{HEAD ~ The aqueous solution} of {TAIL ~ sodium} hydroxide, which is the heavier phase, contains most of the catalyst 
{ HEAD ~ The aqueous solution } of { TAIL ~ sodium } hydroxide , which is the heavier phase , contains most of the catalyst
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH