The thermal degradation of silk was studied by Kuruppillai, Hersh, and Tucker ("Historic Textile and Paper Materials," ACS Advances in Chemistry Series, No. 212, 1986 by measuring the tensile strength of silk fibers at various times of exposure to elevated temperature. The loss of tensile strength follows first-order kinetics, −dsdt=ks where s is the strength of the fiber retained after heating and k is the first-order rate constant. The effects of adding a deacidifying agent and an antioxidant to the silk were studied, and the following data were obtained: Strength Retained (%) HeatingTimeDeacidifying(days)UntreatedAgentAntioxidant0.00100.0100.1114.61.0067.960.865.22.0038.926.828.13.0016.1−−11.36.006.8−−−−−− a. Determine the first-order rate constants for the thermal degradation of silk for each of the three experiments. b. Does either of the two additives appear to retard the degradation of silk? c. Calculate the half-life for the thermal degradation of silk for each of the three experiments.

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The thermal degradation of silk was studied by Kuruppillai, Hersh, and Tucker (&quot;Historic Textile and Paper Materials,&quot; ACS Advances in Chemistry Series, No. 212, 1986 by measuring the tensile strength of silk fibers at various times of exposure to elevated temperature. The loss of tensile strength follows first-order kinetics, −dsdt=ks where s is the strength of the fiber retained after heating and k is the first-order rate constant. The effects of adding a deacidifying agent and an antioxidant to the silk were studied, and the following data were obtained: Strength Retained (%) HeatingTimeDeacidifying(days)UntreatedAgentAntioxidant0.00100.0100.1114.61.0067.960.865.22.0038.926.828.13.0016.1−−11.36.006.8−−−−−− a. Determine the first-order rate constants for the thermal degradation of silk for each of the three experiments. b. Does either of the two additives appear to retard the degradation of silk? c. Calculate the half-life for the thermal degradation of silk for each of the three experiments.

hajavaF · Accepted Answer

a) untreated k=0.465day−1    deacidifying k=0.659day−1    antioxidant k=0.779day−1    b) Both additives are increasing the rate of degradation process.    c) untreated t12=ln⁡20.465days−1=1.49 days.    deacidifying t12=ln⁡20.659days−1=1.05 days.    antioxidant t12=ln⁡20.779days−1=0.890 days.

a. Determine the first-order rate constants for the thermal degradation of silk for each of the three experiments.

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