NEET UG CHEMISTRY MCQ: THERMODYNAMICS

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Analyzing +4 | -1

When 1 mole of

\mathrm{Na}(\mathrm{s})

is dissolved in large volume of water at

298 \mathrm{~K}

and

1 \mathrm{~bar}, 184 \mathrm{~kJ} / \mathrm{mol}

heat is released. When 1 mole of

\mathrm{Na}_2 \mathrm{O}(\mathrm{s})

is dissolved in large volume of water at

298 \mathrm{~K}

and

1 \mathrm{~bar}, 238 \mathrm{~kJ} / \mathrm{mol}

is released. If the enthalpy of formation of water is

-286 \mathrm{~kJ} / \mathrm{mol},

then the enthalpy of formation of sodium oxide is

View answer and explanation

Correct option: C

-416 \mathrm{~kJ} / \mathrm{mol}

Option C (-416 kJ/mol) is correct because the enthalpy of formation of sodium oxide can be calculated using Hess's Law and the given enthalpies of dissolution and formation of water.

More Questions from THERMODYNAMICS

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The internal energy of one mole of a gas is: An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If

{T_i}

is the initial temperature and

{T_f}

is the final temperature, which of the following statements is correct? For which of the process, ∆S is negative? The work done by a weightless piston in causing an expansion ∆V (at constant temperature), when the opposing pressure, P is variable, is given by: Assertion :- At constant pressure of the change

\mathrm{H}_2 \mathrm{O}(\mathrm{s}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{g})

work done is negative.

Reason :- During phase transition work done is always negative. For the reaction,

\mathrm{X}_2 \mathrm{O_4(l}) \longrightarrow 2 \mathrm{XO}_2(\mathrm{g}), \Delta U=2.1 \mathrm{~kcal}, \Delta S=20 \mathrm{~cal} \mathrm{~K}^{-1}

300 \mathrm{~K}

. Hence,

\Delta G