What was the molecular geometry for SC16?

Answer:

a) ΔHºrxn = 116.3 kJ, ΔGºrxn = 82.8 kJ,  ΔSºrxn =  0.113 kJ/K

b) At 753.55 ºC or higher

c )ΔG =  1.8 x 10⁴ J

    K = 8.2 x 10⁻²

Explanation:

a)                                 C6H5−CH2CH3  ⇒  C6H5−CH=CH2  + H₂

ΔHf kJ/mol                    -12.5                           103.8                      0

ΔGºf kJ/K                        119.7                         202.5                      0

Sº J/mol                          255                          238                      130.6*

Note: This value was not given in our question, but is necessary and can be found in standard handbooks.

Using Hess law to calculate  ΔHºrxn we have

ΔHºrxn  = ΔHfº C6H5−CH=CH2 +  ΔHfº H₂ - ΔHºfC6H5−CH2CH3

ΔHºrxn =     103.8 kJ + 0 kJ  - (-12.5 kJ)

ΔHºrxn = 116.3 kJ

Similarly,

ΔGrxn = ΔGºf C6H5−CH=CH2 +  ΔGºfH₂ - ΔGºfC6H5CH2CH3

ΔGºrxn=   202.5 kJ + 0 kJ - 119.7 kJ  = 82.8 kJ

ΔSºrxn = 238 J/mol + 130.6 J/mol -255 J/K = 113.6 J/K = 0.113 kJ/K

b) The temperature at which the reaction is spontaneous or feasible occurs when ΔG becomes negative and using

ΔGrxn =  ΔHrxn -TΔS

we see that will happen when the term  TΔS  becomes greater than ΔHrxn since ΔS  is positive  , and so to sollve for T we will make ΔGrxn equal to zero and solve for T. Notice here we will make the assumption that  ΔºHrxn and ΔSºrxn remain constant at the higher temperature  and will equal the values previously calculated for them. Although this assumption is not entirely correct, it can be used.

0 = 116 kJ -T (0.113 kJ/K)

T = 1026.5 K  =  (1026.55 - 273 ) ºC = 753.55 ºC

c) Again we will use

                       ΔGrxn =  ΔHrxn -TΔS

to calculate ΔGrxn   with the assumption that ΔHº and ΔSºremain constant.

ΔG =  116.3 kJ - (600+273 K) x 0.113 kJ/K =  116.3 kJ - 873 K x 0.113 kJ/K

ΔG =  116.3 kJ - 98.6 kJ =  17.65 kJ = 1.8 x 10⁴ J ( Note the kJ are converted to J to necessary for the next part of the problem )

Now for solving for K, the equation to use is

ΔG = -RTlnK and solve for K

- ΔG / RT = lnK  ∴ K = exp (- ΔG / RT)

K = exp ( - 1.8 x 10⁴ J /( 8.314 J/K  x 873 K)) = 8.2 x 10⁻²

Final answer:

The change in enthalpy, entropy, and free energy were calculated for the dehydrogenation reaction of ethylbenzene into styrene. The reaction was found to be endothermic and results in a decrease in overall disorder. Under the given conditions, the reaction will never be spontaneous.

Explanation:

The processes involved in the production of styrene from ethylbenzene are fairly complex and require knowledge of thermodynamics. We'll begin with ΔH°rxn, which is found by subtracting the enthalpy (ΔH) of the reactants from that of the products: ΔH°rxn = [ΔH°f(styrene)] - [ΔH°f(ethylbenzene)] = 103.8 kJ/mol - (-12.5 kJ/mol) = 116.3 kJ/mol. This means the reaction is endothermic, as heat is absorbed.

The change in entropy ΔS°rxn, obtained likewise, is [S°(styrene) - S°(ethylbenzene)] = (238 J/mol·K - 255 J/mol·K) = -17 J/mol·K. This indicates a decrease in disorder in the system.

With these, we can calculate the change in free energy ΔG°rxn at a given temperature (T) using the equation ΔG°rxn = ΔH°rxn - TΔS°rxn. Substituting the known values at 298 K, ΔG°rxn = 116.3 kJ/mol - (298 K)(-17 J/mol·K) = 121.2 kJ/mol, indicating a non-spontaneous reaction.

