Answer:
[tex]4.00\cdot 10^{-5} \frac{mol}{dm^3 s}[/tex]
Explanation:
The rate of a chemical reaction is defined as the rate of change of molarity with respect to time. That is, finding the change in molarity and dividing by the change in time will yield the average rate of a reaction.
In this problem, we firstly need to identify the initial molarity, the final molarity, find their difference and divide by the time passed.
Firstly, find the initial molarity dividing the number of moles by the given volume:
[tex]c_1 = \frac{0.300 mol}{1.00 dm^3} = 0.300 mol/dm^3[/tex]
Secondly, define the equation based on our definition to calculate the reaction rate:
[tex]r = \frac{\Delta c}{\Delta t} = \frac{c_2 - c_1}{\Delta t}[/tex]
Given the final molarity of:
[tex]c_2 = 0.296 mol/dm^3[/tex]
We obtain the average rate of change as:
[tex]r = \frac{0.296 mol/dm^3 - 0.300 mol/dm^3}{100 s} = -4.00\cdot 10^{-5} \frac{mol}{dm^3 s}[/tex]
This is, however, the rate of disappearance of ethanol. The reaction rate with respect to the reactants is just the negative value of the rate of change of the reactants:
[tex]r = -r_{reactants} = -(-4.00\cdot 10^{-5} \frac{mol}{dm^3 s}) = 4.00\cdot 10^{-5} \frac{mol}{dm^3 s}[/tex]
