Question

Constants | Periodic Table Consider the reaction A+2B⇌C whose rate at 25 ∘C was measured using...

Constants | Periodic Table

Consider the reaction

A+2B⇌C

whose rate at 25 ∘C was measured using three different sets of initial concentrations as listed in the following table:
 Trial [A] (M) [B] (M) Rate (M/s) 1 0.50 0.050 1.5×10−2 2 0.50 0.100 3.0×10−2 3 1.00 0.050 6.0×10−2

Part a

Calculate the initial rate for the formation of C at 25 ∘C, if [A]=0.50M and [B]=0.075M.

Express your answer to two significant figures and include the appropriate units.

View Available Hint(s)

initial rate =

?

Constants | Periodic Table

Learning Goal:

To calculate average and relative reaction rates.

Reaction rate can be defined either as the increasein the concentration of a product per unit time or as the decrease of the concentration of a reactant per unit time. By definition, reaction rate is a positive quantity.

In the reaction X→2Y, for example, Y is being produced twice as fast as X is consumed and thus

rate of X=12(rate of Y)

Each rate can be expressed as the change in concentration over the change in time, Δt:

−Δ[X]Δt=12(Δ[Y]Δt)

 Time (s) 0 10.0 20.0 30.0 40.0 50.0 [P2O5] (mol L−1) 0 2.90×10−3 5.90×10−3 7.70×10−3 8.90×10−3 9.50×10−3

Part e

What is the average rate of consumption of H+ during the same time interval?

View Available Hint(s)

Rate of consumption of H+ =

Submit

Part 1)

Here, rate = k[A]2 [B]

From experiment (1)

1.5 x 10-2 = k x 0.52 x 0.05

Therefore, k= (1.5 x 10-2) / (0.52 x 0.05) = 1.2 M-2s-1

Now, initial rate for the formation of C at 25 C, if [A] = 0.50M and [B] = 0.075M can be calculated as,

Rate = 1.2 x [0.5]2 x [0.075] = 0.022 M/s

Part 2)

Rate of formation of P2O5 = −Δ[A]/Δt = [(8.90×10−3)-( 2.90×10−3)] / (40-10)

= (6 × 10−3) / 30 = 2 x 10-4 M/s

Part 3)

Here, this part is incomplete, the average rate of consumption of Br- is not provided.

If you know the average rate of consumption of Br-, then according to the following reaction,

5Br-(aq) + BrO3-(aq) + 6H+(aq) → 3Br2(aq) + 3H2O (l)

Average rate of consumption of H+ = average rate of consumption of Br- x (6/5)

Use comment box if further clarifications required

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