Kinetic practice eng

Page 1

Q1. Reaction: đ?&#x;?đ?‘¨ + đ?‘Š → đ?&#x;‘đ?‘Ş + đ?‘Ť Initial Rate Information: Concentration (M)

Experiment

[A] 0.24 0.12 0.24 0.0140

1 2 3 4

[B] 0.12 0.12 0.060 1.35

Rate (M/hr.) 2.00 0.50 1.00 X

Mechanism choice: 1.

đ??ľâ†’đ?‘Œ

đ?‘“đ?‘Žđ?‘ đ?‘Ą

2.

đ?‘Œ + đ??´ → đ??ˇ + đ?‘? đ?‘ đ?‘™đ?‘œđ?‘¤ đ?‘? + đ??´ → 3đ??ś

đ??´+đ??ľ →đ?‘Œ

đ?‘“đ?‘Žđ?‘ đ?‘Ą

đ?‘Œ + đ??´ → 3đ??ś + đ??ˇ

đ?‘ đ?‘™đ?‘œđ?‘¤

đ?‘“đ?‘Žđ?‘ đ?‘Ą

a) Write the rate law expression.

c) What is the final [C] for experiment 1.

b) Calculate k and x.

d) Select the best mechanism and explain.

Q2. The reaction between Habra and O2 is believed to occur in 3 steps: đ??ťđ??ľđ?‘&#x; + đ?‘‚2 → đ??ťđ?‘‚đ?‘‚đ??ľđ?‘&#x; đ??ťđ?‘‚đ?‘‚đ??ľđ?‘&#x; + đ??ťđ??ľđ?‘&#x; → 2đ??ťđ?‘‚đ??ľđ?‘&#x; đ??ťđ?‘‚đ??ľđ?‘&#x; + đ??ťđ??ľđ?‘&#x; → đ??ť2 đ?‘‚ + đ??ľđ?‘&#x;2 a) Write a balanced equation for the overall reaction b) Identify the intermediates. c) From the mechanism, Find out the rate-determining step when 1. Rate = k [Habra] [O2] 2. Rate = k [Habra] 2[O2] 3. Rate = k [Habra] 4[O2] d) Why does increasing temperature, rate constant will increase? Q3. The activation energy of a first order reaction is 50.2 kJ/moll at 25oC. What the temperature will the rate constant double? Q4. The relation between the natural log of concentration and time was shown in the graph. When we average these data, it shown the linear line which slightly decrease. These reaction had half-life 20 minute 1. Calculate the rate constant of the reaction. 2. Calculate the time which the reaction occur 75 %


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