posted by Steve .
mol KHP = (0.7719)(mol KHP/204.2g KHP) = .0038mol
Since this is a titration then the moles of NaOH = the moles of KHP
M = mol/L
M = .0038mol/02637
M = 0.01441
Two minor problem.
First, you have rounded 0.7719/204.2 incorrectly. You have 4 significant digits in both the numerator and denominator; therefore, you are allowed 4 s.f. in the answer. Unless the answer is 0.003800, your rounding makes the answer wrong. And it isn't 0.003800. I get 0.003780.
Calculator tip #1--To get around the rounding errors, I don't copy the answer down and start over when I divide by the 26.37 mL of NaOH. I just leave that number of 0.0038781175 etc etc to nine places in my calculator. Not only does it save time, because I don't need to copy it and re-enter it into the calculator, but it preserves the digits, whatever they may be. All of them may not be s.f. but that really doesn't matter. Whatever the number of s.f. I know they are in the calculator.
Second--I think the division is off by a factor of 10. I get 0.1433.