoing so you could block only her computer from accessing the site. Be sure to assign always the same IP to her (using MAC address in DHCP). Anyways, nothing (except removing her ethernet cable :) ) is a 100% solution as she always can use a proxy to access what she wants... You can also install a proxy and monitor/block traffic based on IPs and keywords and block all the proxies you can and update the list regularly but... this is a lot of work, not 100% secure, not really a solution for a home and I think a serious talk or a few talks and maybe some small threats about removing all internet access should solve the problem better because she probably have friends with computers too... so even if you succeed, she will find a way to access anyways.
You can install BlockIt, which is a plugin designed for Chrome that allows you block certain domains.
Install it, create a password and then add Facebook to the list of domain names to block.
To unblock it, use your password to login to the BlockIt interface and allow it again.
You can also add a custom message that will appear whenever someone tries to access a blocked domain, maybe telling her to stop wasting her time on Facebook and get some homework done!
If talking to her fails...
I'm not sure how to do this specifically in Google Chrome. There might be an extension that can be installed that will block specified sites (which would obviously need to be password protected to prevent it being bypassed).
But if you were to block Chrome, what is stopping another browser being used?
You could block a specific website on the WHOLE PC by editing the Windows HOSTS file. You can then direct all requests to facebook.com to an alternative IP Address (eg. 127.0.0.1 - localhost - in other words nowhere!). Although depending how tech savvy your daughter is this can be changed back!
To block facebook.com (and other social networking sites) on your ENTIRE NETWORK you can change the DNS settings in your router to use an alternative, such as OpenDNS. If you then sign up to OpenDNS you can then block all sorts of websites by category. This is probably the most secure way if you are accessing the internet through a router as you can password protect the routers control panel to prevent changes to the DNS.
You might consider allowing access to facebook at certain times of the day (a healthy compromise?), which I think OpenDNS might allow you to do as well?