1) if the concentrations of trace constituients of the atmosphere are expressed in molecules/cm3 , what would be the units of reaction rate????
i think the ans is molecules/cm3 per seconds since the usual units of reaction rate is mol per dm3 per seconds.....am i correct?
Yes, you are correct. When the concentrations of trace constituents in the atmosphere are expressed in molecules/cm3, the units of reaction rate would be molecules/cm3 per second.
The usual units of reaction rate are commonly expressed in terms of moles per liter per second (mol/L/s) or, more commonly, mol/dm3/s. Since 1 cm3 is equal to 1/1000 of a liter (or 1/1000 of a dm3), the units for reaction rate in terms of molecules/cm3 per second can be obtained by simply converting the units from mol/dm3/s to molecules/cm3 per second.
It is important to note that the reaction rate is a measure of how fast a reaction occurs with respect to the change in concentration over time. So, when expressing the concentration in molecules/cm3, the reaction rate will be in molecules/cm3 per second.
Therefore, your answer of molecules/cm3 per second is correct.