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For questions about the combustion of an organic molecule or inorganic substance. Do not use this tag if your question is about the [stoichiometry] of a combustion reaction, or for the calculations of [thermodynamics] functions (like enthalpy change).

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3answers
95 views

Combustion analysis methodology question

I am questioning the answer key of an exam question my chemistry professor has given, because I think there is a flaw in the methodology of the exam answer. I have worked out my solution using my ...
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1answer
27 views

Are there gases that spontaneously combust when mixed with oxygen?

Is there a known gas that would combust by there mere action of mixing with oxygen? So, we could put this hypothetical gas in a balloon, and if the balloon popped, it would combust and explode.
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0answers
14 views

Reaction of FeCl3 to red-hot high carbon steel in an open top container [on hold]

I know when making FeCl3 you produce Hydrogen, so my question is if someone (namely me) were to quench red-hot steel (hi~ish carbon) in FeCl3 would there be a great risk of combustion? I have seen ...
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1answer
34 views

Is flour or baking soda really suitable for extinguishing grease fires?

I think most have heard the advise that you should put flour (or baking soda) on a grease fire to absorb the oil before. While this is certainly better than using water, I'm skeptical. For starters ...
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1answer
40 views
+50

Calorific value of a gas in combustion

The Wikipedia article on heat of combustion says: The calorific value [...] may be expressed with the quantities: energy/mole of fuel energy/mass of fuel energy/volume of the fuel ...
3
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1answer
56 views

How is the light from a fire emitted?

When you see a fire burning, you have wood (fuel) interacting with oxygen which (through a chemical reaction) gives off heat - and light. But the light appears to emit at some point well-away from ...
2
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1answer
76 views

What is the mechanism of alkane combustion?

I understand that combustion of hydrocarbons (such as alkanes) produces energy by breaking bonds: $$\ce{C_nH_{2n} + $\frac{3n}{2}$ O2 -> nCO2 + n H2O}$$ And I can find dozens of explanations of ...
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1answer
44 views

Is sodium “also known to turn purple and combust (like lithium),” when exposed to water?

I understand that indicator solutions can change color depending on pH, but the following statements in the Phys.org article Super cheap earth element to advance new battery tech to the industry has ...
7
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2answers
334 views

Do all flames require the same minimum concentration of oxygen to sustain themsleves?

Assume you have burned some substance A in an airtight container until the fire goes out due to insufficient oxygen. You then place some burning substance B in the container through an airlock. Are ...
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1answer
28 views

Carbon emission in absence of oxygen [closed]

When wood is pyrolysed in absence of air is $\ce{CO2}$ emitted. If yes why is it not combustible?
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1answer
45 views

What substances are hypergolic with liquid O2?

If something flammable is surrounded just by oxygen, I should see flame, right? The object would be even surrounded by more molecules than in the case of gas oxygen. On the youtube I see that people ...
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0answers
34 views

Does the ignition temperature of a substance decrease with the concentration of oxygen?

Is it possible for a substance to undergo combustion at a temperature lower than its ignition point if the concentration of oxygen increases?
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0answers
69 views

Computing the turbulent flame length

There is a problem I found online for practice that I cannot solve: Problem Methane, $\ce{CH4}$, emerges from a $1\ \mathrm{cm}$ diameter nozzle at a rate of $120\ \mathrm{cm^3/s}$ and a mole ...
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0answers
12 views

Calorific values of biodiesels synthesized from vegetable oils

Calorific values of biodiesels vary depending on the feedstock used in synthesizing it. Although it's not by a lot, is there a particular reason for this? I suspect it's something to do with the ...
3
votes
1answer
126 views

Why do highly branched alkanes have higher octane numbers than their corresponding linear isomer?

The octane number of fuels are based on a set of primary reference fuels, which are mixtures of iso-octane and n-heptane. Now iso-octane being branched alkane has very less tendency to react and given ...
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0answers
31 views

Why fire spreads out, depending on burning substance, with different speed?

In Action movies, I have seen a couple of times that if flammable gases or liquids like benzene are ignited, the fire spreads out within fraction of a second and sometimes there is also an explosion. ...
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0answers
23 views

Is there the chemical component Hydrogen in Fire of any kind? [duplicate]

I know this sounds like a dumb question but I am wondering about the chemical composition of Fire, and it seems rather strange to me for the most part, is one of the compositions hydrogen since it ...
-1
votes
1answer
67 views

Why are lower alcohols less flammable than their corresponding alkanes?

