Question

The rate of the reaction in terms of the "disappearance of reactant" includes the change in the concentration of the reactant, the time interval, and the coefficient of the reactant.

Consider the following reaction:

2A+3B→3C+2D

The concentrations of reactant A at three different time intervals are given. Use the following data to determine the average rate of reaction in terms of the disappearance of reactant A between time = 0 s and time = 20 s .

Time (s ) 0 20 40
[A](M) 0.0400 0.0240 0.0180
Express your answer in molar concentration per second to three significant figures.

Part B

The rate of the reaction in terms of the "appearance of product" includes the change in the concentration of the product, the time interval, and the coefficient of the product.

Consider the following reaction:

2A+3B→3C+2D

The concentrations of product C at three different time intervals are given. Use the following data to determine the rate of reaction in terms of the appearance of product C between time = 0 s and time = 20 s .

Time (s ) 0 20 40
[C](M) 0.000 0.0240 0.0480
Express your answer in molar concentration per second to three significant figures.

Answer 1

The average rate of reaction based on the disappearance of A from 0 to 20 seconds is 0.00080 M/s, while the rate of appearance of C is 0.00180 M/s when accounting for stoichiometry.

Step-by-step explanation:

The average rate of reaction in terms of the disappearance of reactant A between time = 0 s and time = 20 s can be calculated using the given concentrations. The rate of reaction is calculated with the change in concentration of A over time, which is the final concentration minus the initial concentration, divided by the time interval.

The initial concentration of A at time = 0 s is 0.0400 M, and the final concentration of A at time = 20 s is 0.0240 M. The change in concentration (Δ[A]) is 0.0400 M - 0.0240 M = 0.0160 M. The time interval (Δt) is 20 s - 0 s = 20 s. Therefore, the average rate of disappearance of A is 0.0160 M / 20 s = 0.00080 M/s.

For part B, the rate of reaction in terms of the appearance of product C between time = 0 s and time = 20 s can be calculated similarly. The initial concentration of C is 0.000 M and the final concentration is 0.0240 M. The change in concentration of C (Δ[C]) is 0.0240 M - 0.000 M = 0.0240 M over 20 s. However, the stoichiometry of the reaction must be considered, for every 2 moles of A disappearing, 3 moles of C appear. The rate of appearance of C is then (0.0240 M / 20 s) * (3/2) = 0.00180 M/s.