Question

Consider the reaction
2H3PO4>P2O5+3H2O
Using the information in the following table, calculate the average rate of formation of P2O5 between 10.0 and 40.0 s
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Time(s)| 0 | 10.0 | 20.0 | 30.0 | 40.0 | 50.0 |
P2O5 (M)| 0 | 1.70×10^-3 | 4.70×10^-3 | 6.50×10^-3 | 7.70×10-3 | 8.30×10^-3 |

Part B
Determine the average rate of decomposition of H3PO4 between 10.0 and 40.0 s

Part C
Consider the reaction
5Br^- (aq)+ BrO3- (aq)+ 6H^+(aq)+3H2O(l)

The average rate of consumption of Br- is 1.16×10^-4 M/s over the first two minutes. What is the average rate of formation of Br2 during the same time interval?

Answer 1

Average rate is the change in concentration divided by time interval

Part A:

at time (t1) = 10 sec, the concentration (C1) =  1.70x10^-3 M

at time (t2) = 40 sec, the concentration (C1) =  7.70x10^-3 M

Rate of reaction = (C2 - C1) / (t2 - t1) = (7.70 x 10^-3 M - 1.70 x 10^-3 M) / (40s - 10s)

Rate of reaction = 2.0 x 10^-4 M/s

Part B

Rate of disappearance of H3PO4 = Rate of appearance of P2O5

Part C

Rate of consumption of Br- = Rate of fromation of Br2