[wiped_out]

I'm not quite sure how to go about solving this one:

Gastric Juice is essentially a solution of HCl and the enzyme pepsin. It has a normal pH in the range of 0.3-1.2, with the lower figure leading to hyperacidity. Relief from hyperacidity is provided by antacids, such as Al(OH)3. What mass of Al(OH)3 must be used in an antacid tablet designed to increase the pH of 500 mL of gastric juice from 0.3 to 1.2?
Al(OH)3 = 78.0 g/mol

the answer is 5.7 grams, not sure how to get there though.

[Borek]

Starting with reaction equation won't hurt.

What is initial concentration of the acid?

What is final concentration of the acid?

How much acid has to be neutralized to change pH?

[wiped_out]

So...

3HCl + Al(OH)3 => AlCl3 + 3H2O

(10^-0.3 x 0.5) - (10^-1.2 x 0.5) = 0.219

0.219/3 = 0.73

0.73 x 78.0 = 5.69

[Borek]

Wasn't that hard.