Reaction rate order problem

[keikoblue2]

This is a question from a Kaplan FL.

Ok I'm not sure why the image isn't working. Here's the link: http://imageshack.us/f/11/dqng.png/
From their explanation, it seems like

4 * (doubling A) = 16x increase in rate
So doubling A = 4x increase in rate
So A is second order.

Following this logic, I tried solving for the order of B this way and ran into a problem.
2 * (quadrupling B) = 16x increase in rate
So quadrupling B = 8x increase in rate
??? B doesn't come out to be first order?

I know how to solve the the rate orders if only one rate is changing, and the other rates remain the same (like how the answer solved for the rate order of B) but I'm not sure what they did to solve for A.

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[Gauss44]

This is a question from a Kaplan FL.

Ok I'm not sure why the image isn't working. Here's the link: http://imageshack.us/f/11/dqng.png/
From their explanation, it seems like

4 * (doubling A) = 16x increase in rate
So doubling A = 4x increase in rate
So A is second order.

Following this logic, I tried solving for the order of B this way and ran into a problem.
2 * (quadrupling B) = 16x increase in rate
So quadrupling B = 8x increase in rate
??? B doesn't come out to be first order?

I know how to solve the the rate orders if only one rate is changing, and the other rates remain the same (like how the answer solved for the rate order of B) but I'm not sure what they did to solve for A.

Since, the concentration of B quadrupled in trials 1 & 2 (the top two rows), the rate would quadrupled due to B in addition to whatever influence A has. Since the rate actually increased by a factor of 16, it also quadrupled due to A.

Since B is first order, the rate changes by the same factor as the concentration due to B.
Since A is second order, the rate changes by a larger factor than the concentration due to A.

 

[keikoblue2]

Since, the concentration of B quadrupled in trials 1 & 2 (the top two rows), the rate would quadrupled due to B in addition to whatever influence A has. Since the rate actually increased by a factor of 16, it also quadrupled due to A.

Since B is first order, the rate changes by the same factor as the concentration due to B.
Since A is second order, the rate changes by a larger factor than the concentration due to A.

Oh I see, thank you! So my mistake when I wrote 2 x (quadrupled B) was that I made A first order by accident. It seems like one of the orders would be given/easy to figure out, and then using that information, I can figure out the second rate through this method.

Thanks again!