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Ch.14 - Chemical Kinetics
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All textbooksBrown 14th EditionCh.14 - Chemical KineticsProblem 113b

Chapter 14, Problem 113b

Platinum nanoparticles of diameter 2 nm are important catalysts in carbon monoxide oxidation to carbon dioxide. Platinum crystallizes in a face-centered cubic arrangement with an edge length of 3.924 Å. (b) Estimate how many platinum atoms are on the surface of a 2.0-nm Pt sphere, using the surface area of a sphere 14pr22 and assuming that the 'footprint' of one Pt atom can be estimated from its atomic diameter of 2.8 A .

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Hello everyone. So in this video we're trying to calculate for the number of gold atoms on the surface of a 5. nanometer gold sphere. And we're given the equation to solve for the surface area of a sphere right over here as well as the were given the diameter of a gold item right over here. All right. First things first, we're gonna go ahead and actually calculate the cross section area of a gold atom. So let's go ahead and just label this ask ross suck of gold atom. Alright, so the equation for this is that the area is equal to pi R squared And Pi is approximately 3.14. The radius is going to be 2.92 because that's the diameter and because we have diameter of course we need to go ahead and divide this by two. Actually does not forget our units Ekstrom divided by two. Alright, plugging that into my calculator. My numerical value will be six. Yes, of course. The radius squared again. Listen to my calculator. My numerical value is 6.69 and units be angstrom squared. Now we can go ahead and calculate for the surface area of the sphere. And the equation for that is given to us right over here. So we have that the area is equal to four pi R squared. So four times 4 pi is approximately 3. radius in this case is going to be 5. nanometers right over here. And then we're gonna go ahead and divide that by two. And we want our units to to stay consistent. So I'm gonna go ahead and convert my nanometers into angstrom. So that's going to be her 190 m. Of course, all of this is going to be squared. So, plugging that into my calculator, my new american value comes up to B 7850. And then my units will be ancient squirt. So finally we're gonna go ahead and calculate for the number of gold items. So we start off with the number of regions, software for the surface area right here. So we have the 7850 action. We want this unit to be canceled. So we can go ahead and use this. So 6.69 m squared for every one gold item. So then you can see here that the angstrom squared puppy canceled. Leaving us with the unit of gold atom, which is what we want. So then this will equal to 1, gold atoms. So that's going to be your final answer for this problem is that we have 1,173 quote atoms on the surface of a 5.0 nanometer gold sphere. Thank you all so much for watching
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Textbook Question

In a hydrocarbon solution, the gold compound (CH3)3AuPH3 decomposes into ethane (C2H6) and a different gold compound, (CH3)AuPH3. The following mechanism has been proposed for the decomposition of (CH3)3AuPH3:

Step 1: (CH3)3AuPH3 k1 k -1 (CH3)3Au + PH3 (fast)

Step 2: (CH3)3Au k2 C2H6 + (CH3)Au (slow)

Step 3: (CH3)Au + PH3 ¡k3 1(CH3)AuPH3 (fast)

(c) What is the molecularity of each of the elementary steps?

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Textbook Question

In a hydrocarbon solution, the gold compound (CH3)3AuPH3 decomposes into ethane (C2H6) and a different gold compound, (CH3)AuPH3. The following mechanism has been proposed for the decomposition of (CH3)3AuPH3:

Step 1: (CH3)3AuPH3 k1 k -1 (CH3)3Au + PH3 (fast)

Step 2: (CH3)3Au k2 C2H6 + (CH3)Au (slow)

Step 3: (CH3)Au + PH3 ¡k3 1(CH3)AuPH3 (fast)

(e) What is the rate law predicted by this mechanism?

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Textbook Question

In a hydrocarbon solution, the gold compound (CH3)3AuPH3 decomposes into ethane (C2H6) and a different gold compound, (CH3)AuPH3. The following mechanism has been proposed for the decomposition of (CH3)3AuPH3:

Step 1: (CH3)3AuPH3 k1 k -1 (CH3)3Au + PH3 (fast)

Step 2: (CH3)3Au k2 C2H6 + (CH3)Au (slow)

Step 3: (CH3)Au + PH3 ¡k3 1(CH3)AuPH3 (fast)

(f) What would be the effect on the reaction rate of adding PH3 to the solution of (CH3)3AuPH3?

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Textbook Question

Platinum nanoparticles of diameter 2 nm are important catalysts in carbon monoxide oxidation to carbon dioxide. Platinum crystallizes in a face-centered cubic arrangement with an edge length of 3.924 Å. (c) Using your results from (a) and (b), calculate the percentage of Pt atoms that are on the surface of a 2.0-nm nanoparticle.

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Textbook Question

One of the many remarkable enzymes in the human body is carbonic anhydrase, which catalyzes the interconversion of carbon dioxide and water with bicarbonate ion and protons. If it were not for this enzyme, the body could not rid itself rapidly enough of the CO2 accumulated by cell metabolism. The enzyme catalyzes the dehydration (release to air) of up to 107 CO2 molecules per second. Which components of this description correspond to the terms enzyme, substrate, and turnover number?

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Textbook Question

Enzymes are often described as following the two-step mechanism: E + S Δ ES 1fast2 ES ¡ E + P 1slow2 where E = enzyme, S = substrate, ES = enzyme9substrate complex, and P = product. (b) Molecules that can bind to the active site of an enzyme but are not converted into product are called enzyme inhibitors. Write an additional elementary step to add into the preceding mechanism to account for the reaction of E with I, an inhibitor.

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