87.4 Activity and activity coefficient Out-class extensive reading ra n. Levine, pp 294-300 Section 10.6 solutions of electrolytes Section 10. 7 determination of electrolyte activity coefficients
§7.4 Activity and activity coefficient Out-class extensive reading: Ira N. Levine, pp. 294-300 Section 10.6 solutions of electrolytes Section 10.7 determination of electrolyte activity coefficients
87.4 Activity and activity coefficient Some facts of strong electrolytes solution present species 0.52 mol- 3KCI 95%K++5%KCl 0. 25 mol,SO4 76% Na*+ 24%NaSO4 0.1 mol dm-3 CuSo 44% CuSO Effective concentration is rather different from the actual concentration Activity coefficient is essential for quite dilute solutions
solution present species 0.52 mol·dm-3 KCl 95% K+ + 5% KCl 0.25 mol·dm-3 Na2SO4 76 % Na+ + 24% NaSO4 ¯ 0.1 mol·dm-3 CuSO4 44% CuSO4 Some facts of strong electrolytes Effective concentration is rather different from the actual concentration Activity coefficient is essential for quite dilute solutions §7.4 Activity and activity coefficient
87.4 Activity and activity coefficient 1. Concepts For ideal or dilute non-electrolyte solution AB=uR(T)+RTIn m For nonideal solution of non-electrolytes uB=UR(T)+RtIn a Bm aB,m rBh e For electrolytic solution such as dilute Hcl solution HCI(aHci=h(au+)+cl(a) y+ a=y-6
For ideal or dilute non-electrolyte solution B B B ( ) ln m T RT m = + For nonideal solution of non-electrolytes B B B,m = + ( ) ln T RT a B B,m B,m m a m = 1. Concepts For electrolytic solution such as dilute HCl solution: HCl H Cl HCl( ) H ( ) Cl ( ) a a a + − + − = + m a m + + + = m a m − − − = §7.4 Activity and activity coefficient
87.4 Activity and activity coefficient 1. Concepts H=uH(T)+RTinayt Hcr=f- (t)+rTinaci HCI HCI CI=FHCI+RT in(qH.ac) WHCI=AHCI (T)+rT In aHcI Therefore: a Because solution only containing single ion does not exist, the activity of individual ion is unmeasurable, therefore, we use mean activity instead mean activity a=a,a=at a,Va=(a,a)
HCl HCl HCl = + ( ) ln T RT a Therefore: HCl H Cl a a a = + − Because solution only containing single ion does not exist, the activity of individual ion is unmeasurable, therefore, we use mean activity instead. mean activity 2 + − = a = a a a 2 1 ( ) a = a = a+ a− H H H + + + = + ( ) ln T RT a Cl Cl Cl − − − = + ( ) ln T RT a HCl H Cl = ++ − HCl H Cl = ++ − HCl HCl H Cl = + RT a a ln( ) + − 1. Concepts §7.4 Activity and activity coefficient
87.4 Activity and activity coefficient 1. Concepts For a salt with general formula Mu x M X vM+yX 1=V+H4+v 4=+ rTIn a4=12+ RTIn ym=4°+RTna=°+ RTIn y-m u=(vux+vu+RTInyr'+rtInm m Definition: b+=y+ m*=mm-Iv=v++v u=(vur+v_u)+vRTIn++vRTInm Molality-scale mean ionic activity coefficient C. Levine pp 295-297
For a salt with general formula Mv+Xv- = + + + − − v v RT a RT m ln ln + + + + + + = + = + RT a RT m ln ln − − − − − − = + = + ( ) ln ln v v v v v v RT RT m m + − + − = + + + + + − − + − + − Definition: + − = + − v v v + − = + − v v v m m m = + + − v v v = + + + ( ) ln ln v v vRT vRT m + + − − Cf. Levine pp. 295-297 Molality-scale mean ionic activity coefficient 1. Concepts §7.4 Activity and activity coefficient