[imarockstar858]

1 point(s))   
  The compound AX2 decomposes according to the equation, 2 AX2(g) => 2 AX(g) + X2(g). In one experiment, [AX2] was measured at various times, and these data recorded:
Time (s)    [AX2] mol/L
0            0.0500
2.0          0.0448
6.0          0.0300
8.0          0.0249
10.0        0.0209
20.0        0.0088

What is the average rate from 6.0 to 20.0 seconds in mol / L s? [don't include units in your answer; if you want to use scientific notation, use the E format. e.g., 0.0011 is 1.1E-3
 
I just averaged the numbers given, but i didn't get NEAR the answer that was correct. Is there a particular formula I need to be using?

This is what I did:
What I origionally did was  add the results from 6 sec to 20 sec:
.03 + .0249 + .0209 + .0088= .0846
 then I divided it by the T final by T initial, 20-6 = 14 sec
so .0846 / 14 = 6.04E-3

but the real and correct answer is: 1.5E-3

How was I so far off?
Thanks

[macman104]

Show your calculations please.

[imarockstar858]

What I origionally did was  add the results from 6 sec to 20 sec:
.03 + .0249 + .0209 + .0088= .0846
 then I divided it by the T final by T initial, 20-6 = 14 sec
so .0846 / 14 = 6.04E-3

but the real and correct answer is: 1.5E-3

How was I so far off?

[macman104]

You are not taking the average of the values, you need to find the slope.  You know the equation:

[imarockstar858]

Yes.. but how does that apply?
What would be your X and Y?  Would X be time?

So... Assuming X is time...

0.0088  -  0.0300  / 20-6


OH!! and thats the right answer.
Thank you so much!