what is the concentration of hydroxide if the pH is 11.3. i dont have a calculator to do this

pH = negative log₁₀ of the hydronium ion concentration in a solution

concentration of hydroxide = concentration of hydronium @ pH = 7

Multiply 7 by 2 (so when the 2 are added up, it equals 14)

Subtract 11.3 from 14, that is the hydroxide concentration

I trust you can do the above subtraction on your own.