Question: Almost all soft drinks like Thums-up, Pepsi, Coke are laced with phosphoric acid. Phosphoric acid/H3PO4 is extracted by a chemical reaction of sulphuric acid on calcium phosphate which forms phosphorous pentoxide. This chemical, when mixed with water, releases phosphoric acid. Why is phosphoric acid mixed with soft drinks?
Answer: This mild acid not only gives a tingling sensation to the tongue but also stimulates the taste buds to savour the flavor and sweetness of the soft drink. It also makes the soft drink a bit sour in taste. Iron oxide (rust) is also present as an element of phosphoric acid in various soft drinks which makes them ill-famed although they seem refreshing.