The decomposition of formic acid follows first-order kinetics. HCO_2 H(g) righta
ID: 539260 • Letter: T
Question
The decomposition of formic acid follows first-order kinetics. HCO_2 H(g) rightarrow CO_2 (g) + H_2 (g) The half-life for the reaction at 550 degree C is 24 seconds. How many seconds does it take for the formic acid concentration to decrease by 75%? a. 6.0 s b. 18 s c. 24 s d. 36 s e. 48 s What is the half-life of a first-order reaction if it takes 4.8 times 10^-3 seconds for the concentration to decrease from 1.33 M to 0.51 M? a. 1.8 times 10^-3 s b. 3.5 times 10^-3 s c. l.3 times 10^-2 s d. 2.0 times 10^2 s e. 3.8 times 10^2 s For the second-order reaction below, the initial concentration of reactant A is 0.24 M. If the rate constant for the reaction is 5.5 times 10^-3 M^-1 s^-1, what is the concentration of A after 265 seconds? 2A rightarrow B + C rate = k[A]^2 a. 0.056 M b. 0.035 M c. 0.18 M d. 0 21 M e. 0.37 M According to collision theory, which condition(s) must be met in order for molecules to react? 1. The reacting molecules must collide with each other to react. 2. A catalyst must be in contact with the reacting molecules for a reaction to occur. 3. The reacting molecules must collide with an orientation that can lead to rearrangement of the atoms. a. 1 only b. 2 only c. 3 only d. 1 and 2 e. 1 and 3 In general, as temperature increases, the rate of a chemical reaction a. decreases due to fewer collisions with proper molecular orientation. b. decreases for endothermic reactions. c. decreases due to an increase in the activation energy. d. increases due to a decrease in the activation energy. e. increases due to a greater number of effective collisions.Explanation / Answer
16.
one half life= 50 % conc
two half life = 75 % conc
time = 2*24 = 48 sec(e)
17.
first order kinetic eqn =
Ln(inital conc/final conc)= kt
Ln(1.33/.51)= k* 4.8*10-3
k= 199.6
half life for order 1= ln(2)/k
= 3.5*10-3 sec(b)
18.
(1/A) - (1/Ao) =kt
1/A-4.167 = 1.457
A =.18 M (c) = final concentration
19.
According to collision theory molecules must collide with orientation that can lead to product formation
so answer will be part d as it also include collision part
20.
At higher temp thermal energy of molecules increaqse s they move at higher speeds. Due to increased movements the no of collsions become higher and hence rate of reaction increases. so answer wiil be part d
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