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2 years ago

Which of these actions would increase heat transfer between two objects?

1 answer:

5 0

Heat transfer is the phenomenon that occurs when the two objects are in the vicinity of each other and by increasing the area of their contact. Thus, option B is correct.

<h3>What is heat transfer?</h3>

Heat transfer is a process that flows the heat from one system to another, and is because of the difference in the temperature of the two objects that are part of the system.

The methods like conduction, convection, and radiation transfer the heat from the surface area to the other object. The heat gets transferred from the area of high to the low temperature.

Therefore, option B. by increasing the surface area the heat transfer increases.

Learn more about heat transfer here:

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Be sure to answer all parts. Styrene is produced by catalytic dehydrogenation of ethylbenzene at high temperature in the presenc

svlad2 [7]

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

8 0

3 years ago

What do you think might be different between fat molecules and carbohydrate and protein molecules?

dimulka [17.4K]

Answer:

Long answer

Proteins are the building blocks of the body, each and every organ muscle and skin and cells are made of proteins. They can also be used for providing energy to the body in a state where other energy sources aren't available.

Fats are stored energy blocks which can be used by the body at its own convenience whenever there is a deficit of energy in the body. They can also be directly burnt to give energy in cases where energy needs of the body are not met by dietary intake

Carbohydrates are the most convenient and preferable source of energy in the body and are easily converted to give out immidiate energy to the body, excess carbohydrates can be converted into fats and stored for later usage as and when required by the body.

Proteins, fats and carbohydrates have many secondary functions and roles in the human body. If you are keen to know anything more specific feel free to ask.

<h3>Short answer :</h3>

Fats are used for energy after they are broken into fatty acids. Protein can also be used for energy, but the first job is to help with making hormones, muscle, and other proteins.

7 0

1 year ago

Read 2 more answers

The magnetic field of an object exerts a force on any magnetic object around it.

11111nata11111 [884]

Answer: True

Explanation: this is true

8 0

2 years ago

Read 2 more answers

Briefly describe four ways that a beam can be strengthened?

lara31 [8.8K]

Answer:

1. Changing Beam Material

2. Corrugation

3. Changing Beam form

4. Steel Reinforcing Bars

Explanation:

Changing Beam Material

Some materials are stronger when used in beams than others. Beams made of steel for instance are stronger than beams made of wood. Therefore changing material can improve the strength of the beam. It is quite important to take into account the weights of the material though as different structures have different requirements.

Corrugation.

You can fold the beam into triangular shapes to increase strength. If you look at roofs you will notice that they are folded and this increased their strength. The same logic can be applied to beams.

Changing Beam Form

Another way to make Beams stronger is to change their form or rather their shape. Straight beams are not as strong as I-beams for instance. I-beams look like the capital letter I with the lines at both ends. I-beams are usually used in construction which shows that they are quite strong.

Steel Reinforcing Bars

When placed in concrete beams, Steel Reinforcing Bars which are also called Rebar can help strengthen a beam by helping it withstand the forces of tension. A concrete beam with Rebar inside it is known as Reinforced Concrete.

8 0

3 years ago

Which pair of samples contains the same number of oxygen atoms in each compound?0.20 mol Ba(OH)2 and 0.20 mol H2SO40.20 mol Br2O

Whitepunk [10]

Answer:

0.20 mol Br2O and 0.20 mol HBrO have the same number of oxygen atoms

Explanation:

In Ba(OH)2 there are 2 moles of O atoms in every mol of Ba(OH)2.

Number of O atoms in 0.20 moles Ba(OH)2 = 2*0.20 = 0.40 moles O atom

In H2SO4 there are 4 moles of O atoms for every mol of H2SO4.

Number of O atoms in 0.20 moles H2SO4 = 4*0.20 = 0.80 moles O atom

⇒ 0.20 mol Ba(OH)2 and 0.20 mol H2SO4 do <u>not</u> have the same number of oxygen atoms.

<em>0.20 mol Br2O and 0.20 mol HBrO</em>

In Br2O there is 1 mol of O atoms in every mol Br2O

Number of O atoms in 0.20 moles Br2O = 0.20*1 = 0.20 moles O atom

In HBrO there is 1 mol of O atom in every mol HBrO

Number of O atoms in 0.20 moles HBrO = 0.20 *1 = 0.20 moles O atom

⇒ in 0.20 moles Br2O and 0.20 moles HBrO we <u>have the same</u> number of oxygen atoms

0.20 moles of Oygen contains: = 0.20 * 6.022*10^23 = 1.2 *10^23 O atoms

In Fe2O3 there are 3 moles of O atoms in every mol of Fe2O3

Number of O atoms in 0.10 moles Fe2O3 = 0.10 * 3 = 0.30 moles O atom

In BaO there is 1 mol of O atoms in every mol BaO

Number of O atoms in 0.50 mol BaO = 1*0.50 = 0.50 moles O atom

⇒ 0.10 mol Fe2O3 and 0.50 mol BaO do <u>not</u> have the same number of oxygen atoms.

<em>0.10 mol Na2O and 0.10 mol Na2SO4</em>

In Na2O there is 1 mol of O atoms in every mol of Na2O

Number of O atoms in 0.10 mol Na2O = 1*0.10 = 0.10 moles O atom

In Na2sO4 there are 4 moles of O atoms in every mol of Na2SO4

Number of O atoms in 0.10 mol Na2SO4 = 4*0.10 = 0.40 moles O atom

⇒ 0.10 mol Na2O and 0.10 mol Na2SO4 do <u>not</u> have the same number of oxygen atoms.

4 0

3 years ago