Chapter 14, Problem 101a
This reaction has an activation energy of zero in the gas phase: CH3 + CH3 → C2H6 a. Would you expect the rate of this reaction to change very much with temperature?
Video transcript
The kinetics of this reaction were studied as a function of temperature. (The reaction is first order in each reactant and second order overall.)
C2H5Br(aq) + OH- (aq) → C2H5OH(l) + Br- (aq)
Temperature (°C) k (L,mol •s)
25 8.81⨉10-5
35 0.000285
45 0.000854
55 0.00239
65 0.00633
c. If a reaction mixture is 0.155 M in C2H5Brand 0.250 M in OH-, what is the initial rate of the reaction at 75 °C?
The reaction 2 N2O5 → 2 N2O4 + O2 takes place at around room temperature in solvents such as CCl4. The rate constant at 293 K is found to be 2.35⨉10-4 s-1, and at 303 K the rate constant is found to be 9.15⨉10-4 s-1. Calculate the frequency factor for the reaction.
Consider the two reactions:
O + N2 → NO + N Ea = 315 kJ/mol
Cl + H2 → HCl + H Ea = 23 kJ/mol
a. Why is the activation barrier for the first reaction so much higher than that for the second?
Consider the two reactions:
O + N2 → NO + N Ea = 315 kJ/mol
Cl + H2 → HCl + H Ea = 23 kJ/mol
b. The frequency factors for these two reactions are very close to each other in value. Assuming that they are the same, calculate the ratio of the reaction rate constants for these two reactions at 25 °C.
Anthropologists can estimate the age of a bone or other sample of organic matter by its carbon-14 content. The carbon-14 in a living organism is constant until the organism dies, after which carbon- 14 decays with first-order kinetics and a half-life of 5730 years. Suppose a bone from an ancient human contains 19.5% of the C-14 found in living organisms. How old is the bone?