For the reaction to be spontaneous, ΔG°rxn must be less than zero. Solving for T in the above equation with ΔG°rxn = 0, yields T = ΔH°rxn / ΔS°rxn = 116.3 kJ/mol / -17 J/mol·K ≈ -6840 K. This value is negative, implying the reaction is never spontaneous under the given conditions.

Learn more about Thermodynamics of Styrene Production here:

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Answer:

The final pressure is 0.788 atm (option b).

Explanation:

Boyle's law says that the volume occupied by a given gaseous mass at constant temperature is inversely proportional to pressure. That is: if the pressure increases, the volume decreases, while if the pressure decreases, the volume increases. This is expressed mathematically as the product of pressure times volume equal to a constant value:

P*V=k

Assuming a certain volume of gas V1 that is at a pressure P1 at the beginning of the experiment, by varying the volume of gas to a new value V2, then the pressure will change to P2, and it will be fulfilled:

P1*V1=P2*V2

In this case:

• P1= 2.14 atm
• V1= 3 L
• P2= ?
• V2= 8.15 L

Replacing:

2.14 atm*3 L= P2* 8.15 L

Solving:

0.788 atm= P2

The final pressure is 0.788 atm (option b).

Answer:

We know that in the decay process the sum of molecular number as well as molecular weight should be constant.

The following three reaction are as follows

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Explanation:

Answer:

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Explanation:

Answer:

Explanation:We known that Earths energy machine is driven by sunlight which acts as fuel for this machine and to strike a balance between outgoing long wave radiation and short wave radiation there are many factors which are involved in this process.Sun emits this energy in the form of short wave radiation because of the huge energy it has and short wave radiation are higher in energy.Hence, they reach the earth surface mostly as visible and UV rays.After reaching the earths surface what happens with these rays is that they get absorbed by the clouds and other constituents of Earth.

Now, this energy needs to be emitted back in to space in order to balance out the energy budget of earth and that is why this energy is emitted back as long wave radiation which have less energy and also earth has less energy unlike the sun.Loss of this energy is essential as Earth looses most of its energy through this and results in cooling.But when this OLR decreases it should be a cause of concern for us.

This imbalance is caused by a wide range of different human induced activities which has a cumulative effect on the temperature of earth.These activities gives rise to a huge gain in the CO2 concentration which is why this word has gain so much popularity and a cause of widespread concern for us.At community level we contribute to this heating by increasing usage of personal automobiles rather than going for public transport , advancement in technology has greatly changed our lifestyles making it more simpler and easier but this demands more energy consumption.Landscape changes are one of the most important because its taking place at a faster rate.Most of the land being cleared off to built new houses which means clearing off the existing vegetation which leads to temperature rise.Setting up of Industry depending on its type can reduce the amount of OLR escaping the surface by introducing more amount of GHGs in to the atmosphere.

Its these small communities which add up to become the entire human population causing a massive damage and hence at community level if people realize and take necessary steps things will start to change.

Asnwer : Empirical formula of a compound is :

Given information : C = 64.3 % , H = 7.2 % , O = 28.5 %

Step 1 : Convert the given percentage (%) to grams.

Explanation : Let the total mass of the compound be 100 grams.

Mass of C = 64.3 g

Mass of H = 7.2 g

Mass of O = 28.5 g

Step 2 : Convert the grams of each compound to moles.

Molar mass of C = 12.0g/mol  

Molar mass of H = 1.0 g/mol

Molar mass of O = 16.0g/mol

Moles of C = 5.36 mol

Moles of H = 7.2 mol

Moles of O = 1.78 mol

Step 3 : Find the mole ratio of C , H and O

Mole ratio is calculated by dividing the mole values by the smallest value.

Mole of C = 5.36 mol , Mole of H = 7.2 mol , Mol of O = 1.78 mol

Out of the three mole values , mole value of O that is 1.78 mol is less , so we divide all the mole values by 1.78 mol.

C : H : O = 3 : 4 : 1

So empirical formula of the compound is or