Given $\Delta H_{f}{ }^{\circ}$ for $CO _{2}(g), CO (g)$ and $H _{2} O (g)$ are $ -393.5, -110.5 \text { and } -241.8 kJ mol ^{-1}$, respectively. The $\Delta H_{f}^{\circ}$ [in $kJ mol ^{-1}$ ] for the reaction $CO _{2}(g)+ H _{2}(g) \longrightarrow CO (g)+ H _{2} O (g)$ is
- 524.1
- -262.5
- -41.7
- 41.2
The Correct Option is D
Solution and Explanation
$\Delta H_{f}^{\circ}=(\Delta H)_{\text {products }}-(\Delta H)_{\text {reactants }}$
Hence, $\Delta H_{f}{ }^{\circ}=\left[\Delta H_{f_{ CO }}+\Delta H_{f_{ H _{2} O }}\right]-\left[\Delta H_{f CO _{2}}\right] \ldots( i )$
Given, $\Delta H_{f CO _{2}(s)}^{\circ}=-393.5 kJ mol ^{-1}$
$\Delta H_{f CO }^{\circ}=-110.5 \,kJ mol ^{-1}$
$\Delta H_{f H _{2} O }^{\circ}=-241.8 kJ mol ^{-1}$
Put there value in equation
$\Delta H_{f^{\circ}}=-110.5-241.8+393.5=41.2$
Top Questions on Enthalpy change
- Identify the incorrect statement from the following:
- NEET (UG) - 2024
- Chemistry
- Enthalpy change
- Arrange the following elements in increasing order of first ionization enthalpy:
Li, Be, B, C, N
Choose the correct answer from the options given below:- NEET (UG) - 2024
- Chemistry
- Enthalpy change
- A transition metal 'M' among Sc, Ti, V , Cr, Mn and Fe has the highest second ionisation enthalpy. The spin only magnetic moment value of M+
ion is ______ BM (Near integer) (Given atomic number Sc : 21, Ti : 22, V : 23, Cr : 24, Mn : 25, Fe : 26)- JEE Main - 2024
- Chemistry
- Enthalpy change
- $\Delta_{vap}H^\circ$ for water is $+40.49 \, \text{kJ mol}^{-1}$ at 1 bar and $100^\circ\text{C}$. Change in internal energy for this vaporisation under same condition is .............. kJ mol$^{-1}$. (Integer answer)
(Given R = 8.3 J K$^{-1}$ mol$^{-1}$)- JEE Main - 2024
- Chemistry
- Enthalpy change
- When equal volume of 1M HCl and 1M H$_2$SO$_4$ are separately neutralized by excess volume of 1M NaOH solution, X and Y kJ of heat is liberated respectively. The value of Y/X is ____.
- JEE Main - 2024
- Chemistry
- Enthalpy change
Questions Asked in TS EAMCET exam
The ratio of the radii of two solid spheres of same mass in 2:3. The ratio of the moments of inertia of the spheres about their diameters is:
- TS EAMCET - 2023
- rotational motion
If (-c, c) is the set of all values of x for which the expansion is (7 - 5x)-2/3 is valid, then 5c + 7 =
- TS EAMCET - 2023
- Algebra of Complex Numbers
The general solution of the differential equation (x2 + 2)dy +2xydx = ex(x2+2)dx is
- TS EAMCET - 2023
- Differential equations
If i=√-1 then
\[Arg\left[ \frac{(1+i)^{2025}}{1+i^{2022}} \right] =\]- TS EAMCET - 2023
- Trigonometric Identities
If nCr denotes the number of combinations of n distinct things taken r at a time, then the domain of the function g (x)= (16-x)C(2x-1) is
- TS EAMCET - 2023
- permutations and combinations
Concepts Used:
Enthalpy change
Enthalpy Change refers to the difference between the heat content of the initial and final state of the reaction. Change in enthalpy can prove to be of great importance to find whether the reaction is exothermic or endothermic.
Formula for change in enthalpy is:-
dH = dU + d(PV)
The above equation can be written in the terms of initial and final states of the system which is defined below:
UF – UI = qP –p(VF – VI)
Or qP = (UF + pVF) – (UI + pVI)
Enthalpy (H) can be written as H= U + PV. Putting the value in the above equation, we obtained:
qP = HF – HI = ∆H
Hence, change in enthalpy ∆H = qP, referred to as the heat consumed at a constant pressure by the system. At constant pressure, we can also write,
∆H = ∆U + p∆V
Standard Enthalpy of Reaction
To specify the standard enthalpy of any reaction, it is calculated when all the components participating in the reaction i.e., the reactants and the products are in their standard form. Therefore the standard enthalpy of reaction is the enthalpy change that occurs in a system when a matter is transformed by a chemical reaction under standard conditions.