How to compare the general trend in amount of combustion in lower alcohols? (upto five/six carbons) Does the branching or straight chain have any effect on combustion?
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1answer
50 views

Heat of Combustion

Methanol ($\ce{CH3OH}$) is regarded by many chemists as a possible liquid fuel for the future. The combustion of methanol occurs according to the equation: $$\ce{2CH3OH(g) + 3O2(g) -> 2CO2(g) +...
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1answer
26 views

Molar Heat of combustion with different fuels

I'm not sure exactly how to attack this question, I'm sure that you have to use equations such as $$Q=mc\triangle T$$ $$n=\frac{MM}{m}$$ But I don't know where to use them. Any help would be ...
1
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1answer
35 views

Why doesn't this question violate the conservation of mass?

Combustion of of $0.255 \space g$ of isopropyl alcohol produces $0.561 \space g$ of $\ce{CO_2}$ and $0.306 \space g$ of $\ce{H_2O}$. Determine the emperical formula of isopropyl alcohol. I'm not ...
7
votes
1answer
87 views

Why doesn't the carbon dioxide produced by a fire put out said fire?

Carbon dioxide ($\ce{CO2}$) is used in some fire extinguishers to put out fire, but a combustion reaction itself produces $\ce{CO2}$. Why do we get fire then? $$\ce{CH4 + O2 -> CO2 + H2O}$$ Why ...
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1answer
39 views

More effective fire extinguisher liquid than water

I join robot fire fighting contest. One of the mission is to extinguish candle by spraying it with liquid (water is default option). For spray mechanism I use pump with Venturi effect principle. Is ...
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1answer
36 views

Polluting agents generated by road traffic in a city [closed]

I want to measure the air quality according to road traffic in a city. What are the polluting agents (generated by fuel combustion) strictly related and generated by road vehicles that is worth ...
1
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1answer
89 views

Can glucose burn in chlorine?

Chlorine is an oxidizing agent, so could it replace oxygen? If so, what would be the products, and how much energy would such reactions release? Do any other carbohydrates burn in chlorine? I cannot ...
4
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1answer
257 views

Colored Flames Experiment

I am going to be doing a gender reveal for my sister's pregnancy. To do this, we wanted to light a huge fire pit and throw in a chemical to change the fire into the color (red/pink for girl, blue/...
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0answers
15 views

PM2.5 - result of compression ignition or Diesel fuel?

When reading about PM2.5 particles, one can see that one of the sources for such particulates is the Diesel engine. I was wondering if it is the Diesel fuel itself or is is the ignition type (i.e. ...
0
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1answer
23 views

Can the pyrophoric tendencies of a pyrophoric substance be suppressed in a pressurized environment?

It's common knowledge that the pressure of an environment influences many properties of a substance, like the melting point, boiling point, or triple point. Pyrophoric substances ignite spontaneously ...
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1answer
48 views

Combustion at 298K

Question: (source IITJEE 1992) An aliphatic thiol undergoes combustion at 298K to give carbon dioxide, water and sulfur dioxide. What are the physical states of the products?(solid/liquid/gas) I ...
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1answer
81 views

How can we separate carbon monoxide from wood gas?

I am thinking about using open source wiki designs from allpowerlabs to construct a wood gas generator. The motivation came from experiencing a 10 day power outage after super storm Sandy. The ...
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0answers
199 views

Reaction rate constants for methane combustion

I can't find a rate constant or activation energy for the methane combustion reaction given by: $$\ce{ CH4 + 2O2 -> CO2 + 2H2O}$$ Do all reactions have a rate constant? The NIST web site lists ...
9
votes
1answer
725 views

What chemical can cause such a fire? [closed]

A friend of mine who thinks that she is under influence of black magic met an astrologer. The astrologer asked her to wear a t-shirt for three nights and then bring that to him. The astrologer then ...
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1answer
63 views

Can oxidation of hydrogen happen in room temperature? [duplicate]

Here is my explanation about the reaction between hydrogen or methane and oxygen. Hydrogen molecules and oxygen molecules can collide sucessfully and react if they have enough energy. In room ...
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1answer
19 views

How do you work out the amount of energy which will be released when a substance undergoes combustion in a pure oxygen environment [closed]

For instance, if we have an abundance of pure Oxygen and one kilogram of Hydrogen and all the Hydrogen reacts with the Oxygen to form H20, how do you work out the amount of energy which will be ...
4
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2answers
78 views

Can carbon monoxide from a floor-heater in a poorly ventilated room eventually be ignited by the fire and explode?

