Chemistry, 08.04.2020 00:01 chl75

The following data were obtained for the reaction 2A + B → C where rate = Δ[C]/Δt [A](M) [B](M) Initial Rate (M/s) 0.100 0.0500 2.13 × 10–4 0.200 0.0500 1.70 × 10–2 0.400 0.100 1.36 × 10–1 What is the value of the rate constant?

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Answer from: jordandabrat

Answer : The value of the rate constant 'k' for this reaction is $2.67\times 10^{2}M^{-2}s^{-1}$

Explanation :

Rate law is defined as the expression which expresses the rate of the reaction in terms of molar concentration of the reactants with each term raised to the power their stoichiometric coefficient of that reactant in the balanced chemical equation.

For the given chemical equation:

$2A+B\rightarrow C$

Rate law expression for the reaction:

$\text{Rate}=k[A]^a[B]^b$

where,

a = order with respect to A

b = order with respect to B

Expression for rate law for first observation:

$2.13\times 10^{-4}=k(0.100)^a(0.0500)^b$ ....(1)

Expression for rate law for second observation:

$1.70\times 10^{-2}=k(0.200)^a(0.0500)^b$ ....(2)

Expression for rate law for third observation:

$1.36\times 10^{-1}=k(0.400)^a(0.100)^b$ ....(3)

Dividing 2 by 1, we get:

$\frac{1.70\times 10^{-2}}{2.13\times 10^{-4}}=\frac{k(0.200)^a(0.0500)^b}{k(0.100)^a(0.0500)^b}\\\\80=2^a\\\\\log 80=a\times \log 2\\\\a=6$

Dividing 3 by 2 and put value of a = 6, we get:

$\frac{1.36\times 10^{-1}}{1.70\times 10^{-2}}=\frac{k(0.400)^6(0.100)^b}{k(0.200)^6(0.0500)^b}\\\\8=2^{(b+6)}\\\\b+6=3\\\\b=-3$

Thus, the rate law becomes:

$\text{Rate}=k[A]^a[B]^b$

$\text{Rate}=k[A]^6[B]^{-3}$

Now, calculating the value of 'k' by using any expression.

$2.13\times 10^{-4}=k(0.100)^6(0.0500)^{-3}$

$k=2.67\times 10^{2}M^{-2}s^{-1}$

Hence, the value of the rate constant 'k' for this reaction is $2.67\times 10^{2}M^{-2}s^{-1}$

Answer from: Quest

remember that hf is only the energy of one photon. not two. not three. one. 1) 5.12 * 10^3 photons find the energy of one photon, then determine how many photons are needed to reach the sensitivity. e = hf = (6.626 * 10^-34 js)(5.95 * 10^19 hz) = 3.94247 * 10^-14 j per photon (2.02 * 10^-10 j) / (3.94247 * 10^-14 j/photon) = 5123.69149 photons round to three sig figs. 2) 5.77 * 10^-17 j energy of pulse = energy per photon * number of photons = hfn = (6.626 * 10^-34 js)(1.66 * 10^13 hz)(5250) = 5.774559 * 10^-17 j round to three sig figs. 3) 4.07 * 10^8 kj/mol 10^12 pm = 1 m c = fλ f = c/λ e = hf = hc/λ = [(6.626 * 10^-34 js)(3.00 * 10^8 m/s) / (2.94 * 10^-12 m)](1 kj/1000 j)(6.02 * 10^23 photons/mol) = 40702571.4 kj/mol round to three sig figs. 4) 9.94 * 10^-1 m e = hc/λ λ = hc / e = (6.626 * 10^-34 js)(3.00 * 10^8 m/s) / (2.00 * 10^-25 j) = 0.9939 m round to three sig figs. 5) 9.06 * 10^3 photons energy of pulse = energy per photon * number of photons number of photons = energy of pulse / energy per photon = energy of pulse / (hf) = (3.87 * 10^-13 j) / [(6.626 * 10^-34 js)(6.45 * 10^16 hz)] = 9055.23695 photons round to three sig figs. 6) 2.78 * 10^-15 j this is problem 1, except in reverse. sensitivity = minumum number of photons * energy per photon = (5930)(6.626 * 10^-34 js)(7.077 * 10^14 hz) = 2.78070758 × 10^-15 j round to three sig figs.

Answer from: Quest

I’m really not sure what’s the answer. sorry

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The following data were obtained for the reaction 2A + B → C where rate = Δ[C]/Δt [A](M) [B](M) Init...

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