Polyprotic Acids

[anthropos]

Yo, I am a 17 year old student and one day I saw this question in my textbook.

 

"Acids are added to cola drinks to lower the pH to about 2.5 to impart tartness. Show that a cola that contains from 0.057 to 0.084% of 75% phosphoric acid (H3PO4), by mass, meets this pH requirement. "

 

Can somebody explain the "0.057 to 0.084% of 75% phosphoric acid (H3PO4), by mass"? I don't quite get it.

[insane_alien]

okay, say you have 1 gram of of 75% phosphoric acid by mass. that means that 0.75grams is pure H3PO4, the rest is water.

 

the 0.057 to 0.084% refers to the amount of 75% phosphoric acid in the drink. compared to the mass of the drink as a whole.

[anthropos]

ooh thanks =)