Week 9 and 10 Sapling #1

[Amanda Bueno-Kling]

I am trying to work through this sapling problem and a bit stuck as I am not sure what equation to use.
The problem I am given is:
The rate of the given reaction is 0.600 M/s.
A + 4B ---> 2C
I figured out that delta [A]/delta t is -0.600 M/s, since every second all of the A breaks down. But I am not sure what formulas to use for C and B and how to set them up? Can anyone explain to me the general rule or formula for these two?

[Amanda Bueno-Kling]

I figured this one out after a bit! It is rate = 0.600 = -/+ (1/coeficient)(delta[X]/delta t), with - signs for products since they decrease, and + signs for reactants since they increase.
So for B, it is 0.600= -1/4(delta[B]/delta t), and for C it is 0.600= 1/2(delta[C]/delta t).

[Katie Shi 1F]

I just approached this by looking at the stoichiometric relationships between each species. If the rate of reaction is .600 M/s, we know A is decreasing at .600 M/s (negative value). We know B will be decreasing at a rate of 4 times that (negative value), and that C will be increasing at a rate 2 times that (positive value).

[Jordan Kaplan 2E]

What helps me remember this is to imagine the rate how we imagine molar ratios. If the overall rate is 0.600 M/s it is for "1 mol" of reactant. The only species in this example with a coefficient of 1 is A, so the rate of A= -0.600 (- because it is a reactant). B has a coefficient of 2, so it will be twice the "amount" of the rate: -1.2M/s. C is 4x the amount, so it is +2.4 M/s (+ because it is a product and getting formed). Hope this helps!