a concentration-time study of the gas phase reaction a 2A3 -> 3A2 produced the data in the table below.
Time (s) [A3] (M) [A2] (M)
0 4.00 × 10–4 0
10 2.00 × 10–4 3.00 × 10–4
20 1.00 × 10–4 4.50 × 10–4
30 5.00 × 10–5
A) What is the concentration of A2 in the time interval 20-30 seconds?
I got 7.50 x 10^-6
B) What is the concentration of A2 after 30 seconds?
I got 5.00 x 10^-5
To find the concentration of A2 in the time interval 20-30 seconds, you need to calculate the change in concentration of A2 during that time period.
First, subtract the concentration of A2 at 20 seconds from the concentration of A2 at 30 seconds:
[A2] at 30 seconds - [A2] at 20 seconds
= 5.00 × 10^(-5) M - 4.50 × 10^(-4) M
= -3.50 × 10^(-4) M
Note that the concentration of A2 at 30 seconds is missing in the given data, so it cannot be calculated precisely.
Based on the given data, after 30 seconds, the concentration of A2 becomes zero.
To find the concentration of A2 after 30 seconds, you can use the concentration-time data given. From the table, we can see that at 30 seconds the concentration of A2 is not provided.
However, we can use the information given to estimate the concentration of A2 after 30 seconds. We can assume that the rate of change in concentration between 20-30 seconds is the same as the rate of change between 10-20 seconds.
To calculate the rate of change, we can use the formula:
Rate = (change in concentration) / (change in time)
From 10-20 seconds, the concentration of A2 changes from 3.00 × 10–4 M to 4.50 × 10–4 M in 10 seconds.
Change in concentration = (4.50 × 10–4 M) - (3.00 × 10–4 M) = 1.50 × 10–4 M
Change in time = 20 seconds - 10 seconds = 10 seconds
Rate = (1.50 × 10–4 M) / (10 seconds) = 1.50 × 10–5 M/s
Now, we can assume that the rate of change is constant between 20-30 seconds. We can calculate the concentration change by multiplying the rate by the time interval:
Change in concentration = (1.50 × 10–5 M/s) * (10 seconds) = 1.50 × 10–4 M
To find the concentration after 30 seconds, we add this change to the concentration at 20 seconds:
Concentration at 30 seconds = (4.50 × 10–4 M) + (1.50 × 10–4 M) = 6.00 × 10–4 M
Therefore, the concentration of A2 after 30 seconds is 6.00 × 10–4 M.