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Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

Which among the following is the best fuel?

  1. Wood with calorific value 4000 Cal/g

  2. Coke with calorific value 8000 Cal/g

  3. Coal with calorific value 7000 Cal/g

  4. Kerosene with calorific value 11,200 Cal/g
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Higher the heating value or higher the calorific value better the fuel is, so kerosene has a higher heating value which is measured by bomb calorimeter.

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

The heat produced by burning 1 g of fuel completely is known as _____________.

  1. heat capacity

  2. calorific value

  3. vapour density

  4. boiling point
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 Calorific value is the quantity of heat produced by the complete combustion of a given mass of a fuel, usually expressed in joules per kilogram. It can be defined as the amount of heat energy produced on complete combustion of 1 Kg of fuel.


Hence, the correct option is $\text{B}$

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

A family consumes 12 kg of LPG in 30 days. Calculate the average energy consumed per day if the calorific value of LPG is 50 kJ/kg.

  1. 10,000 J/day

  2. 15,000 J/day

  3. 20,000 J/day

  4. 25,000 J/day
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Energy released by 12 kg of LPG =  12 %$\times$ 50 kJ $= $ 600 kJ
$\therefore$ energy consumed per day
$\displaystyle \frac {600\,kJ}{30}\, =\, 20,000$ Joules/day.

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

The calorific values of wood, bituminous coal, natural gas and charcoal vary in the order:

  1. wood > bituminous > natural gas > charcoal

  2. wood > bituminous coal > charcoal > natural gas

  3. natural gas > charcoal > bituminous coal > wood

  4. natural gas> bituminous coal> wood> charcoal
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Natural gas         $ = 43000 kJ/kg$

Charcoal             $ = 29600 kJ/kg$
Bituminous coal $ = 23250 kJ/kg$
Wood                   $  =  17400 kJ/kg$

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

Which one of the following has the highest calorific value?

  1. Kerosene

  2. Biogas

  3. LPG

  4. Petrol
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The calorific value of a fuel is the quantity of heat produced by its combustion - at constant pressure and under a conditions known as " normal " of temperature and pressure (i.e. to 0oC and under a pressure of 1,013 mbar). 
The combustion of a fuel product generates water vapor. Certain techniques are used to recover the quantity of heat contained in this water vapor by condensing it. 
The Higher Calorific Value (or Gross Calorific Value - GCV) supposes that the water of combustion is entirely condensed and that the heat contained in the water vapor is recovered. 
The Lower Calorific Value (or Net Calorific Value - NCV) supposes that the products of combustion contains the water vapor. The heat contained in the water vapor is not recovered. 
LPG has a typical specific calorific value of 46.1 MJ/kg.
Calorific value of Bio gas is about 19 to 25 MJ/cubic meter, depending on the methane percentage in the biogas mix.
Heat of combustion of kerosene for lower heating value is 43.1 MJ/kg, and for higher heating value is 46.2 MJ/kg.
Petrol, calorific value of which is 45.8 MJ/kg.
Thus, LPG has highest calorific value among above.