could you please check my work? thanks.

For the reaction between reactants A and B below, if 4.925 moles of A is placed into a flask with excess B it is found that the amount of A remaining after 6.85 seconds is 2.737 moles.

2A (g) + B (g)-----> 3 C (g)

a. find the rate of reaction with respect to A (in Ms^-1)
b. find the rate of the reaction with respect to B
c. find the reate of the reaction with respect to C


so far i have for part a:
rate = delta [A]/delta t
i calculated the molarities of before and after:
4.925mols/3.00L = 1.64 M
2.727mols/3.00L = .912 M

delta M = .728
but that's supposed to be negative because the number of mols decreases correct?
so i got -.728 M

delta t = 6.85 (0 to 6.85 seconds)

so rate a = -(.728M/6.85 seconds)
but since reactants are involved it should be negative on the outside too, so it's
=-(-.728M/6.85 s)
=.106 Ms^-1

is that correct????
to find b woul i just divide the mols of A by two????

To check your work for part a, let's go through the calculations:

You correctly calculated the initial and final molarities of A as follows:

Initial molarity of A = 4.925 moles / 3.00 L = 1.64 M
Final molarity of A = 2.737 moles / 3.00 L = 0.912 M

The change in molarity (delta [A]) is the difference between the final and initial molarities:

delta [A] = 0.912 M - 1.64 M = -0.728 M

Since the number of moles of A decreases, the change in molarity is indeed negative.

Now, let's calculate the rate of reaction with respect to A:

Rate of reaction = delta [A] / delta t
delta t = 6.85 seconds (from 0 to 6.85 seconds)

Rate of reaction (with respect to A) = -0.728 M / 6.85 s
Since reactants are involved, the rate should be negative, so we have:

Rate of reaction (with respect to A) = -(-0.728 M / 6.85 s) = 0.106 Ms^-1

So, your calculation for part a is correct.

For part b, to find the rate of the reaction with respect to B, you cannot simply divide the moles of A by two. The balanced equation indicates that the stoichiometry between A and B is 2:1. Here's how you can calculate the rate of reaction with respect to B:

Rate of reaction (with respect to B) = (-1 / 2) * (delta [A] / delta t)
Since reactants are involved, the rate should be negative:

Rate of reaction (with respect to B) = -(-1 / 2) * (-0.728 M / 6.85 s)

Simplifying this expression will give you the correct rate of reaction with respect to B.

For part c, to find the rate of the reaction with respect to C, you will have to use the stoichiometry of the reaction. Since the stoichiometric coefficient of C is 3, you will need to multiply the rate of reaction with respect to A by 3.

I hope this helps you check your work! If you have any further questions, feel free to ask.