First Law of Thermodynamics

If $\mathrm{\Delta H}$ is the change in enthalpy and $\mathrm{\Delta E},$ the change in internal energy accompanying a gaseous reaction, then

Which among the following are true for an irreversible isothermal expansion of an ideal gas?

$\left(\mathrm{i}\right) \mathrm{W}=-\mathrm{Q}$
$\left(\mathrm{ii}\right) ∆\mathrm{U}=0$
$\left(\mathrm{iii}\right) \mathrm{\Delta H}\ne 0$
$\left(\mathrm{iv}\right) \mathrm{\Delta T}=0$

A heat engine absorbs heat ${\mathrm{Q}}_1$ at temperature ${\mathrm{T}}_1$ and heat ${\mathrm{Q}}_2$ at temperature ${\mathrm{T}}_2$. Work done by the engine is $\left({\mathrm{Q}}_1+{\mathrm{Q}}_2\right) \mathrm{J}$. This data

A gas undergoes change from state $\mathrm{A}$ to state $\mathrm{B}$. In this process, the heat absorbed and work done by the gas is $5 \mathrm{J} \text{and} 8 \mathrm{J}$, respectively. Now gas is brought back to $\mathrm{A}$ by another process during which $3 \mathrm{J}$ of heat is evolved. In this reverse process of $\mathrm{B} \mathrm{to} \mathrm{A}$.

Calculate the internal energy of a gas that absorbs $400 \mathrm{J}$ of heat and expands from$1\times {10}^{-3} {\mathrm{m}}^3$ to $3\times {10}^{-3} {\mathrm{m}}^3$ against a constant pressure 1 bar. 

The ratio K_p to K_c of a reaction is 24.63 L atm mol^–1 at 27°C. If heat of reaction at constant pressure is 98.8 kcal, calculate the heat of reaction (in kcal) at constant volume? (Report the value in the nearest integer)

(use $\mathrm{R}$ values $0.0821\mathrm{lit} \mathrm{atm} {\mathrm{mole}}^{-1}{\mathrm{k}}^{-1}$and $2\mathrm{X}{10}^{-3 }\mathrm{kcal} {\mathrm{mole}}^{-1}{\mathrm{k}}^{-1}$)

A gas is enclosed in a cylinder with a piston. Weights are added to the piston, giving a total mass of $2.20 \mathrm{kg}$. As a result, the gas is compressed and the weights are lowered $0.25 \mathrm{m}$. At the same time, $1.50 \mathrm{J}$ of heat is evolved from the system. Calculate the change in internal energy of the system and report the answer in the nearest integer value

For the reaction at $25°\mathrm{C}$,

${\mathrm{NH}}_3\left(\mathrm{g}\right)\to \frac{1}{2}{\mathrm{N}}_2\left(\mathrm{g}\right)+\frac{3}{2}{\mathrm{H}}_2\left(\mathrm{g}\right); ∆{\mathrm{H}}^{°}=11.04 \mathrm{kcal}$

Calculate ${\mathrm{\Delta U}}^{°}$ for the reaction at the given temperature.

(Note: Report your answer after multiplying with 100 and rounding up to the nearest integer value.)

The ratio K_p to K_c of a reaction is 24.63 L atm mol^–1 at 27°C. If heat of reaction at constant pressure is 98.6 kcal, what is the heat of reaction (in kcal)  at constant volume?

The specific heat of a certain substance is $0.86 \mathrm{J} {\mathrm{g}}^{-1} {\mathrm{K}}^{-1}$. Assuming ideal solution behavior, the energy required (in $\mathrm{J}$) to heat $10 \mathrm{g}$ of $1$ molal of its aqueous solution from $300 \mathrm{K}$ to $310 \mathrm{K}$ is closest to :

[Given: molar mass of the substance $=58 \mathrm{g} {\mathrm{mol}}^{-1}$; specific heat of water $=4.2 \mathrm{J} {\mathrm{g}}^{-1} {\mathrm{K}}^{-1}$]

According to IUPAC conventions work done on the surroundings is :

Which of the following statements are correct as per IUPAC sign convention ?

$∆\mathrm{U}=\mathrm{q}+\mathrm{W}$ is mathematical expression for

A gas is compressed adiabatically by doing work of $150 \mathrm{J}$ . What is the change in internal energy of the gas ?

A system goes from $A$ and $B$ by two different paths in the $P-V$ diagram as shown in figure. Heat given to the system in path $1$ is $1100\mathrm{J}$ . Also the work done by the system along path $1$ is more than path $2$ by $150\mathrm{J}$ . What is the heat exchanged by the system in path $2$ ?

Calculate amount of heat supplied to the gas to go from A to B If internal energy change of gas along AB is 10J. The given figure shows a change of state A to state C by two paths ABC and AC for an ideal gas :



 

Consider an ideal gas which undergoes a cyclic process as below:

${\text{ΔU}}_{\mathrm{BC}}=-5{\mathrm{kJmol}}^{-1}$

${\text{q}}_{\mathrm{AB}}=2{\mathrm{kJmol}}^{-1}$

${\text{W}}_{\mathrm{AB}}=-5{\mathrm{kJmol}}^{-1}$

${\text{W}}_{\mathrm{CA}}=3{\mathrm{kJmol}}^{-1}$

Then the Heat absorbed by the system during process CA is ____ ${\mathrm{kJmol}}^{-1}$

With a change in internal energy, $∆\mathrm{E}=30 \mathrm{L} \mathrm{atm}$, one mole of a non-ideal gas undergoes a change of state $\text{(2.0 atm, 3.0 L, 95 K)}$ $⟶$$\left(4.0 \mathrm{atm}, 5.0 \mathrm{L}, 245 \mathrm{K}\right)$ $\Delta \text{E}=\text{30.0 L atm}$. Then, change in enthalpy $\left(\Delta \text{H}\right)$ of the process in $\text{L atm}$ is_______________.

Calculate the increase in internal energy of system when 40 joule heat is supplied and the work done by a system is 8 joule