CH3OH(ℓ)+23O2( g)→CO2( g)+2H2O(ℓ)ΔH=−726 kJ mol−1 Also ΔGf0CH3OH(ℓ)=−166.2 kJ mol−1 ΔGf0H2O(ℓ)=−237.2 kJ mol−1ΔGf0CO2(ℓ)=−394.4 kJ mol−1∵ΔG=ΣΔGf0 products −ΣΔGf0 reactants. =−394.4−2(237.2)+166.2=−702.6 kJ mol−1 now Efficiency of fuel cell =ΔHΔG×100=726702.6×100=97%
In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is CH_3 OH(ell)+ 3 2 O_2( ~g) → CO_2( ~g)+2 H_2 O(ell) At…
JEE Main 2009 — Chemistry Physical Chemistry
2009mcqhard
In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is CH3OH(ℓ)+23O2( g)→CO2( g)+2H2O(ℓ) At 298 K standard Gibb's energies of formation for CH3OH(ℓ),H2O(ℓ) and CO2( g) are −166.2,−237.2 and −394.4 kJ mol−1 respectively. If standard enthalpy of combustion of methanol is −726 kJ mol−1, efficiency of the fuel cell will be
Official previous-year question
Held on 30 Apr 2009 · Verified 6 Jul 2026.
Options
- A
80%
- B
87%
- C
90%
- D
97%
Did you get this right?
Sign in to track your attempts and accuracy.
Your note
Sign in to keep a private note on this question. Nothing you write is ever public.
JEE Main Physical Chemistry in other years
More JEE Main Physical Chemistry questions
What is the ratio of wave number of first line (lowest energy line) of Balmer series of H atomic spectrum to first line of its Brackett series?
2026medium
  Which of the following point in Figure 2 most accurately represents the nodal surface as shown in Figure 1?
2026medium
At 298 K, the mole percentage of $\mathrm{N}_{2}(\mathrm{~g})$ in air is $80 \%$. Water is in equilibrium with air at a pressure of 10 atm. What is the mole fraction of $\mathrm{N}_{2}(\mathrm{~g})$ in water at 298 K ? ($\mathrm{K}_{\mathrm{H}}$ for $\mathrm{N}_{2}$ is $6.5 \times 10^{7} \mathrm{~mm} \mathrm{Hg}$)
2026medium
Electricity is passed through an acidic solution of $\mathrm{Cu}^{2+}$ till all the $\mathrm{Cu}^{2+}$ was exhausted, leading to the deposition of 300 mg of Cu metal. However, a current of 600 mA was continued to pass through the same solution for another 28 minutes by keeping the total volume of the solution fixed at 200 mL. The total volume of oxygen evolved at STP during the entire process is $\_\_\_\_$ mL. (Nearest integer) [Given: $\mathrm{Cu}^{2+}(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow \mathrm{Cu}(\mathrm{s}) \mathrm{E}_{\text {red }}^{\mathrm{o}}=+0.34 \mathrm{~V}$ $\mathrm{O}_{2}(\mathrm{~g})+4 \mathrm{H}^{+}+4 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_{2} \mathrm{O} \mathrm{E}_{\text {red }}^{\mathrm{o}}=+1.23 \mathrm{~V}$ Molar mass of $\mathrm{Cu}=63.54 \mathrm{~g} \mathrm{~mol}^{-1}$ Molar mass of $\mathrm{O}_{2}=32 \mathrm{~g} \mathrm{~mol}^{-1}$ Faraday Constant $=96500 \mathrm{C} \mathrm{mol}^{-1}$ Molar volume at $\mathrm{STP}=22.4 \mathrm{~L}$]
2026hard
Arrange the following resultant mixtures in increasing order of their pH values A. $10$ mL $0.2$ M Ca(OH)$_2$ + $25$ mL $0.1$ M HCl B. $10$ mL $0.01$ M H$_2$SO$_4$ + $10$ mL $0.01$ M Ca(OH)$_2$ C. $10$ mL $0.1$ M H$_2$SO$_4$ + $10$ mL $0.1$ M KOH Choose the correct answer from the options given below:
2026medium
Other Chemistry topics for JEE Main
Keep practicing Physical Chemistry
Work through every JEE Main Physical Chemistry PYQ, year by year.