If the concentration of cucl2 drops from 1.000 m to 0.655 m in the first 30.0 s of the reaction, what is the average rate of reaction over this time interval?

Answer: 0.0115 M/s

Justification:

1) Assuming constatn volume, the rate or velocity of reaction is:

rate = change in concentration / time

2) The change is concentration is 0.100 M - 0.655 M = 0.345 M

3) The time was 30 s

4) Therefore the rate is: 0.345 / 30s = 0.0115 M/s