Question
In terms of the calorific value, identify the correct sequence :
The correct answer is
Hydrogen > methane > ethanol > methanol
Calorific Value Sequence Explained
The calorific value represents the amount of heat energy released per unit mass during the complete combustion of a substance.
Substance Calorific Values
Comparing the typical calorific values (on a mass basis) for the given substances:
- Hydrogen ($H_2$): Approximately 142 MJ/kg. This is significantly higher than the others.
- Methane ($CH_4$): Approximately 55.5 MJ/kg. The primary component of natural gas.
- Ethanol ($C_2H_5OH$): Approximately 29.7 MJ/kg. An alcohol fuel.
- Methanol ($CH_3OH$): Approximately 22.7 MJ/kg. Another alcohol fuel, with a lower value than ethanol.
Correct Sequence Determination
Based on these values, the correct sequence from highest calorific value to lowest is:
Hydrogen > Methane > Ethanol > Methanol
This order corresponds to Option B.
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Important Questions from Energy and Environment - Teaching
- Which of the following fuels has the highest HHV carbon intensity ?
- Burning of 1 mol of $\text{CH}_4$ liberates 890 kJ of energy and 1 mol of $\text{CO}_2$. Since 1 mol of $\text{CO}_2$ has 12 g of carbon, the higher heating value (HHV) of methane is :
- The air-to-fuel ratio (A/F) for complete combustion in an internal combustion engine is about :
- Consider solar insolation of $400 \text{ W/m}^2$ incident on a single solar cell of area $100 \text{ cm}^2$. If only $15\%$ of the photons cause electron - hole pairs and the average energy of incident photons is $\sim 1 \text{ eV}$, the short circuit current of the cell is :
- At a given location the wind speeds are predominantly in the range $6$ to $6.4 \text{ m/s}$. This location’s wind power class will be termed as :
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