CALCULATION :

CASE 1: TO FIND THE ENHANCEMENT FACTOR WHEN BENZOIC ACID IS DISSOLVED IN 1.5 L of 0.5N NaOH FOR A DURATION OF 10 MINUTES .

BEFORE EXPERIMENT

Outer diameter of the benzoic acid cylinder = 3.4 cm

Length of the benzoic acid cylinder = 4.9 cm

AFTER EXPERIMENT

Outer diameter of the benzoic acid cylinder = 2.75 cm

Length of the benzoic acid cylinder = 4.01 cm

Normality of HCL used for titration (N₁) = 0.5 N

Volume of 0.5 N HCL used (V₁) = 9.4 ml

Volume of NaOH taken (V₂) = 10 ml

Let the normality of unused NaOH in dissolution be N₂

N₁V₁ = N₂V₂

N₂ =N₁V₁ /V₂

=0.47 N

The concentration of unused NaOH = 0.47 N

The rate of dissolution of benzoic acid = R

R = N₂*Volume of NaOH soln in tank

=1.175 *10^(-6) kmol/sec

Let the average dimensions of benzoic acid cylinder be

D_av = (3.4 + 2.75 )/2

= 3.075 cm

L_av = (4.9 + 4.01)/2

= 4.455 cm

Let S.S rod diameter d = 0.78 cm

Average surface area (AS)

= 56.9*10(^-4) m²

Specific rate of dissolution R'

= 2.1* 10(^-4) kmol/m² - sec