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

Answer:

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

Explanation:

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

$ln\frac{K_{2}}{K_{1}}=\frac{\Delta H^{0}rxn}{R}(\frac{1}{T_{1}}-\frac{1}{T_{2}})$

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

$ln\frac{K_{2}}{7.4*10^{-4}}=\frac{4.1 kJ/mol}{0.08314kJ/mol.K}(\frac{1}{298}-\frac{1}{373})K$

K2 = 1.03*10⁻³