For Kovac's reagent what concentration of hydrochloric acid do you use?

Answer 1

Most recipes just specify 'concentrated' HCl. That could mean 32 % or 37 %. One or two specify 32 %. Now, HCl 32 % w/w = 37 % w/v and HCl 37 % w/w = 44 % w/v, and since the HCl in Kovacs Reagent is mixed 1:3 (by volume) with isoamyl alcohol, the final concentration of HCl will be 9.25 % w/v or 11 % w/v respectively. Further, some recipes specify a 1:3 mixture by mass - resulting in proportionally much less HCl. So it's not critical. I'm using 32 %.

Answer 2

Kovac's reagent typically contains 7.5% hydrochloric acid.