What is the internal i2c address to CAT24AA16-D
That EEPROM has a size of 2048 bytes, which requires 11 bits to address.
The datasheet states:

Thus, it says the four most significant bits of the device/slave address byte are &quot;1010&quot;, and the next 3 bits are the 3 most significant bits of the memory address to be accessed, with the 8 least significant bits of the memory address to access in the next byte, as clarified here:

So, for example, if you want to access memory address 1365, 10101010101 in binary, the slave address byte would be 1010101X and the address byte would be 01010101. (Where X is the read/write bit).