Questions tagged [combustion]

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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14
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2answers
49k views

Heats of combustion and stability of rings

Which isomer would have the largest heat of combustion? A) Propylcyclopropane B) Ethylcyclobutane C) Methylcyclopentane D) Cyclohexane E) Since they are all isomers, all would have the same heat of ...
27
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2answers
4k views

Why do the alkali metals form different products upon combustion in air?

From Wikipedia's article on sodium: When burned in dry air, it forms primarily sodium peroxide with some sodium oxide. We know that sodium has a strong reducing capacity, so why does it produce a ...
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4answers
2k views

Is oxygen necessary for burning?

Is oxygen really necessary for burning things? What if there was no oxygen around? Would there still be a way to burn things?
6
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5answers
3k views

Deciding the order of heat of combustion of isomeric alkanes

I'm asked which one of the alkane has the lowest heat of combustion (note: the question says heat, not enthalpy) and according to the answers, the right one is d. I'm trying to understand why d ...
8
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4answers
2k views

Can paper burn without oxygen or air?

If you put a paper inside an oven vacuum packed and go beyond $250~\mathrm{^\circ C}$, will it burn? There's no oxidizer. If not, what will happen?
14
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5answers
18k views

Can flames be colored black?

Most of us here would know that flames can be colored by adding an appropriate salt to the 'fuel' or by simply introducing it into a flame. Boron and Barium salts give the flame a green tinge, ...
5
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1answer
3k views

Why does a wood fire create benzene?

According to this article called The Fireplace Delusion a wood-fire will create benzene. This surprised me and I can't find an article online that explains the chemical reaction behind that.
3
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1answer
2k 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 ...
140
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7answers
44k views

Why doesn't water burn?

Hydrogen is flammable, and for any fire to burn it needs oxygen. Why does a compound made of hydrogen and oxygen put out fires instead of catalyzing them? I understand that hydrogen and water are ...
10
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1answer
340 views

Gases produced by pyrolysis of cellulose

I heated cotton in a sealed container (with a small hole) over a natural gas flame. Some gases and smoke were produced. What would they probably be? I can come up with some guesses based on the ...
9
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3answers
19k views

Can you melt wood?

We talked about it in our chemistry class but we couldn't get to a conclusion, any help?
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3answers
439 views

Can oxygen burn in hydrogen?

Most combustion happens involves the fuels burning in an oxidant. But there seems to be no reason that it cannot happen in the opposite way. Are there any experiments on oxygen burning in hydrogen? Or ...
62
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1answer
8k views

Why does shaking a match put the fire out?

Move a match slowly and nothing happens but if you shake it violently the fire will extinguish. Oxygen makes fire grow so why does waving a flame through the oxygen rich air put the fire out? Does ...
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3answers
404 views

Open flame combustion in bizarro world

Humans typically achieve combustion by starting a chemical reaction of a fuel (often a carbon $\ce{C}$ containing fluid like methane $\ce{CH4}$), which is is brought into an an oxidizer (a gas ...
15
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3answers
897 views

What really happens atomically in an explosion?

Let's say a room is filled with butane, I then throw a cigarette into the room. What happens to the atoms/molecules of the butane when they are in contact with the heat from the cigarette?
10
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1answer
3k views

What is the oxidation mechanism of gunpowder?

I've been recently looking into fireworks and the chemistry of explosives, and I found out that, amongst others, one of the most important reactions in gunpowder ignition is the oxidation of charcoal ...
4
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2answers
58k views

Why do unsaturated hydrocarbons burn with a sooty flame while saturated hydrocarbons burn with a clear flame when burnt in the air?

Why do saturated hydrocarbons burn with a clean flame while unsaturated hydrocarbons burn with a sooty flame when burnt in air? My chemistry book says that it happens due to the amount of carbon ...
14
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1answer
769 views

Why do some materials turn black and others white after combustion?

Most solids objects turn black after they are burnt. But some turn white. Why is that ?
12
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3answers
9k views

Why is the outermost part of the Bunsen burner flame not the hottest region?

Why is the blue flame the hottest on a Bunsen burner? I thought the outermost part of the flame must be the hottest region because of complete combustion of gases taking place there. Where am I ...
12
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1answer
14k views

Is combustion considered a redox reaction?

When carbon combusts with oxygen, is this considered a redox reaction since the oxygen atoms gain electrons and the carbon atoms lose them?
12
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1answer
733 views

What are the key chemical characteristics that determine the octane rating of fuel?

The octane rating of petrol (gasoline) is a measure of the how much compression a fuel air mixture can have before detonating (which in petrol engines is a bad thing as you want the mix to combust ...
11
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1answer
3k views

What is the difference between ignition temperature and flash point?

I am trying to clarify this for Class 8 Science. Their textbook says "It is the lowest temperature at which a substance catches fire". However, it does not clarify whether it is on its own or due to ...
10
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3answers
48k views

CH4 + O2 => CO2 + 2H2, what's wrong with it?

It says in my textbook that: $$\ce{CH4 + 2 O2 -> CO2 + 2 H2O}$$ which seems like a displacement reaction to me. Shouldn't the reaction be: $$\ce{CH4 + O2 -> CO2 + 2 H2}$$ since $\ce{4H}$ ...
9
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1answer
7k views

Why do gummy bears explode when added to hot potassium chlorate?

This link shows that a gummy bear explodes when in contact with heated potassium chlorate, $\ce{KClO3}$. But what in a gummy bear creates this reaction? Also, do other foods (fruit, icing sugar...) ...
7
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4answers
600 views

How does the presence of chlorine atoms in PVC make it flame resistant?

