Question

how many grams of tris and tris Hcl are needed to make up 500ml of 1m tris buffer with a pH of 0.8?

Answer 1

I assume you mean 1 M and not 1 m. M is molar; m is molal.
You need two equations.
equation 1 is
pH = pKa + log (base)/(acid)

equation 2 is
(base) + (acid) = 0.8 M

Use equation 1 and solve for (base)/(acid) then (base) = k(acid). Then plug that into equation 1 to find (base) and (acid). Convert molarities into grams per liter , then grams/500 mL.
Post your work if you get stuck.

Answer 2

Question makes no sense. pH of 0.8 or 8.0????

Answer 3

pH is 8.0

Answer 4

Here's a reference that's useful for tris systems...(remove the space between the h t, copy and paste => search)
h ttp://www.sigmaaldrich.com/Graphics/Supelco/objects/4800/4709.pdf