Enthalpy

Consider the following reactions

(i) ${\text{H}}_{\left(\text{aq}\right)}^{+}+{\text{OH}}_{\left(\text{aq}\right)}^{-}\to {\text{H}}_2\text{O}\left(\mathrm{\ell \; }\right)$

$\Delta \text{H}=-{\text{X}}_1{\text{ k J mol}}^{-1}$

(ii) ${\text{H}}_2\left(\text{g}\right)+\frac{1}{2}{\text{O}}_2\left(\text{g}\right)\to {\text{H}}_2\text{O}\left(\ell \right)$

$\Delta \text{H}=-{\text{X}}_2{\text{ k J mol}}^{-1}$

(iii) ${\mathrm{CO}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)\to \mathrm{CO}\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

$\Delta \text{H}=-{\text{X}}_3{\text{ k J mol}}^{-1}$

(iv) ${\text{C}}_2{\text{H}}_2\left(\text{g}\right)+\frac{5}{2}{\text{O}}_2\left(\text{g}\right)\to 2{\text{CO}}_2\left(\text{g}\right)+{\text{H}}_2\text{O}\left(\ell \right)$

$\Delta \text{H}=+4{\text{X}}_4{\text{ k J mol}}^{-1}$

Enthalpy of formation of ${\text{H}}_2\text{O}\left(\ell \right)$

${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\left(\mathrm{l}\right)$ on complete combustion produce ${\mathrm{CO}}_2\left(\mathrm{g}\right) \mathrm{and} {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$ at $300 \mathrm{K}$. The difference between $∆\mathrm{H} \mathrm{and} ∆\mathrm{U}$ at this temperature is : 

Among the following standard enthalpy of formation is non-zero for

The relationship between $∆\mathrm{H}$ and $∆\mathrm{U}$ in a chemical reaction is $∆\mathrm{H} = ∆\mathrm{U} + \mathrm{P}∆\mathrm{V}$

The expression of work done by a system at constant temperature and pressure in a chemical reaction is $\mathrm{W}= {\mathrm{PV}}_1 - {\mathrm{PV}}_2$

Give the expression of work done by a system at constant temperature and pressure in a chemical reaction.

What is the relationship between $∆\mathrm{H}$ and $∆\mathrm{U}$ in a chemical reaction?

The enthalpy change of a reaction is independent of

Calculate the internal energy at $298 \mathrm{K}$ for the formation of one mole of ammonia, if the enthalpy change at constant pressure is $– 42.0 \mathrm{kJ} {\mathrm{mol}}^{–1}$.
(Given : $\mathrm{R} = 8.314 \mathrm{J} {\mathrm{K}}^{–1} {\mathrm{mol}}^{–1}$)

When a process takes place at constant volume, the heat absorbed or released is equal to the Enthalpy change.

Calculate the work done during the reactions represented by the following thermochemical equation at $300 \mathrm{K}$: 

${\mathrm{CH}}_4\left(\mathrm{g}\right)+2{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{CO}}_2\left(\mathrm{g}\right)+ 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

$(\mathrm{R} = 8.314 {\mathrm{JK}}^{–1} {\mathrm{mol}}^{–1})$

Define 'Enthalpy'

One mol of a non-ideal gas undergoes a change of state $(2.0 \mathrm{atm}, 3.0 \mathrm{L}, 95 \mathrm{K}) \to (4.0 \mathrm{atm}, 5.0 \mathrm{L}, 245 \mathrm{K})$ with a change in internal energy, $∆\mathrm{U}$$= 30.0 \mathrm{L} \mathrm{atm}$. The change in enthalpy $(∆\mathrm{H})$ of the process in $\mathrm{L} \mathrm{atm}$ is

A gas expands in volume from $2\mathrm{L}$ to $5\mathrm{L}$ against a pressure of $1$ atm at constant temperature. The work done by the gas will be

The enthalpy change for the reaction ${\mathrm{C}}_2{\mathrm{H}}_4 \left(\mathrm{g}\right) + {\mathrm{H}}_2 \left(\mathrm{g}\right) \to {\mathrm{C}}_2{\mathrm{H}}_6 \left(\mathrm{g}\right) \mathrm{is} - 620 \mathrm{J}$ when $100 \mathrm{mL}$ of ethylene and $100 \mathrm{mL}$ of$H_2$ react at$1$atm pressure. Calculate the pressure volume work and $∆\mathrm{U}$.

What are the signs of $∆\mathrm{S}$ and $∆\mathrm{H}$ for the following reaction? Explain with reasons.

$2\mathrm{H}\left(\mathrm{g}\right) \to {\mathrm{H}}_2\left(\mathrm{g}\right)$

Obtain the relationship between $△\mathrm{H}$ and $△\mathrm{U}$ for a chemical reaction.
 

Define enthalpy. At constant pressure show that $△\mathrm{H} = △\mathrm{U} + \mathrm{P}.△\mathrm{V}$.

The heat evolved in a reaction of $7.5 \mathrm{g}$ of ${\mathrm{Fe}}_2{\mathrm{O}}_3$ with enough $\mathrm{CO}$ is $1.164 \mathrm{kJ}$. Calculate $△\mathrm{H}°$ for the reaction ${\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right) + 3\mathrm{CO}\left(\mathrm{g}\right) \to 2\mathrm{Fe}\left(\mathrm{s}\right) + 3{\mathrm{CO}}_2\left(\mathrm{g}\right)$
 

Arrange in order of increasing enthalpy ${\mathrm{H}}_2\mathrm{O}\left(\mathrm{s}\right), {\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right), {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$.