HCl

if I want to make 4% acid from 20% HCl, I make 20% by adding 4 equal parts of distilled water. So 1 part acid 20% and 4 parts water so I get 4% acid ??
thanks for the help!

Member CLO2 has an info page you should visit. If you go to her profile , right under her pic is a link to her site.
me, i bought food grade HCL 36%.  So I wanted 4%. I used 9 parts  8 parts was 800 ml of distilled water and 100 ml of the 36 % hcl.  I learned this from a video I watched by one of Mark Grenon's sons.   He had 20 % hcl , so he used 5 parts.  400 ml water and 100 hcl. So no matter what % hcl you have you divide it by the % dilution you want. In our case 4
 

endmemo.com/bio/dilution.php

Use the 4th calculator down the page. 

 

Always acid to water, not the reverse.