Bài tập lớn Hóa lý 2

Khảo sát hấp phụ của nitrogen trên bề mặt chất bằng phương trình, khảo sát tốc độ phản ứng bằng phần mềm matlab

VIETNAM NATIONAL UNIVERSITY HO CHI MINH CITYHO CHI MINH CITY UNIVERSITY OF TECHNOLOGY

FACULTY OF CHEMICAL ENGINEERING

GROUP ASSIGNMENT PROJECTCourse: Physical Chemistry 2 (CH2109) – 222

Group No: 222 – A01 – 06

Lecturer: Students:

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Ho Chi Minh City – 04/2023

I Content of Questions and Solutions

Question 1: Using the following data of the adsorption of N2 on solid X at -196oC, inwhich: x= P/P0: relative pressure, V: volume adsorbed cc (STP)/g:

- Plot the adsorption isotherm

- Calculate the specific surface area of the solid X.

Solution 1: The diagram is plotted basing on the Brunauer-Emmett-Teller equation (BET)

which is chosen thanks to be suitable for given information about P/P0 and V BETequation: P/ P0

V(1- P/ P0)=1vmC+

vmC is b Through linearregression method, we can identify:

{ C-1vmC = a ≈ 0.077121

The specific surface area between solid X and gas N2 is identified by equation

vm=12.3ml ; N=6.022×1023; A=16.2×10-20mV=22.4L/ mol =22.4×103 ml/ mol ; m=1g (assume)

Certified reference materials for porosity properties

First we assume vm is unchanged even and calculate new molar colume of N2 at 77K.V77K=nRT

1×0.082×77

Question 2: Search data from the Internet for the above battery and:

- Describe the composition of the battery

- Write half-reaction at the negative electrode of a cell in the battery- Write half-reaction at the positive electrode of a cell in the battery- Calculate the standard emf of a cell in the battery

Solution 2:

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Question 3: Your company has two liquid streams available containing solutes that are

not profitably marketable at the present time One stream contains an aqueous solution ofA The second stream contains an aqueous solution of species B Species A can reacteither with species B or with itself according to the following stoichiometric equations andrate expressions:

(a) At a specific temperature (T): k1= 0.01 (M-1.min-1), k2= 0.01 (M-1.min-1), k3= 0.002 (M-0.5).

When a 1L aqueous solution containing 1M of A mixed quickly with a 1L aqueous

solution containing 1M of B:

- Plot the concentration of V as a function of reaction time (up to 90% A reacted)

- Plot the concentration of W as a function of reaction time (up to 90% A reacted)

(b) You have two beakers containing samples of the two streams and desire to carry out a

small-scale laboratory experiment in which you maximize the formation of species V Inwhat manner should you carry out this experiment; that is, in what order and at whatrate would you add each beaker of the reactants to an empty container?

(c) If the activation energies for the rate constants k1, k2, and k3 are 90, 40, and 50 kJ/mol,

respectively, what additional statements can you make regarding the operatingtemperature recommended for maximizing production of species V?

Solution 3:

a We have:d CA

dt = - k1CACB- 2 k2CA21+ k3CV0.5d CB

Using matlab to calculate the change in the concentration of 4 substances by time,with the value shown below.

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The change in the concentration of A, B, V and W by time

After 352.2987 seconds, 90% of A reacted

b To maximize the formation of species V, we need to favor the reaction betweenspecies A and B over the reaction of A with itself This is because the formation of V isdirectly proportional to the rate of the reaction between A and B, and inverselyproportional to the rate of the reaction of A with itself.

The stoichiometric equations and rate expressions given are:

From these equations, we can see that the formation of V depends on theconcentration of both A and B, as given by the rate expression rV = k1CACB The rate ofthe reaction between A and B can be increased by increasing the concentrations of A andB, and by increasing the rate constant k1.

On the other hand, the formation of W depends only on the concentration of A, asgiven by the rate expression rW =2 k2CA

1+ k3C0.5V The rate of the reaction of A with itself can beincreased by increasing the concentration of A, the rate constant k2, and the square rootof the concentration of V, which is given by CV0.5.

To maximize the formation of V, we need to control the addition of A so that the rateof the reaction between A and B is faster than the rate of the reaction of A with itself Thiscan be achieved by limiting the concentration of A in the reaction mixture so that thesecond reaction does not occur to a significant extent.

Here's how we can carry out the experiment in a step-wise manner to maximize theformation of V:

1 Begin by adding the aqueous solution of species B to an empty container.

2 Start stirring the solution and maintain a constant stirring rate throughout theexperiment.

3 Slowly add the aqueous solution of species A to the container, while monitoring theconcentration of V.

4 Control the addition of A so that the rate of the reaction between A and B is faster thanthe rate of the reaction of A with itself This can be achieved by adjusting the rate ofaddition of A to keep the concentration of A low compared to the concentration of B.5 Continue adding A until the maximum concentration of V is reached.

It's important to note that the rate of the reaction between A and B is given byrV = k1CACB, which means that the concentration of both A and B should be kept as highas possible to maximize the rate of the reaction However, we need to be careful not to

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add too much A, as it could result in the second reaction taking place and reducing theyield of V.

c If the activation energies for the rate constants k1, k2, and k3 are 90, 40, and 50 kJ/mol,respectively

Applying Arrhenius equation:

k2 = - EaR (1T2 -

1 Choose k1’ = 2k1 = 0.02 M-1min-1

⟹(1T2 1

⟹(1T2 1

-T1)= -1.015×10-4⟹ k2'=0.0163 M-1min-1; k3'=0.00368 M-0.5

CV' =0,308202 M , CW' =0,095899 M

C'W+ C'V =

0,095899+0,308202=0,762656So temperature increase  Selectivy increases