1. A 25.0 mL aliquot of vinegar was diluted to 250 mL in a volumetric flask. Titration of 50.0 mL aliquots of the diluted solution required an average of 34.8M NaOH. Express the acidity of the vinegar as a weight/volume % of CH3COOH.

2. What masses of solid Tris [ (HOCH2)3CNH2 ] and Tris HCl [ (HOCH2)3CN+H3.Cl- ], pKa=8.07, should be combined and diluted to 100.0 mL to make a 0.100 M buffer with pH= 7.40 ?

use M1V1 = moles of NaOH
to take out molarity of diluted solution
now get the molarity of stock solution again using the same equation
M1V1=M2V2
now get the moles in 25mL of the stock solution
convert it in mass
take ratio of mass X100%/volume to take out w%/V