Answer : The change in enthalpy for the following chemical reaction is, -90 kJ
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 given main reaction is,
![\Delta H=?](https://tex.z-dn.net/?f=%5CDelta%20H%3D%3F)
The intermediate balanced chemical reaction will be,
(1)
![\Delta H_1=175kJ](https://tex.z-dn.net/?f=%5CDelta%20H_1%3D175kJ)
(2)
![\Delta H_2=67kJ](https://tex.z-dn.net/?f=%5CDelta%20H_2%3D67kJ)
(3)
![\Delta H_3=-198kJ](https://tex.z-dn.net/?f=%5CDelta%20H_3%3D-198kJ)
Now we will reverse the reaction 2 and then adding all the equations, we get :
(1)
![\Delta H_1=175kJ](https://tex.z-dn.net/?f=%5CDelta%20H_1%3D175kJ)
(2)
![\Delta H_2=-67kJ](https://tex.z-dn.net/?f=%5CDelta%20H_2%3D-67kJ)
(3)
![\Delta H_3=-198kJ](https://tex.z-dn.net/?f=%5CDelta%20H_3%3D-198kJ)
The expression for enthalpy of change will be,
![\Delta H=\Delta H_1+\Delta H_2+\Delta H_3](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5CDelta%20H_1%2B%5CDelta%20H_2%2B%5CDelta%20H_3)
![\Delta H=(175kJ)+(-67kJ)+(-198kJ)](https://tex.z-dn.net/?f=%5CDelta%20H%3D%28175kJ%29%2B%28-67kJ%29%2B%28-198kJ%29)
![\Delta H=-90kJ](https://tex.z-dn.net/?f=%5CDelta%20H%3D-90kJ)
Therefore, the change in enthalpy for the following chemical reaction is, -90 kJ
Answer:
Helium
Explanation: The real gas that acts most like an ideal gas is helium. This is because helium, unlike most gases, exists as a single atom, which makes the van der Waals dispersion forces as low as possible. Another factor is that helium, like other noble gases, has a completely filled outer electron shell.
Answer:
The correct answer is 10.939 mol ≅ 10.94 mol
Explanation:
According to Avogadro's gases law, the number of moles of an ideal gas (n) at constant pressure and temperature, is directly proportional to the volume (V).
For the initial gas (1), we have:
n₁= 1.59 mol
V₁= 641 mL= 0.641 L
For the final gas (2), we have:
V₂: 4.41 L
The relation between 1 and 2 is given by:
n₁/V₁ = n₂/V₂
We calculate n₂ as follows:
n₂= (n₁/V₁) x V₂ = (1.59 mol/0.641 L) x 4.41 L = 10.939 mol ≅ 10.94 mol
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