1. Tardigrade
  2. Question
  3. Chemistry
  4. For complete combustion of methanol CH 3 OH (1)+(3/2) O 2( g ) arrow CO 2( g )+2 H 2 O (1) the amount of heat produced as measured by bomb calorimeter is 726 kJ mol -1 at 27° C. The enthalpy of combustion for the reaction is - x kJ mol -1, where x is . (Nearest integer) (Given: R =8.3 JK -1 mol -1 )

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Q. For complete combustion of methanol
$CH _{3} OH (1)+\frac{3}{2} O _{2}( g ) \rightarrow CO _{2}( g )+2 H _{2} O (1)$
the amount of heat produced as measured by bomb calorimeter is $726 \,kJ\, mol ^{-1}$ at $27^{\circ} C$. The enthalpy of combustion for the reaction is $- x \,kJ\, mol ^{-1}$, where $x$ is ________. (Nearest integer)
(Given : $R =8.3 \,JK ^{-1}\, mol ^{-1}$ )

JEE MainJEE Main 2022Thermodynamics

Solution:

$\Delta U =-726 \,KJ / mol$
$\Delta ng =1-3 / 2=\frac{-1}{2}$
$\Delta H =\Delta U +\Delta ngRT$
$=-726-\frac{1}{2} \times \frac{8.3 \times 300}{1000}$
$=-727.245$