Practice Problem 8
Hydrogen iodide decomposes to give a mixture of hydrogen and iodine:
2 HI(g) H2(g) + I2(g)
Use the following data to determine whether the decomposition of HI in the gas phase is first order or second order in hydrogen iodide.
Initial (HI) (M) Initial Instantaneous
Rate of Reaction (M/s)
Trial 1: 1.0 x 10-2 4.0 x 10-6
Trial 2: 2.0 x 10-2 1.6 x 10-5
Trial 3: 3.0 x 10-2 3.6 x 10-5
Answer
The reaction is second order in HI:
Rate = k(HI)2