In a paper that I'm reading, it states that: The presence of chlorine atoms in polyvinyl chloride make it flame resistant and I'm just wondering why the presence of chlorine atoms will make it ...
6
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0answers
970 views

Sugar burning with the assistance of ash

If a plain pile of sugar (or a sugar cube) is heated with a torch, it just melts and gives off smoke. However, if some paper or wood ashes are added, it burns quite easily. What are the ingredients of ...
5
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3answers
14k views

Are there substances that cannot undergo combustion?

Are there substances that cannot undergo combustion? If so, what are they?
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3answers
2k views

Are all volatile liquids combustible?

I realized that liquids like petrol, kerosene and even perfumes are combustible when they are volatile. Could that be the reason why water is not combustible is because it is not volatile? Are ...
0
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3answers
24k views

C + O2 is equal to C + O, how is that possible

C + O = CO2 . This is because carbon has valency of 4 while oxygen has valency of 2. When they react the valencies are criss crossed which means we will get C2O4 but this is simplified to CO2. But ...
13
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1answer
1k views

Can diamond undergo a self sustaining combustion reaction all the way to carbon dioxide?

I know charcoal can smoulder in an incomplete combustion to produce carbon monoxide so I assume diamond also can. If it's heated to a sufficiently high temperature, will the reaction produce enough ...
12
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2answers
2k views

How does heptafluoropropane suppress fire?

How does heptafluoropropane suppress fire? It says here that it does so by "inhibiting the chain reaction." What does that mean specifically? Does $\ce{O2}$ attach itself to the heptafluoropropane?...
8
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3answers
837 views

How is combustion speed regulated in solid propellants?

My question on Space.SE didn't yield anything I didn't know already: the secondary regulation mechanism – grain (cross-section shape) of the propellant, changing the area of open surface of the ...
7
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1answer
249 views

Can water be ignited in an ozone atmosphere?

According to my calculations, the reaction $\ce{H2O + O3 -> H2O2 + O2}$ should be favourable under standard conditions. However, I am told that the reaction is probably very slow in solution since ...
7
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1answer
6k views

Best Fuel for Potato Gun

I have been using deodorant to propel potatoes (potato gun :D), but I want to switch over to pure butane. However, in order to do this safely I have to know how much butane is typically in deodorant (...
6
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2answers
7k views

Is there a flame which doesn't produce smoke?

I read a book where it states the following: There are many types of flame and there are even flames which don't produce smoke. After reading it, it just got stuck in my mind. Is there a flame ...
6
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2answers
23k views

What causes incomplete combustion?

During the combustion of hydrocarbons, there is a difference between the amounts of carbon or hydrogen that results in incomplete or complete combustion of the material. My question is, besides from ...
5
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2answers
247 views

Is it possible to combust a plasma?

In what we usually consider combustion your fuel and oxidizer are always neutral, but is it possible to have a similar "explosive" combustion process where both the fuel and oxidizer have been singly ...
5
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1answer
3k views

In practice, how dangerous is liquid oxygen as an oxidizing agent?

The Wikipedia page on liquid oxygen tells us Liquid oxygen is also a very powerful oxidizing agent [...], if soaked in liquid oxygen, some materials such as coal briquettes, carbon black, etc., can ...
4
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2answers
1k views

Meaning of Flammability Limits and reaction in Air of Ammonia

I have read on Wikipedia that the flammable limits of gaseous ammonia are between 15–25% and I have also read that the autoignition temperature is $651\rm~^\circ C$. And that the combustion of ...
3
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1answer
182 views

How or Why does diesel/kerosene have a much higher 'flash point' but lower auto/self-ignition point than gasoline/petrol?

This is a very common question, but I have yet to find a good theoretical answer to both questions (diesel has higher flash point BUT lower spontaneous ignition temp.)
3
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1answer
801 views

Mechanics behind auto-ignition temperature

I have some questions about the auto-ignition temperature for fuels. Per ASTM E659: AIT (auto-ignition temperature) is the lowest temperature at which the substance will produce hot-flame ignition ...
3
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1answer
27k views

What is the temperature of heat generated from LPG gas?

I'm working on a project and I require around 300-400 degree Celsius of temperature. As of now I'm taking the normal LPG gas that is available in our house for cooking purposes for my project, but I'm ...
3
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1answer
4k views

What causes the difference in heat energy released by combustion for the butanol isomers?

I am currently working on an investigation where I am burning isomers of butanol to test for the heat of combustion values to see which fuel is most efficient. The fuels I am testing are 1-butanol, 2-...
1
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1answer
113 views

How can I obtain oxygen gas from plagioclase

I would like to know if there is a possibility to decompose plagioclase to obtain oxygen gas to be used in a combustion reaction? I know that oxygen represents $47\%$ of the weight of 1 mole of ...
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2answers
1k views

Heat of combustion among substituted cyclohexanes

Arrange in ascending order of heat of combustion: I know heat of combustion is inversely proportional to stability. Also, to solve I did try making chair conformations of the substituted cyclohexane. ...
1
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1answer
323 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 ...
0
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2answers
2k views

How to calculate the amount of substances product produces from the masses and amounts of starting materials?

Calculate the amount of carbon dioxide formed when we burn 1 mole of carbon in the presence of 16 g of dioxygen. $$\ce{C + O2 -> CO2}$$ 1 mole of carbon means 12 g. Therefore amount of ...
0
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1answer
6k views

Combustion of saturated hydrocarbons vs combustion of unsaturated hydrocarbons

I read in my science book that saturated hydrocarbons burn with a blue flame (indicates complete combustion) and unsaturated hydrocarbons burn with a yellow flame (indicates incomplete combustion) due ...
0
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1answer
127 views

Additional Questions Regarding the Auto-Ignition Temperature

I had some followup questions regarding a previous post I made here regarding the auto-ignition temperature and ASTM E659 For fuel temperature below AIT, we should still have finite reactants above ...