List of top Chemistry Questions on Work done in Thermodynamics

An ideal gas (\(0.5\) mol), initially at \(2\) bar pressure, is compressed at a constant temperature of \(600\ \text{K}\) in two steps: first, against a constant external pressure of \(P\) bar \((2 < P < 8)\), and then against constant external pressure of \(8\) bar. At each step, the compression is stopped only when the pressure of the gas becomes equal to the external pressure. The total work done on the gas in these steps is \(W\). Considering all possible values of \(P\ (2 < P < 8)\) and taking the gas constant as \(R\) (in \(\text{J K}^{-1}\text{mol}^{-1}\)), the minimum value of \(|W|\) (in J) is equal to:

At 27^C, 1.6 g of O$_2$ gas at 5 atm expands isothermally against a constant external pressure of 1 atm. The work done (in J) is (1 L-atm = 100 J):

For a spontaneous process at constant temperature and pressure, the change in Gibbs free energy ($\Delta G$) is

Which of the following is true for entropy?

In an isothermal expansion of an ideal gas, the heat supplied to the gas is:

For the complete combustion of ethanol, \(\text{C}_2\text{H}_5\text{OH}(l) + 3\text{O}_2(g) \rightarrow 2\text{CO}_2(g) + 3\text{H}_2\text{O}(l)\), the amount of heat produced as measured in bomb calorimeter is \(1364.47 \text{ kJ mol}^{-1}\) at \(25^\circ\text{C}\). Assuming ideality the enthalpy of combustion, \(\Delta H_C\), for the reaction will be \((\text{R} = 8.314 \text{ JK}^{-1}\text{mol}^{-1})\)

The value of enthalpy change (\(\Delta H\)) for the reaction \(\text{C}_2\text{H}_5\text{OH}(l) + 3\text{O}_2(g) \rightarrow 2\text{CO}_2(g) + 3\text{H}_2\text{O}(l)\), at \(27^\circ\text{C}\) is \(-1366.5 \text{ kJ mol}^{-1}\). The value of internal energy change for the above reaction at this temperature will be

In a cyclic \(pV\) process forming a square loop from \((p = 1 \text{ atm}, V = 2\text{L})\) to \((p = 3 \text{ atm}, V = 4\text{L})\), then, the net heat absorbed by the gas is:

The temperature in K at which \(\Delta G = 0\), for a given reaction with \(\Delta H = -20.5 \text{ kJ mol}^{-1}\) and \(\Delta S = -50.0 \text{ J K}^{-1} \text{ mol}^{-1}\) is:

The standard enthalpies of formation of $\mathrm{CH_4(g)}$, $\mathrm{CO_2(g)}$ and $\mathrm{H_2O(l)}$ are $-78$, $-395$ and $-288\ \mathrm{kJ\ mol^{-1}}$ respectively. Calculate $\Delta H$ for: \[ \mathrm{2CH_4(g) + 4O_2(g) \rightarrow 2CO_2(g) + 4H_2O(l)} \] }

Find the work done by a gas that expands from \(0.2\,\text{dm}^3\) to \(0.8\,\text{dm}^3\) against a constant pressure of \(2\) bar.

Which of the following is not a property of a thermodynamic system?

The mathematical statement of the first law of thermodynamics with the usual notation is

1 g of graphite is burnt completely in excess oxygen at 298K and 1 atmospheric pressure in a bomb calorimeter. During the reaction, the temperature raises from 298K to 299K. If the heat capacity of the bomb calorimeter is 20.7 kJ K\(^{-1}\), what is the enthalpy of combustion of C(gr)? (Atomic mass of carbon is 12 g mol\(^{-1}\))

In a free expansion of a gas

The first law of thermodynamics can be stated as

For the reaction CO(g) + \(\frac{1}{2}\) O\(_2\)(g) \(\rightarrow\) CO\(_2\)(g) Which one of the statement is correct at constant T and P?

\( \Delta G \) for \( 3\text{X}_{(g)} + 2\text{Y}_{(g)} \rightarrow 3\text{Z}_{(g)} \) at 293 K is
( \( \Delta H^\circ = -13\,\text{kJ mol}^{-1} \), \( \Delta S^\circ = -45\,\text{J mol}^{-1}\text{K}^{-1} \) )

Calculate the work done in joule if 1 mole of an ideal gas compressed from volume 24 dm$^3$ to 13 dm$^3$ at constant external pressure 3 bar.

Calculate the work done if 1 mole of gas compressed isothermally and reversibly at 300 K from initial pressure 1 bar to final pressure 2 bar [$R=8.314~J~K^{-1}mol^{-1}$]

For a certain reaction $\Delta H = -225$ kJ and $\Delta S = -150$ J K$^{-1}$. Find the temperature so that $\Delta G$ is zero.

Which from following is an example of an intensive property of the system?

Calculate the work done in the oxidation of one mole $HCl_{(g)}$ at 27$^\circ$C, according to reaction.
$4HCl_{(g)} + O_{2(g)} \rightarrow 2Cl_{2(g)} + 2H_2O_{(g)}$
(R = 8.314 J K$^{-1}$ mol$^{-1}$)

Calculate the constant external pressure required to expand 2 moles of an ideal gas from volume $15\text{dm}^3$ to $20\text{dm}^3$ if amount of work done is -600 J .

Calculate the work done in joule if 2 moles of an ideal gas expand isothermally from \(15.5 \text{ dm}^3\) to \(20 \text{ dm}^3\) at constant pressure 1 atm .