Start with a stock solution of 37% HCl acid and produce 500 g of 5% HCl acid.
37% would be 10.1M HCl. 5% of 500g is 25g, which is 1.37M.
Using C1M1=C2M2 I calculate that I need to use 67.8g of stock to create my desired dilution. Is that correct?
10.1M*Xg=1.37M*500g
Xg = 685/10.1
Xg = 67.8 g