I have often wondered about carbon monoxide accidents caused by free-standing heaters burning in a poorly ventilated room causing fatalities. I am aware that CO is explosive between 12 and 75% volume ...
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0answers
229 views

Determining enthalpy of combustion of a mixture

I am designing an experiment to see how the enthalpy of combustion changes when you mix different ratios of substances together (e.g. methanol and ethanol in 1:1 , or 1:2, or 1:3 rations etc). I was ...
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2answers
145 views

Carbon tetraradical

I was just reading through Reactions: The private life of atoms by Peter Atkins and I noticed that in Chapter 3, the chapter on the combustion reaction, the author writes: As we watch we see $\ce {...
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4answers
1k views

Would the concentration of oxygen around fire increase as we get close to the fire (from the outside)

Since fire require oxygen, wouldn't a fire, like those in the American forest along west coast, constantly draws in oxygen from around? And if that is so, would the concentration of oxygen around the ...
3
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0answers
77 views

Calculate work done by burning benzoic acid exposed to the free air

I'm self-studying and can't solve this problem in Ball's Physical Chemistry. Now, the errata shows that the answer in the book is not correct; still, I can not make sense of it. $(2.55)$ Benzoic ...
4
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2answers
54 views

Are all highly shock sensitive chemicals highly temperature sensitive too?

I found that some highly shock sensitive explosives like lead azide, mercury fulminate have a relatively high auto-ignition temperature. I want to know if it's a general property or not and why so? ...
0
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1answer
359 views

Why are some materials more flammable than others? [closed]

Wood and oil are flammable materials, but water isn't. Moreover, flames spread a lot faster in oil than in a piece of paper. What is the reason that it is so? I also don't know why a small flame can ...
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1answer
128 views

Propane-water molar ratio [closed]

Propane gas, $\ce{C3H8}$, burns in oxygen to produce carbon dioxide and water vapour as follows: $$\ce{C3H8 (g) + 5O2 (g) = 3 CO2(g) + 4 H2O (g) + \pu{2200 kJ}}$$ If $\pu{1.5 mol}$ of ...
2
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0answers
34 views

Magnesium combustion heat [closed]

When you are going to burn magnesium you need to wait a few seconds before it actually starts to burn. To get to this point it needs a certain amount of energy/heat. How much does it need?
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1answer
49 views

How can pressure build up in an equimolar gaseous reaction? [closed]

To make the question concrete, if you conduct a reaction like $\ce{H2 + Cl2 -> 2HCl}$ in a stoppered test tube, the stopper will aggressively pop off (or the glass will shatter) despite the fact ...
5
votes
0answers
102 views

What is wrong with my enthalpy calculations?

I need to calculate the enthalpy of combustion for butane using bond formation energies. Thus I first balance the equation: $$\ce{C4H10 + 6.5 O2 -> 4 CO2 + 5 H2O}$$ Then, I calculate the total ...
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0answers
35 views

Can I approximate the CO concentration of a combustion product, if I know the CO2 and O2 concentration?

Assume I have the product (exhaust gas) from a combusted air/petrol mix. The mixing ratio was richer than stoichiometric (i.e., air:fuel < 14.67 in this case), so there was no excess of oxygen. I ...
5
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0answers
47 views

Why old gasoline has more “kick”?

Gasoline isn't something that we store in jerry cans in everyday life, right? We normally have it in our car's tank. But when you have a grass cutter machine or lawn mower that runs on gas, you store ...
4
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0answers
87 views

Which (carbonaceous) fuels produce more or less soot in a diffusion flame, and how to predict that?

From what I've read, the production of soot in a flame is still an open research topic. But some hydrocarbon fuels produce much more soot than others. Are there (simple) rules that tell which fuels ...
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1answer
145 views

Oxygen required to burn carbon [closed]

What volume of oxygen at standard temperature and pressure (STP) is required to burn $2.4 \,\rm{g}$ of carbon to completion?
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0answers
106 views

Is brass combustible in high pressure oxygen environment?

Some metals are particularly ignitable in high pressure oxygen environments, like stainless steel and aluminum. Copper and nickel, on the other hand will self-extinguish when ignited. Does anyone know ...