Tag: study of enthalpy

Questions Related to study of enthalpy

Gross & net calorific value is the same for ___________.

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

  1. blast furnace gas

  2. coke oven gas

  3. L.D. converter gas

  4. none of these

Show answer
Correct Option: C
Explanation:

Gross & net calorific value is the same for L.D converter gas. Calorific value is the total quantity of heat liberated by the complete combustion of a unit mass of the fuel in air or oxygen. It is expressed in $kcal/m^3$ or British thermal unit (B.T.U) per cubic foot.

Which of the following has the highest calorific value?

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

  1. Coal gas

  2. Water gas

  3. Producer gas

  4. Carbon dixode gas

Show answer
Correct Option: A
Explanation:

Calorific value: The amount of energy produced by the complete combustion of a material or fuel.
Coal gas $H _2+CO+CH _4$ has the highest calorific value.

Calorific value is expressed in:

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

  1. calories per gram

  2. kilojoules per gram

  3. kilocalories per gram

  4. calories per kilogram

Show answer
Correct Option: C
Explanation:

The calorific value of a fuel is the quantity of heat produced by its combustion, at constant pressure and under STP conditions. It is mainly expressed in kcal/g.

Which of the following has the highest calorific value?

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

  1. Petrol

  2. Coke

  3. Natural gas

  4. Kerosene

Show answer
Correct Option: A
Explanation:

Petrol has highest calorifc value among all.
Petrol-48,000kJ/kg
Coke-31,000kJ/kg
Natural gas-43,000kJ/kg
Kerosene-46,200kJ/kg

 Which fuel is used for running automobiles?

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

  1. Wood

  2. Charcoal

  3. Petrol

  4. Kerocene

Show answer
Correct Option: C
Explanation:

Petrol is the combustible fuel with high calorific value which is used for the running automobiles like car, motorcycles etc.


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

Which among the following is the best fuel?

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

  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

Show answer
Correct Option: D
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.

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

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

  1. heat capacity

  2. calorific value

  3. vapour density

  4. boiling point

Show answer
Correct Option: B
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 $\text{B}$

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.

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

  1. 10,000 J/day

  2. 15,000 J/day

  3. 20,000 J/day

  4. 25,000 J/day

Show answer
Correct Option: C
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.

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

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

  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

Show answer
Correct Option: C
Explanation:

Natural gas         $ = 43000 kJ/kg$

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

Which of the following has the lowest calorific value?

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

  1. $C _2H _6$

  2. $C _2H _5OH$

  3. $C _2H _4$

  4. $H _2$

Show answer
Correct Option: D
Explanation:

The calorific value is defined as the amount of heat released during complete combustion of a substance with oxygen under standard condition.

H$ _2$ has the lowest calorific value.