Combustion of gas

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Combustion of gas

Postby 205389184 » Thu Mar 05, 2020 9:41 am

Will the combustion of gas always be spontaneous?

Sebastian Lee 1L
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Re: Combustion of gas

Postby Sebastian Lee 1L » Thu Mar 05, 2020 12:09 pm

Under standard conditions, the combustion of gas is most likely spontaneous since you would usually be releasing heat (-delta H) and increasing entropy (+delta S). However, I wouldn't say that combustion is always spontaneous, especially depending on non-standard conditions. For example, if you have a very high Q value (many products vs. little reactants), the delta G may be positive (not spontaneous).

BritneyP- 2c
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Re: Combustion of gas

Postby BritneyP- 2c » Thu Mar 05, 2020 12:32 pm

It should be spontaneous most of the time because you are releasing heat, and gas has more disorder to it. But i wouldn't say it is spontaneous all the time.

Cooper Baddley 1F
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Re: Combustion of gas

Postby Cooper Baddley 1F » Thu Mar 05, 2020 3:41 pm

Hard to say something is always spontaneous but most of the time it will be

kendal mccarthy
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Re: Combustion of gas

Postby kendal mccarthy » Sun Mar 08, 2020 11:31 pm

I think most combustion reactions are spontaneous because they are exothermic, releasing heat, and usually cause an increase in gaseous substances, which have a higher value for entropy. It really depends on other determining factors, however.

Rohit Ghosh 4F
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Re: Combustion of gas

Postby Rohit Ghosh 4F » Wed Mar 11, 2020 11:42 am

The way you can be completely sure that the reaction is spontaneous is by looking at the equation: G = H - TS. Because H will most likely be negative and S will be positive, combustion usually is spontaneous.

ValerieChavarin 4F
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Re: Combustion of gas

Postby ValerieChavarin 4F » Thu Mar 12, 2020 7:22 am

In the case of ∆G° = ∆H° - T∆S°, which indicates standard condition yes. The combustion of gas will be spontaneous due to the negative enthalpy value, the release of heat through an exothermic reaction, and a positive (increasing) entropy.

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