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hram777 [196]
2 years ago
7

How to draw Hess' Cycle for this question ?

Chemistry
1 answer:
NISA [10]2 years ago
7 0

Answer : The standard enthalpy of formation of ethylene is, 51.8 kJ/mole

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The formation reaction of C_2H_4 will be,

2C(s)+2H_2(g)\rightarrow C_2H_4(g)    \Delta H_{formation}=?

The intermediate balanced chemical reaction will be,

(1) C_2H_4(g)+3O_2(g)\rightarrow 2CO_2(g)+2H_2O(l)     \Delta H_1=-1411kJ/mole

(2) C(s)+O_2(g)\rightarrow CO_2(g)    \Delta H_2=-393.7kJ/mole

(3) H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(l)    \Delta H_3=-285.9kJ/mole

Now we will reverse the reaction 1, multiply reaction 2 and 3 by 2 then adding all the equations, we get :

(1) 2CO_2(g)+2H_2O(l)\rightarrow C_2H_4(g)+3O_2(g)     \Delta H_1=+1411kJ/mole

(2) 2C(s)+2O_2(g)\rightarrow 2CO_2(g)    \Delta H_2=2\times (-393.7kJ/mole)=-787.4kJ/mole

(3) 2H_2(g)+2O_2(g)\rightarrow 2H_2O(l)    \Delta H_3=2\times (-285.9kJ/mole)=-571.8kJ/mole

The expression for enthalpy of formation of C_2H_4 will be,

\Delta H_{formation}=\Delta H_1+\Delta H_2+\Delta H_3

\Delta H=(+1411kJ/mole)+(-787.4kJ/mole)+(-571.8kJ/mole)

\Delta H=51.8kJ/mole

Therefore, the standard enthalpy of formation of ethylene is, 51.8 kJ/mole

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2Na + 2H20 - 2NaOH + H2
Paul [167]

Answer: B) Ten moles of sodium hydroxide and five moles of hydrogen gas will be produced

Explanation: Got it right on USATestPrep

8 0
1 year ago
it takes 26.23 mL of a 1.008 M NaOh solution to neutralize a solution of an unknown monoprotic acid in 150.2 mL of solution. Wha
zhenek [66]

Answer:

Molarity of acid soln = 0.176M

Explanation:

Molarity of NaOH soln  x  Volume of NaOH soln = Molarity of acid soln  x  Volume of acid soln

=> 26.23ml  x  1.008M  =  150.2ml  x  Molarity of acid solution

=> Molarity of acid soln = (26.23ml)(1.008M)/(150.2ml) = 0.176M

7 0
3 years ago
In ideal gas equation calculations, expressing pressure in Pascals (Pa), necessitates the use of the gas constant, R, equal to _
Yuri [45]

Answer:

8.314\ \text{m}^3\text{Pa/mol K}

Explanation:

Let us find the unit of the gas constant R from the ideal gas equation. We substitute the units of the quantities rearrange them and get the units of the gas constant.

P = Pressure = Pa

V = Volume = \text{m}^3

n = Moles = mol

T = Temperature = K

PV=nRT\\\Rightarrow R=\dfrac{PV}{nT}\\\Rightarrow R=\dfrac{\text{Pa m}^3}{\text{mol K}}

Here, \text{Pa} is used so the gas constant value that must be used is 8.314\ \text{m}^3\text{Pa/mol K}.

3 0
3 years ago
one parsec equals 3.26 light years, where a light year is the distance light travels in one year. if the speed of light is 18600
Tpy6a [65]
Parsec is a unit of distance (as stated 1 Parsec = 3.26 light years, wihch is 3.26 times the distance run by light in one year).

That distance is:

1 parsec = 3.26 mi× 186,000 mi/s × 3600 s/h × 24 h/day × 365 day/ year × 1 year = 19,122,168,960,000.mi.

So, the question of <span>how many parsecs it takes for light to reach Mars from Earth does not make sense because parsecs is not a unit of time.
</span><span>
</span><span>
</span><span>You can calculate how many parsecs is equivalent to the distance between Mars and Earth, 60,000,000 km. For this you can first calculate the  equivalence of which you do in this way:
</span><span>
</span><span>
</span><span>60,000,000 km × 0,621 mi/km  × 1 parsec / ( 19,122,168,960,000 mi) = 1.94E-6 parsecs.
</span><span>
</span><span>
</span>

<span />

7 0
2 years ago
Solve for final product and show work for Na + NO3 ?
kirza4 [7]

Sodium (Na) is atomic number 11, so it has 1 valency

While Nitrate (NO₃) has valency 1

Sodium has an extra electron while nitrate needs an extra electron, sodium gives its electron to nitrate and forms a bond,

NaNO₃ (Sodium nitrate)

Happy to help :)

3 0
3 years ago
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