Changing partition in Terminal

I have two partitions in my drive, namely System and Data. I wanted to change from loong$ to Data.

Using terminal, I did a mount. Saw the volume Data.

But when I did a cd, error. Anybody can help?

Last login: Mon Nov 7 04:40:24 on ttys000
unknown_f0-b4-79-13-f7-d4:~ loong$ mount
/dev/disk0s2 on / (hfs, local, journaled)
devfs on /dev (devfs, local, nobrowse)
/dev/disk0s3 on /Volumes/Data (hfs, local, journaled)
map -hosts on /net (autofs, nosuid, automounted, nobrowse)
map auto_home on /home (autofs, automounted, nobrowse)

unknown_f0-b4-79-13-f7-d4:~ loong$ cd/volumes/data
-bash: cd/volumes/data: No such file or directory

unknown_f0-b4-79-13-f7-d4:~ loong$ cd\
> cd/volumes/data
-bash: cdcd/volumes/data: No such file or directory
unknown_f0-b4-79-13-f7-d4:~ loong$