Chemical Engineering - Chemical Engineering Basics - Discussion

Discussion Forum : Chemical Engineering Basics - Section 1 (Q.No. 1)
1.
Which one of the following is incombustible ?
H2
CCl4
C2H2
S
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
47 comments Page 1 of 5.

ANVESH said:   8 years ago
Consider the combustion of a simple molecule methane CH4:

CH4 + 2O2 = CO2 + 2H2O.

However, if we consider a similar molecule CCl4, carbon tetrachloride, which is just a replacement of H by Cl in methane, is incombustible.

This can be explained by observing the reaction above. CH4 burns to give CO2 and Water. Hydrogen being an electropositive element joins oxygen quickly.

However, chlorine being an electronegative element would like to connect to an electropositive element carbon, as it can pull the electron pair closer to itself!

Getting Cl in +1 state is difficult.

So the reaction
CCl4 + 2O2 = CO2 + 2Cl2O is least probable.

Because it doesn't combust, it was used as a fire extinguisher under the name pyrene.
(5)

Zoya khan said:   1 year ago
Among the options given, the incombustible substance is CCl4 (carbon tetrachloride).

Here’s why;

-> H2 (hydrogen gas) is highly combustible and burns with a pale blue, almost invisible flame.

-> C2H2 (acetylene) is also highly combustible and is often used as a fuel in welding torches.

-> S (sulfur) is combustible and burns with a blue flame, producing sulfur dioxide.

-> CCl4 (carbon tetrachloride), on the other hand, does not support combustion and is used as a fire extinguishing agent and in other applications where non-flammability is required.
(16)

Zoya khan said:   1 year ago
Among the options given, the incombustible substance is CCl4 (carbon tetrachloride).

Here’s why;

-> H2 (hydrogen gas) is highly combustible and burns with a pale blue, almost invisible flame.

-> C2H2 (acetylene) is also highly combustible and is often used as a fuel in welding torches.

-> S (sulfur) is combustible and burns with a blue flame, producing sulfur dioxide.

-> CCl4 (carbon tetrachloride), on the other hand, does not support combustion and is used as a fire extinguishing agent and in other applications where non-flammability is required.
(4)

Zoya khan said:   1 year ago
Among the options given, the incombustible substance is CCl4 (carbon tetrachloride).

Here’s why;

-> H2 (hydrogen gas) is highly combustible and burns with a pale blue, almost invisible flame.

-> C2H2 (acetylene) is also highly combustible and is often used as a fuel in welding torches.

-> S (sulfur) is combustible and burns with a blue flame, producing sulfur dioxide.

-> CCl4 (carbon tetrachloride), on the other hand, does not support combustion and is used as a fire extinguishing agent and in other applications where non-flammability is required.

Zoya khan said:   1 year ago
Among the options given, the incombustible substance is CCl4 (carbon tetrachloride).

Here’s why;

-> H2 (hydrogen gas) is highly combustible and burns with a pale blue, almost invisible flame.

-> C2H2 (acetylene) is also highly combustible and is often used as a fuel in welding torches.

-> S (sulfur) is combustible and burns with a blue flame, producing sulfur dioxide.

-> CCl4 (carbon tetrachloride), on the other hand, does not support combustion and is used as a fire extinguishing agent and in other applications where non-flammability is required.

Zoya khan said:   1 year ago
Among the options given, the incombustible substance is CCl4 (carbon tetrachloride).

Here’s why;

-> H2 (hydrogen gas) is highly combustible and burns with a pale blue, almost invisible flame.

-> C2H2 (acetylene) is also highly combustible and is often used as a fuel in welding torches.

-> S (sulfur) is combustible and burns with a blue flame, producing sulfur dioxide.

-> CCl4 (carbon tetrachloride), on the other hand, does not support combustion and is used as a fire extinguishing agent and in other applications where non-flammability is required.

Somdev Ghosh said:   1 decade ago
Combustion means reaction with oxygen or burning in layman's term.

Hypothetically, for combustion of CCl4 , the following reaction would have occurred :

CCl4 + O2 -> CO2 + 2 Cl2

For feasibility of any reaction, the sum of bond energy of all the products should be less than sum of bond energy of all the reactants.

In this case, breaking of O-O, and four C-Cl bonds require more energy than forming two C-O and two Cl-Cl bonds. Hence, CCl4 does not react with Oxygen and is incombustible
(1)

Whajah Bernard said:   6 years ago
CCl4 is incombustible because the combustion products will have higher energy content than that of the reactants. For combustion to take place, the products should contain stable compounds (lower energy content) eg. H2O, CO2 etc. Than that of the reactants. CCl4 is very stable due to its structure.
(2)

Kingsuk Das said:   1 decade ago
The structure of CCl4 is tetrahedral which is geometrically stable and other such as C2H2 has unsaturation moreover S has lone pair electrons in its hybrid d orbitals and H2 also has 1s bonding which the combustible heat energy is evident to break the relevant bond energy in comparison to CCl4

Panchanan panda said:   8 years ago
Carbon tetrachloride has a high degree of liver toxicity, so it is banned in consumer products in the United States. Historically, it was used as a refrigerant, a fire suppression agent, and a cleaning solvent like Carbon Tetrachloride, it saw use as a refrigerant and cleaning solvent.


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