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3 years ago

15

A large fraction of the thermal energy generated in the engine of a car is rejected to the air by the radiator through the circu

lating water. Should the radiator be analyzed as a closed system or an open system?

1 answer:

Rina8888 [55]3 years ago

5 0

Open system because there is mass (water) flowing through the system of interest (radiator)

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How would you describe what would happen to methane if the primary bonds were to break?

erastova [34]

Answer:

All the bonds in methane (CH4CH4) are equivalent, and all have the same dissociation energy.

The product of the dissociation is methyl radical (CH3CH3). All the bonds in methyl radical are equivalent, and all have the same dissociation energy.

The product of that dissociation is methylene (CH2CH2). All the bonds in methylene are equivalent, and all have the same dissociation energy.

The product of that dissociation is methyne (CHCH) .

The C-H bonds in methane do not have the same dissociation energy as C-H bonds in methyl radical, which in turn do not have the same dissociation energy as the C-H bonds in methylene, which are again different from the C-H bond in methyne.

If (by some miracle) you were able to get all four bonds in methane to dissociate absolutely simultaneously, they would all show the same dissociation energy… but that energy, per bond broken, would be different than the energy required to break just one C-H bond in methane, because the products are different.

(In this case, it’s CH4→C+4HCH4→C+4H versus CH4→CH3+HCH4→CH3+H.)

To alter hydrocarbons you add enough energy to break a C-H bond. Why does only one bond break? What concentrates the energy on one C-H bond?

the weakest CH bond is the one that breaks. in plain alkanes it has to do with the molecular orbital interactions between neighboring carbon atoms. look at propane for example. the middle carbon has two C-C bonds, and each of those C-C bonds is strengthened by slight electron delocalization from the C-H bonds overlapping with the antibonding orbitals of the adjacent carbons.

since the C-H bonds on the middle carbon donate electron density to both of its neighbors, those two are weakest.

one of them will break preferentially.

which one actually breaks depends on the reaction conditions (kinetics). frankly it's whichever one ramdomly approaches a nucleophile first. when the nucleophile pulls of one of the H's, the other C-H bonds start to share (delocalize) the negative charge across the whole molecule. so while the middle C feels the majority of the negative charge character, the other two C's take on a fair amount as well...

by the way, alkanes don't really like to break and form anions like that.

a better example would be something like isopropyl iodide, where the C-I bond breaks and the I carries away the electron pair, forming a carbocation (also not particularly stable, but more so than the carbanion).

7 0

3 years ago

A smooth sphere with a diameter of 6 inches and a density of 493 lbm/ft^3 falls at terminal speed through sea water (S.G.=1.0027

Pachacha [2.7K]

Given:

diameter of sphere, d = 6 inches

radius of sphere, r = $\frac{d}{2}$ = 3 inches

density, $\rho}$ = 493 lbm/ $ft^{3}$

S.G = 1.0027

g = 9.8 m/ $m^{2}$ = 386.22 inch/ $s^{2}$

Solution:

Using the formula for terminal velocity,

$v_{T}$ = $\sqrt{\frac{2V\rho g}{A \rho C_{d}}}$ (1)

$(Since, m = V\times \rho)$

where,

V = volume of sphere

$C_{d}$ = drag coefficient

Now,

Surface area of sphere, A = $4\pi r^{2}$

Volume of sphere, V = $\frac{4}{3} \pi r^{3}$

Using the above formulae in eqn (1):

$v_{T}$ = $\sqrt{\frac{2\times \frac{4}{3} \pir^{3}\rho g}{4\pi r^{2} \rho C_{d}}}$

$v_{T}$ = $\sqrt{\frac{2gr}{3C_{d}}}$

$v_{T}$ = $\sqrt{\frac{2\times 386.22\times 3}{3C_{d}}}$

Therefore, terminal velcity is given by:

$v_{T}$ = $\frac{27.79}{\sqrt{C_d}}$ inch/sec

3 0

3 years ago

In several sentences, please discuss:

Bezzdna [24]

Answer:

Everything is explained below in the Explanation section.

Explanation:

<em>a) TMDL stands for = Total Daily Maximum Loads</em>

TMDL is the measure of total maximum amount of pollutant allowed in the water body. TMDL is a important tool to maintain the quality of water and measure the aquatic pollution.

Whereas, the formula to calculate TMDL is as follows:

TMDL = Sum of waste load allocations (point source) + Sum of load allocations (non point sources and background) + Margin of Safety

<em>b) Dead Zones :</em>

Dead zones are zones which are termed as hypoxic which are low in oxygen because of the extreme aquatic pollution caused by human activities which in result deplete the oxygen level above the and below the oceans most required by the marine life. In addition, dead zones are those areas where oxygen is low and life in danger is high comparatively to other areas of oceans.

The main cause of that dead zones is because of eutrophication which means adding dangerous chemical nutrients in the water in exceeding amounts.

<em>c) Why Ammonia-nitrogen is detrimental to waterbodies: </em>

1. Ammonia nitrogen is a very toxic pollutant often found in landfills and sewage and waste products.

2. Ammonia nitrogen reduces the ability of water to disinfect its inhabitants and it reduces the purity. Furthermore, it changes the smell of the water and pollutes it.

3. Last but not the least, if you increase the concentration of ammonia nitrogen, the dissolved oxygen rate will be decreased and it has a inverse relation which is very dangerous to marine life underwater.

<em>d) Streeter-Phelps DO curve:</em>

Please refer to the attachment, I have attached the curve.

This curve is used to evaluate the dissolved oxygen in the water with varying distance.

It can be further studied from the curve that, how much loss sewage and other pollutants can endure upon the marine life.

8 0

3 years ago

Describe how the Rotary Engine works.

LekaFEV [45]

Answer:

Rotary engine was early known by the name of internal combustion engine. It convert heat from a high pressure of combustion. The main advantage of rotary engine is that it can be operate with less number of vibration. It works on the principle of converting pressure into rotating motion. In rotary engine the expansion pressure is applied on the flank rotor.

8 0

3 years ago

"Continuous duty" is defined as

larisa86 [58]

Answer:

operates at a substantially constant load for an indefinitely long time. ... Short-time duty: operates at a substantially constant load for a time that is definite, short, and specified. Varying duty: the loads and intervals of operation change.

Explanation:

4 0

3 years ago

Read 2 more answers