For the elementary reaction 2A + B= 3C,if the rate of appearance of C at time ' t ' is 1.3*10^{-4} mol L^{-1} s^{-1} ,calculate at this time (1) rate of reaction (2) rate of disappearance of A.

We know that for any reaction of the form:

aA + bB -> cC + dD,

the rate of a reaction is given by the formula: r = (-1/a)(rate of disappearance of A) = (-1/b)(rate of disappearance of B) = (1/c)(rate of appearance of C) = (1/d)(rate of appearance of D)

Given reaction : 2A + B -> 3C

Rate of appearance of C = 1.3*10^{-4} mol L^{-1} s^{-1}

Here, c = 3

(1) Therefore, Rate of reaction = (1/3)(1.3*10^{-4} mol L^{-1} s^{-1}) = 0.433 *10^{-4} mol L^{-1} s^{-1}

(2) Also we know that rate of reaction = (-1/a)(Rate of disappearance of A)

Here, a = 2

0.433 * 10^{-4} = (-1/2) (Rate of disappearance of A)

Hence, Rate of disappearance of A = 2 * 0.433 * 10^{-4} = -0.867 10^{-4} mol L^{-1} s^{-1}

-ve sign indicates A decreases over time.

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