:-)
calculate the buffer ph of ch3cooh/ch3coo- buffer solution with an equal molar concentration of ch3 cooh and ch3coo-. given the ionization constant of acetic acid, ka is 1.73 ' 10-5

is it -4.76, -5.24, 5.24, or 4.76?

We can solve this problem using the long hand solution, wherein we 1 by 1 analyze the different equilibrium reactions or by simply using the Henderson Hasselbach equation. The equation is 

pH = -log(pKa) + log (salt/acid)

since the acid and the salt have the same concentration, the log (salt/acid) term is equal to zero. 

thus 

pH = -log(1.73*10-5)
pH = 4.76

please be careful with the negative sign 

Nonmetals usually react by gaining electrons