Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and the Yahoo Answers website is now in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

Davy
Lv 4
Davy asked in Science & MathematicsChemistry · 1 decade ago

Given equation and a couple rates, how do you determine reaction order?

7. Given:

2A(g) + B(g) --> C(g) + D(g)

When [A] = [B] = 0.10 M, the rate is 2.0 M*s-1; for [A] = [B] = 0.20 M, the rate is 8.0 M*s-1; and for [A] = 0.10 M, [B] = 0.20 M, the rate is 2.0 M*s-1. The order of the reaction is :

I know that the answer will be 2, but I don't know how to get there. Help?

2 Answers

Relevance
  • HPV
    Lv 7
    1 decade ago
    Favorite Answer

    Construct a chart of [A], [B], and rate

    Trial No. . . . .[A] . . . .[B] . . . .rate (M/s)

    . .1 . . . . . .0.10 . . . .0.10 . . . .2.0

    . .2 . . . . . .0.20 . . . .0.20 . . . .8.0

    . .3 . . . . . .0.10 . . . .0.20 . . . .2.0

    To find the effect of changing [A] alone, look at Trials 3 and 2. [A] is double from 0.10 to 0.20 with [B] held constant. The rate changes by a factor of four. This is a 2nd-order relationship since 2^2 = 4. If we had tripled [A], the rate would have increased by a factor of 9 (3^2 = 9).

    Now to B. In Trials 1 and 3, we doubled [B] from 0.10 to 0.20 while holding [A] constant. Note that there is NO CHANGE in the rate at 2.0 M/s. This is a zer-order relationship, when we change the concentration of a reactant but the rate stays the same.

    The overall order of the reaction = order A + order B = 2 + 0 = 2.

  • ?
    Lv 4
    5 years ago

    How can the value regulation = ok[C]. besides the reality that i don't comprehend the respond, I disagree. The sluggish step (fee determining) is: X + C --> Y this means that the value regulation is = ok[X][C] however, considering that [X] isn't a reactant/product, it could't be secure interior the value regulation. yet whilst [X] is expressed in terms of [A] and [B], then this is secure interior the value regulation equation. i'm uncertain a thank you to precise [X] in [A] and [B]!!!! i think of you're attempting to assert that simply by fact the formation of [X] is so rapid this is disregarded because it is going to pile up (have an extremely super concentration) to attend to react with [C]. hence the plenty smaller concentration of [C] would be certain the value. That is clever to a pair quantity. however, what in case you talk the reaction between X and C independently. concentration of [X] could maximum in all risk be secure interior the value regulation equation. Now, placed this form, the concentration of [A] and [B] at the instant are not that vast to furnish this very super (countless) concentration of [X]. And concentration of [C] is fairly super. in accordance on your thought the value regulation could then be fee = ok[X] and not fee = ok[C]. the value regulation is neither ok[X] or ok[C]. It could desire to be fee = ok[C][X] to take up attention the two reactants. X could desire to then be expressed in [A]and[B]. My question is, how do you show [X] in terms of [A][B]?

Still have questions? Get your answers by asking now.