Question

Citric acid is often used as an acidity regulator in hot water canning of tomatoes. At 25°C it has Kat 7.4x10- and A.Hº = +4.1 kl/mol for the acid dissociation process. What is the value of the Kat of citric acid at 100°C? к ТС о

Answer 1

The rate constant at T = 100 C is 1.0*10⁻³

Step-by-step explanation:

The Arrhenius equation relates two rate constants K1 and K2 measured at temperatures T1 and T2 as shown below:

`ln(K_(2))/(K_(1))=(\Delta H^(0)rxn)/(R)((1)/(T_(1))-(1)/(T_(2)))`

here, ΔHrxn = standard enthalpy change of the reaction

R = gas constant

From the given information:

K1 = 7.4*10^-4

T1 = 25 C = 25+273 = 298 K

T2 = 100 C = 100+273 = 373K

ΔH°=4.1kJ/mol

`ln(K_(2))/(7.4*10^(-4))=(4.1 kJ/mol)/(0.08314kJ/mol.K)((1)/(298)-(1)/(373))K`

K2 = 1.03*10⁻³