In: Chemistry
A 25.0 mL sample of a 0.150 M weak acid, Ka = 4.6 x 10−5 , is titrated with 0.200 M NaOH. Calculate the pH when 10.0 mL of the base has been titrated into the acid.
no of moles of acid HA = molarity * volume in L
= 0.15*0.025 = 0.00375 moles
no of moles of NaOH = molarity * volume in L
= 0.2*0.01 = 0.002mole
HA + NaOH ----------------> NaA + 2H2O
I 0.00375 0.002 0
C -0.002 -0.002 0.002
E 0.00175 0 0.002
Ka = 4.6*10^-5
PKa = -logKa
= -log4.6*10^-5
= 4.3372
PH = Pka + log[NaA]/[HA]
= 4.3372 + log0.002/0.00175
= 4.3372 + 0.05799
= 4.3951 >>>>>answer