I. Concentration II. Temperature of reactants III. Surface area of reactants Please mark 1 answer: A. I and III only B. I and II only C. I, II and III D. II and III only 3A (aq) -> 2B (aq) + C (aq), the decomposition of compound A at 300 K in a solution with constant volume can be followed by monitoring the concentration of A. Initially, the concentration of A is 2.94 mol dm⁻³, and after 1.3 min, it is reduced to 1.76 mol dm⁻³. Calculate the rate of the reaction. Please mark 1 answer: A. 5 x 10³ mol dm⁻³ s⁻¹ B. 0.0504 mol dm⁻³ s⁻¹ C. 3 x 10² mol dm⁻³ s⁻¹ D. 3.8 x 10³ mol dm⁻³ s⁻¹
Answer (1)
When determining factors that affect the rate of a chemical reaction, we generally consider several aspects:
I. Concentration - Increasing the concentration of reactants typically increases the reaction rate because there are more reactant molecules that can collide with each other.
II. Temperature of Reactants - Raising the temperature usually increases the rate of a chemical reaction because it increases the energy of the molecules, leading to more frequent and energetic collisions.
III. Surface Area of Reactants - Increasing the surface area allows more reactant particles to be exposed and available for reaction, which increases the rate of reaction.
For the first part of the question, all three factors, (I, II, and III), influence reaction rates. Therefore, the correct multiple-choice answer is C. I, II, and III .
Next, we'll calculate the rate of the reaction for the decomposition of compound A:
Given the decomposition reaction:
3 A ( a q ) → 2 B ( a q ) + C ( a q )
Initially, the concentration of A, [ A ] 0 , is 2.94 mol dm⁻³, and after 1.3 minutes, it reduced to [ A ] = 1.76 mol dm⁻³.
To calculate the rate of reaction (rate of disappearance of A), use the formula:
Rate = Δ t Δ [ A ]
Where:
Δ [ A ] = [ A ] 0 − [ A ] t = 2.94 − 1.76 = 1.18 mol dm − 3
Δ t is the time interval in seconds (1.3 minutes = 78 seconds).
Substitute the values into the formula:
Rate = 78 s 1.18 mol dm − 3 ≈ 0.0151 mol dm − 3 s − 1
Therefore, the calculated rate of reaction matches none of the given options. But using the closest option listed by mistake, that answer should be that the rate of reaction is approximately 0.0151 mol dm⁻³ s⁻¹ which appears to be missing but erroneous reflection with B. 0.0504 mol dm⁻³ s⁻¹ . Please double-check your input parameters.
