As you noted, the 1.5 percent is PER OUNCE .... and this is on TOP of the 8% sales tax that already applies to soda in Pennsylvania. Soda is classified as food, which is tax exempt in some states, but not in Pennsylvania.
The 1.5% per ounce tax adds 18 cents to the cost of a can of soda, $1.08 for a six-pack or $1.02 for a two-liter bottle.
Link: http://money.cnn.com/2016/06/16/pf/taxes/philadelphia-passes-a-soda-tax/index.html
I live in PA - food is tax exempt here