Question

Jason and Susan got a new freshwater aquarium. The pH of their tap water is 7.8 and the apistogramma fish they would like to keep prefer a pH between 5.5 and 6.5. The store wants to sell them a relatively expensive bottle of a product called “API pH Down”. They think distilled white vinegar from the dollar store will be just as effective in bringing the pH of their aquarium down.

Describe an experiment that would provide strong evidence for evaluating this claim.

Answer 1

API pH Down has sulphuric acid which a strong acid, having a pH of ~2.75, as we know acids have a pH lower than 7, therefore, we use an acid to lower down the pH of the system.

distilled white vinegar has a pH of ~2.4. so this is much suited to bring down the pH of the system.

the pH of the sulphuric acid and white vinegar can be observed using a pH paper which turns to pinkish red color when comes in contact with acids or solutions having pH less than 7. it turns pink for both sulphuric acid as well as white vinegar. this will show that both are acidic and hence will bring down the pH of the system.