Answer:
(a) -0.00017 M/s;
(b) 0.00034 M/s
Explanation:
(a) Rate of a reaction is defined as change in molarity in a unit time, that is:
Given the following reaction:
We may write the rate expression in terms of reactants firstly. Since reactants are decreasing in molarity, we're adding a negative sign. Similarly, if we wish to look at the overall reaction rate, we need to divide by stoichiometric coefficients:
Reaction rate is also equal to the rate of formation of products divided by their coefficients:
Let's find the rate of disappearance of the reactant firstly. This would be found dividing the change in molarity by the change in time:
(b) Using the relationship derived previously, we know that:
Rate of appearance of nitrogen dioxide is given by:
Which is obtained from the equation:
If we multiply both sides by 4, that is:
This yields:
[tex]r_{NO_2} = \frac{\Delta [NO_2]}{\Delta t} = -2\frac{\Delta [N_2O_5]}{ \Delta t} = -2\cdot (-0.00017 M/s) = 0.00034 M/s[tex]
