Consider the reaction: 2H2O2( a q )2H2O( l )+O2( g ) The graph below (Figure 1)

Question

Consider the reaction:
2H2O2(aq)2H2O(l)+O2(g)
The graph below (Figure 1) shows the concentration of H2O2 as a function of time. Use the graph to calculate the following.

Part A: The average rate of the reaction between 10 and 20 s. Express your answer using two significant figures.

Part B: The instantaneous rate of the reaction at 30 s. Express your answer using one significant figure.

Part C: The instantaneous rate of formation of O2 at 50 s. Express your answer using one significant figure.

Part D: If the initial volume of the H2O2 is 2.0 L , what total amount of O2 (in moles) is formed in the first 50 s of reaction? Express your answer using one significant figure.

Explanation / Answer

Part A

Concentration at 10 s = 0.7 M

Concentration at 20 s = 0.5 M

therefore, average rate = - (0.5 -0.7) / 10 = 0.02 M/s

Part B

instantaneous rate at 30 s = 0.4 / 30 = 0.013M/s

Part C

instantaneous rate at 50 s = 0.21 / 50 = 4.2 X 10 ^(-3) M/s

Part D

from the chemical reaction it is clear that the amount of O2 formed = amt of H2O2 used / 2

Amt of O2 used in 50 s = 1- 0.21 = 0.79M

therefore amt of O2 formed = 0.395 M

no. of moles of O2 = 0.79 moles

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