/dev/sda2/chroot does not exist. /dev/sda2 is a file, not a directory. More precisely, /dev/sda2 is a device special file representing a block device, in this case being the second partition on an SATA-connected storage medium.
One always mounts a block device on a directory — or “folder”, in Microsoft and Apple speak. And then this directory is what you chroot into.
