Casting a spell with every selected unit

Unfortuantely not. Each casted spell requires it's own command. Your easiest way would be to hold the Shift Key, press C, mouse click 13 times.

There's a technique called "quickcast". If you set the "cast spell" hotkey (default: click left mouse button) secondary hotkey to [C], then you can press and hold [C] to cast this quickly.

Since Zerg has ravagers that cast Corrosive Bile also with [C], you can use this to cast corrosive bile quickly, too.