Chemistry

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A student titrates 50mL apple juice and reports the following in the titration to the phenolphthalein end point with .1011M NaOH

A)What is the concentration of the total available acid in moles/L of the apple juice?
B)A drop is .05mL, what will be the percent error if the final reading is 2 drops past the actual endpoint?
C)What is the percent error in the result if the volume of the juice titrated was actually 51mL?
D)If the pH of the pure apple juice is 4.0, what is the Ka of the acid?

• Chemistry - ,

Do you have some idea about how to do some of this?
A. moles NaOH used = M x L.
moles acid = same as moles NaOH.
Then moles/L = moles acid/0.05.

B. The easiest way to do this is to add 0.1 mL to the volume and recalculate the molarity of the apple juice.
%error = [(experimental value-actual value)/actual value]*100.
Use the value from A as the actual value and the revised answer from B as the experimental value.

C.same procedure