option nolet
! serie : analytical chemistry
print "************************************************"
print "* calculation : relation between buffer index *"
print "* Beta(buffer monoprotic acid/salt: HA/MA)added*"
print "* strong acid (HCl) ? Ph A=Ac'(-)' ,M=Na'(+)'*"
print "* ( version 1.0 ) *"
print "************************************************"
print "------------------------------------------------"
print " [email protected],09/09/2016 "
print "------------------------------------------------"
print " Beta = dCb/dpH = - dCa/dpH 'buffer index' "
print "************************************************"
print " monoprotic acid: HA = H(+) + A(-) => ka "
print "************************************************"
! HA monoprotic weak acid ( example = HAc )
print "******************************************************"
print "* ka = ([H(+)][A(-)])/[HA] (1) *"
print "* Cb = moles NaOH = [Na(+)],Ca = moles HCl = [Cl(-)] *"
print "* C = [HA]+[A(-)] (2) *"
print "* (1) and (2) [A(-)] = C*ka/([H(+)]+ ka) (3) *"
print "******************************************************"
print " Charge Balance : *"
print "[H(+)]+[Na(+)] = [OH(-)]+[Cl(-)]+[A(-)] (4) *"
print " Cb=Ca+kw/[H(+)]-[H(+)]+C*ka/([H(+)]+ ka) (5) *"
print "******************************************************"
print " rem : pH = - log(10)[H(+)] = -1/ln(10) * ln[H(+)] *"
print " *****************************************************"
print " Beta = dCb/dpH = dCb/d[H(+)]*d[H(+)]/dpH "
print "***********************************************************"
print "*Beta = ln(10)*(kw/[H(+)]+[H(+)]+C*ka*[H(+)]/(ka+[H(+)])^2*"
print "***********************************************************"
print " del_pH = -del_Ca/Beta "
print "***********************************************************"
print " pH=pka + log([HA])/([A(-)]) + del_pH =pH_buffer + del_pH "
print "***********************************************************"
!file :Bufferindexweakacidversusstongacidfinalversion1.tru
print
print "*********"
print " given = "
print "*********"
ka =1.75E-5 ! ka from HAc equilibrium
print " ka from HA = ";ka
Ca = ad_HCL
ad_HCL = 0.001
print " added (strong acid) = ";ad_HCl;" mole"
print
print "***********"
print "*Buffer pH*"
print "***********"
MA = 0.010
print " NaAc 'Sodium acetate' = ";MA;" M"
HA = 0.010
print " HAc 'Acetic acid ' = ";HA;" M"
ratio = HA/MA
C = HA + MA ! see above NaAc -> Na(+) + Ac(-)
x=ka*ratio
print " [H(+)] concentration 'buffer' = ";x
pH_buffer = -(1/log(10))*log(x)
print " pH 'buffer' = ";pH_buffer
call beta_index(x,ka,C,Beta)
print
print " Beta (index) = ";Beta
print "************************************"
print "*pH = Buffer + added (strong Acid)*"
print "************************************"
del_pH = - ad_HCL/Beta
print " change in pH = ";del_pH
pH = pH_buffer + del_pH
print "******************************"
print " pH after added strong acid = ";pH
print "******************************"
end
sub beta_index(x,ka,C,Beta)
kw = 1E-14
q1 = C*ka*x
q2 =(ka+x)^2
q=q1/q2
Beta = log(10)*(kw/x+x+q)
end sub