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Extra Credit Unit 2 A possible points), CHEM 1120, Spring 2017 Hydrogen peroxide

ID: 522940 • Letter: E

Question

Extra Credit Unit 2 A possible points), CHEM 1120, Spring 2017 Hydrogen peroxide decomposes to water and oxygen according to the reaction below: 2 H202(aq) 2 H200) O20g The above reaction is performed in a 1.00 L container at 25oC and 1.00 atm pressure. oxygen gas generated during the reaction was collected over water. Use the obtained data, below, to answer the following questions: Time (S O2 (g) collected (mL) 0.00 4.00 mL 180 8.00 mL 270 16.00 mL 1. What is the average rate of disappearance of H2020aq) in M/s in the first 90.0 seconds of the reaction? Hint: you will need to determine the moles of o2 generated Rate AH202 H20 2 At 3A-r 2. What is the average rate of the reaction (in M/s) during the first 90.0 seconds? Suppose a titration with potassium permanganate (KMno4 was performed to monitor the rate of decomposition of hydroxgen peroxide. Use the obtained data, below, to answer the following questions: H202 M) Initial Rate (M/min 1.90 x 10 0.10 3.85 x 1 0.20 5.80 x 10 a 0.30 3. Write the rate law for this reaction:

Explanation / Answer

From the given data,

1. average rate of disappearence of H2O2 in first 90s

= 4/90 x 2

= 0.022 M/s

2. average rate of reaction in first 90s,

= 4/90

= 0.044 M/s

3. rate law for the given reaction,

when concentration of H2O2 is doubled, rate of reaction also doubled,

therefore,

rate = k[H2O2]

k is rate constant

4. rate constant k = 1.90 x 10^-4/0.1 = 1.90 x 10^-3 min-1

5. half-life of reaction

= ln(2)/k

= ln(2)/1.90 x 10^-3

= 364.814 min