Embibe Experts Solutions for Chapter: Thermodynamics, Exercise 3: EXERCISE-3

One mole of solid $\mathrm{Zn}$ is placed in excess of dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$ at $27°\mathrm{C}$ in a cylinder fitted with a piston. Find the value of $∆\mathrm{E}\left(\mathrm{in} \mathrm{kJ}\right)$ for the process if the area of piston is $500{\mathrm{cm}}^2$ and it moves out by $50\mathrm{cm}$ against a pressure of $1\mathrm{atm}$ during the reaction. The heat given to surrounding is $36.5\mathrm{kJ}$.

$\mathrm{Zn}\left(\mathrm{s}\right)+2{\mathrm{H}}^{+}\left(\mathrm{aq}\right)\rightleftharpoons {\mathrm{Zn}}^{2+}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

Give answer in 2 decimal places.

$1 \mathrm{mole}$ of ${\mathrm{CO}}_2$ gas at $300\mathrm{K}$ is expanded under reversible adiabatic condition such that its volume becomes $27$ times.

What is the final temperature in Kelvin?

A sample of a fluorocarbon was allowed to expand reversibly and adiabatically to twice its volume. In the expansion the temperature dropped from $298.15$ to $248.44\mathrm{K}$. Assume the gas behaves perfectly. Estimate the value of ${\mathrm{C}}_{\mathrm{v}.\mathrm{m}}$. $\left(\mathrm{in} {\mathrm{JK}}^{-1} {\mathrm{mol}}^{-1}\right)$, Give answer in 2 decimal places.

Find the work done (in $\mathrm{kJ}$) when one mole of the gas is expanded reversibly and isothermally from $5\mathrm{atm}$ to $1\mathrm{atm}$ at $25°\mathrm{C}$?

The standard enthalpy of formation of water liquid is $-285.76\mathrm{kJ}$ at $298\mathrm{K}$. Calculate the value of enthalpy change (in $\mathrm{kJ}$) at $373\mathrm{K}$. The molar heat capacities at constant pressure $\left({\mathrm{C}}_{\mathrm{P}}\right)$ in the given temperature range of ${\mathrm{H}}_2\left(\mathrm{g}\right),{\mathrm{O}}_2\left(\mathrm{g}\right)$ and ${\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$ are respectively $38.83, 29.16$ and $75.312 {\mathrm{JK}}^{-1} {\mathrm{mol}}^{-1}$.

Methane (Considered to be an ideal gas) initially at $25°\mathrm{C}$ and $1$ bar pressure is heated at constant pressure until the volume has doubled. The variation of the molar heat capacity with absolute temperature is given by:

${\mathrm{C}}_{\mathrm{P}}=22.34+48.1\times {10}^{-3}\mathrm{T}$. where ${\mathrm{C}}_{\mathrm{P}}$ is in ${\mathrm{JK}}^{-1} {\mathrm{mol}}^{-1}$. Calculate $∆\mathrm{U}$ in $\mathrm{kJ}$.

One mole of $\mathrm{NaCl}\left(\mathrm{s}\right)$ on melting absorbed $30.5\mathrm{kJ}$ of heat and its entropy is increased by $28.8{\mathrm{JK}}^{-1}$. What is the melting point of sodium chloride (in Kelvin)?

Oxygen is heated from $300\mathrm{K}$ to $600\mathrm{K}$ at a constant pressure of $1 \mathrm{bar}$. The molar heat capacity in ${\mathrm{JK}}^{-1} {\mathrm{mol}}^{-1}$ for ${\mathrm{O}}_2$ is:

${\mathrm{C}}_{\mathrm{P}}=25.5+13.6\times {10}^{-3}\mathrm{T}-42.5\times {10}^{-7}{\mathrm{T}}^2$

What is the increases in molar entropy (in Joule)?