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1. The second order decomposition of HI has a rate constant of 1.80 x 10-3 M-1s-

ID: 1017365 • Letter: 1

Question

1. The second order decomposition of HI has a rate constant of 1.80 x 10-3 M-1s-1. How much HI remains after 27.3 s if the initial concentration of HI is 4.78 M?

2. Write a nuclear equation to describe the neutron induced fission of U-235 to form Te-137 and Zr-97. Determine how many neutrons are produced in the reaction.

3. Consider the gas-phase decomposition of N2O5: N2O5(g) 2 NO2(g) + 1 half O2(g) This is known to be a first order reaction with a half-life of 102 s at 70°C. How long would it take for 35% of a sample of N2O5 to decompose at 70°C?

Explanation / Answer

1. The second order decomposition of HI has a rate constant of 1.80 x 10-3 M-1s-1. How much HI remains after 27.3 s if the initial concentration of HI is 4.78 M?

Answer =3.88 M

rate constant k =1.80 x 10^-3

t= 27.3 s

initial concentration of HI =4.78 M

plugging above values in the equation

1/[H] t =kt +1/[A]0

1/[A] t =(1.80 x 10^-3 (27.3)+1/4.78

1/[A] t =0.258

[A] t =1/0.258

            = 3.8759=3.88M answer


2. Write a nuclear equation to describe the neutron induced fission of U-235 to form Te-137 and Zr-97. Determine how many neutrons are produced in the reaction.

1n0 + 235U92 ->137 Te52 +97 Zr40 + 2 1n0    +gamma rays

Answer= 2

Element

mass

U

235

Te

137

zr

97

reactants

total

mass

1

235

236

products

total

mass

137

94

234

Element

mass

U

235

Te

137

zr

97