Tough Engineering Chemistry Questions and Answers focuses on “Determination of Calorific Value of Gaseous and Volatile Liquid Fuels”.
1. Apart from Boy’s calorimeter, which process can be used for finding the calorific value of gases?
a) Bomb calorimeter
b) Heat balance calorimeter
c) Junker’s calorimeter
d) Heat flow calorimeter
Answer: c
Clarification: In this calorimeter, a known volume of gas is burned and imparting heat with maximum efficiency so as to find out the rise in temperature of the water.
2. How many burners are used in Boy’s calorimeter for finding the calorific value for gases and volatile liquid?
a) 4
b) 3
c) 1
d) 2
Answer: d
Clarification: The two flat flame burners are situated in chimney in the calorimeter. Two are used to impart efficient heat to find the rise in temperature.
3. The water condensed from the products of combustion is collected and settles in the Boy’s bomb itself.
a) True
b) False
Answer: b
Clarification: The water condensed from the products of combustion is removed through the side tube, so that its volume can be measured.
4. What is the use of insulating baffles in Boy’s thermometer?
a) To deflect the gas upwards so that it can pass through the holes of the calorimeter
b) To make the gas stable in copper tube
c) To decrease the rate of heating
d) To decrease the temperature of cold water which is obtained from inlet
Answer: a
Clarification: The cold water is sent from the water inlet and the gas is in a chimney which is deflected downwards, for the mixing of gases with water the gases deflected upwards.
5. What is the basic formula for calculating GCV in Boy’s calorimeter?
a) GCV = w(t2+t1)/V
b) GCV = w(t2-t1)/V
c) GCV = V(t2+t1)/w
d) GCV = V(t2-t1)/w
Answer: b
Clarification: In this (t2-t1) is the rise in temperature of the water which is multiplied to its weight and divide by the volume of gas burned at standard conditions of temperature and pressure. Its unit is in cal/m3.
6. What is the main source of error in conducting the experiment of Boy’s calorimeter?
a) The temperature of gas is greater than the room temperature
b) Due to presence of moisture
c) The mass of the gas is comparatively low
d) Due to the rise in ambient temperature
Answer: d
Clarification: Ambient temperature is the temperature of the air in the room. If this temperature changes suddenly, it will affect the readings of the experiment.
7. What is the basic formula for calculating NCV in Boy’s Calorimeter?
a) NCV = GCV – (m/V)×587
b) NCV = GCV – (V/m)×587
c) NCV = GCV + (m/V)×587
d) NCV = GCV + (V/m)×587
Answer: a
Clarification: Since the calorific value of gases in expressed on volumetric bases, it is essential to define conditions of temperature and pressure. Its unit is same as GCV which is cal/m3.
8. Determine the gross calorific value (GCV) of a gas, having following results after using Boy’s calorimeter: Volume of the gaseous fuel burnt = 0.093 m3, weight of the water used for cooling = 30.5 kg, Weight of the steam condensed = 31 gm, Temperature of inlet water = 26.1 0C and Temperature of outlet water = 36.5 0C?
a) 3100 Kcal/m3
b) 3310 cal/gm
c) 3410 Kcal/m3
d) 3780 Kcal/gm
Answer: c
Clarification: By using relation GCV = w(t2 – t1)/ V,
We get GCV = 3410 Kcal/m3.
9. Determine net calorific value of a volatile liquid fuel, having following results after using Boy’s calorimeter: Volume of the liquid fuel burnt = 0.152 m3, weight of the water used for cooling = 48.5 kg, Weight of the steam condensed = 91 gm, Temperature of inlet water = 35.2 0C and Temperature of outlet water = 42.6 0C?
a) 2361.184 Kcal/m3
b) 2013.348 Kcal/m3
c) 2256.95 Kcal/m3
d) 2185.679 Kcal/m3
Answer: b
Clarification: By using relation GCV = w(t2 – t1)/ V,
We get GCV = 2361.184 Kcal/m3
NCV = GCV – (m/V)×587
NCV = 2013.348 Kcal/m3.
10. Junker’s calorimeter cannot be used for measuring the calorific value of volatile liquid fuel.
a) True
b) False
Answer: a
Clarification: Junker’s calorimeter can be used for measuring the calorific value of both gaseous and volatile liquid fuel. Also Boy’s calorimeter is used for measuring the calorific values of both gaseous and volatile liquid fuel. For solids and non-volatile liquid fuel Bomb calorimeter is used.
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