1. Radioactive materials are often used in biological studies. A radiation biologist studies the rate of decomposition of a certain substance and obtains the following data:

Time (days) 0 4.0 8.0 12.0 16.0 Mass (μg)28.40 19.89 13.93 9.76 6.84

Determine the rate constant in units of days-1.

How many micrograms will remain after 29 days?

2.Given the following data for a chemical reaction, determine whether it is a zero, first, or second order reaction, and then calculate the concentration at time = 50 seconds. (Enter in units of M).

Time(s)0 10.0 20.0 30.0 Concentration (M)0.94 0.82 0.70 0.58

3.The rate at which a certain Australian tree cricket chirps is 186/min at 33°C, but only 33.4/min at 9°C, From these data calculate the energy of activation for the chirping process. (Hint: the ratio of the rates is equal to the ratio of the rate constants.) Enter in units of kJ/mol.