1. Tardigrade
  2. Question
  3. Chemistry
  4. At 25° C , 50 g of iron reacts with HCl to form FeCl2 . The evolved hydrogen gas expands against a constant pressure of 1 bar. The work done by the gas during this expansion is J. (Round off to the Nearest Integer) [Given: R =8.314 J mol -1 K -1 . Assume, hydrogen is an ideal gas] [Atomic mass off Fe is 55.85 u ]

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. At $25^{\circ} C , 50\, g$ of iron reacts with $HCl$ to form $FeCl_{2} .$ The evolved hydrogen gas expands against a constant pressure of $1$ bar. The work done by the gas during this expansion is ________ $J$.
(Round off to the Nearest Integer)
[Given: $R =8.314 \,J\,mol ^{-1} K ^{-1} .$ Assume,
hydrogen is an ideal gas]
[Atomic mass off Fe is $55.85\, u$ ]

JEE MainJEE Main 2021States of Matter

Solution:

$T =298 \,K , R =8.314 \frac{ J }{ mol\,K }$

$\rightarrow$ Chemical reaction is $Fe +2 HCl \rightarrow FeCl _{2}+ H _{2}( g )$

$50\,g P =1$ bar

$=\frac{50}{55.85}\,\,mol$

$\frac{50}{55.85} \,\,mol$

$\rightarrow$ Work done for $1 \,mol$ gas $=- P _{ ext } \times \Delta V$

$=\Delta ng RT$

$=-1 \times 8.314 \times 298 \,J$

$\rightarrow $ Work done for $\frac{50}{55.85}$ mol of gas

$=-1.8314 \times 298 \times \frac{50}{55.85} \,J$

$=-2218.059\,J$

$=-2218 \,J$