Chemistry Help

[Belgarion]

I cant get these questions, any answers would be appreciated:

1. HCOOH and CH3COOH have Ka vaulues iof 0.00018 M and 0.000017 M respectively.

calculate the pH of 0.01 M of HCOOH

calculate the concentration of CH3COOH need to produce same pH as first part


2. At 5 degrees, the concentration of OH ions in a pure water sample is 0.00000004 M

calculate concentration of hydronium ions

calculate value of Kw

Calculate pH of pure water


3. CO2(g) + 2H20(l) double arrows H30+ + HCO3-

Concentration of C02 is 0.000013 M and pH is 7.4

calculate concentraion of H30+ ions

Calculate Ka assuming [H30+]=[HCO3-]



4. A certain weak acid has a Ka of 0.00002 M.     HA + H20 double arrows H30+ A-

Calculate pH of 1M solution of acid

Small amount of solid salt with formula NaA is added until it dissolves. Concentration of A- ions is 0.0021M. Calculate new pH