Chemistry problem!!!

1. Sulfuric acid (H2SO4), a strong acid, is the acid of choice for batteries. The reason a strong acid is used in batteries is because the sulfate in this strong acid (SO4) has relatively less affinity for its hydrogen ion that some of the weaker acids. Giving off the hydrogen ion can form H3O+ and 2 electrons. This is how the charges are stored in a battery. When the battery discharges, the acid is turned into Lead Sulfate and water.

Phosphoric acid (H3PO4), on the other hand, has a strong affinity for its hydrogen. So, it's considered as a weak acid. The phosphorous (PO4) has a strong affinity for its hydrogen, so that makes it unsuitable for use as a battery acid. However, it is useful as a buffer to keep the pH of a solution stable because of its high affinity for hydrogen ions. Remember that high hydrogen ions in a solution makes the solution acidic?

2. Instead of phosphoric acid, there are other acids that are not harmful to human. For example, vinegar is made of Acetic Acid. That's why vinegar is sour. Also, many fruits like lemon and oranges contain a lot of Citric Acid. These are acid that you consume all the time. Carbonic Acid is yet another acid that can be found in some carbonated drinks.

3. All of the above mentioned acids (Citric Acid, Carbonic Acid, Acetic Acid ) can be used to substitute phosphoric acid...well, I wouldn't use Acetic Acid unless I want my Coke to taste like vinegar. HAHA! :)

Good Luck!

i do not understand your answer for Q1 and Q2, can you describle it more details?

1)Battery acid is con.H2SO4 sulphuric acid.
2)Most organic acids such citric acid in lemon, acetic acid in vinegar, hydrochloric acid in stomach generating by the cells there, uric acid in urine, lactic in milk. Some are in food, some are produced to digest food, some are the by-product after digestion & etc.
3)Use citric acid & carbonic acid.