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

Draw a schematic diagram of a system doing work without changing internal energy? State the law governs it?

How much heat energy is require to raise the temperature of $10\mathrm{g}$ of water by ${100}^{\mathrm{o}} \mathrm{C}$ $?$

The enthalpy of combustion of benzoic acid $\left({\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH}\right)$ at $298 \mathrm{K}$ and $1 \mathrm{atm}$ pressure is $-2546.0 \mathrm{kJ} {\mathrm{mol}}^{-1}$. What is $∆\mathrm{U}$ for the reaction ?

When an idea gas in a cylinder was compressed isothermally by a piston, the work done on the gas found to be $1.5\times {10}^4 \mathrm{J}$. During this process about

One mole of an ideal diatomic gas is expanded by heating state-I $\left(10 \mathrm{L}, 500 \mathrm{K}\right)$ to $\left(20 \mathrm{L}, 800 \mathrm{K}\right)$ against constant pressure $2 \mathrm{bar}$. Find the heat supplied in Joule.

(Given that $\mathrm{R}=\frac{25}{3}\mathrm{J}/\mathrm{mol}.\mathrm{K}$)

Round off your answer to the nearest integer.

Consider two states, $\mathrm{A}$ and $\mathrm{B}$, of a thermodynamic system. Let Path $1$ represent a reversible process for going from $\mathrm{A}$ to $\mathrm{B}$, while Path $2$ represents an irreversible process for the same. Let the work done, heat change, and entropy change for the two processes be denoted by ${\mathrm{dw}}_{\mathrm{rev} },{\mathrm{dq}}_{\mathrm{rev} },{\mathrm{dS}}_{\mathrm{rev} }$ and ${\mathrm{dw}}_{\mathrm{irrev} },{\mathrm{dq}}_{\mathrm{irrev} },{\mathrm{dS}}_{\mathrm{irrev} }$, respectively. It is observed that the relation ${\mathrm{dw}}_{\mathrm{rev}}<{\mathrm{dw}}_{\mathrm{irrev} }$ is obeyed. The correct statement is

Mathematical statement of the first law of thermodynamics is

The density of gas $\mathrm{A}$ is twice that of gas $\mathrm{B}$ at the same temperature. The molecular weight of gas $\mathrm{B}$ is thrice that of $\mathrm{A}$. The ratio of pressure acting on $\mathrm{A}$ and $\mathrm{B}$ will be

A system gives out $30 \mathrm{J}$ of heat and does $75 \mathrm{J}$ of work. What is the internal energy change?

The net work done by the system is :

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 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?

Find the change in the internal energy $\left(\mathrm{\Delta U}\right)$ of a closed system, when $\text{'}\mathrm{w}\text{'}$ denotes the  amount of work done by the system and $\text{'}\mathrm{q}\text{'}$ amount of heat is supplied to the system.