alkaline, alkali, lye, salt
鹼 centers on chemically basic substances: alkalis, lye, and salts that are alkaline in nature. The meanings are tightly linked through the shared chemical property.
鹼 combines 鹵 (salt) with 僉, which likely contributes the sound. The character was used historically for alkaline substances derived from salt.
The left side 鹵 is the salt radical, and the right side 僉 looks like a complex chemical apparatus. Picture extracting lye from salt using this intricate setup.
For ケン, imagine a chemist named Ken working with alkaline solutions: Ken -> ケン, and he carefully handles the lye.