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Hot answers tagged combustion

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Why doesn't water burn?

You can think of water as the ash from burning hydrogen: it's already given off as much energy as possible from reacting hydrogen with oxygen. You can, however, still burn it. You just need an even ...
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Why doesn't water burn?

This is the reaction that occurs when hydrogen combusts: $$\ce{2H2 + O2 -> 2H2O}$$ Similarly, this is the combustion reaction for methane, a representative fuel:  \ce{CH4 + 2O2 -> CO2 + ...
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Why does shaking a match put the fire out?

Combustion of small materials, such as a match or birthday candle, actually involve the release of volatile vapours, which themselves burn. It is not the solid material that burns. There needs to be a ...
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Why does wood burn but not sugar?

Combustion is a gas phase reaction. The heat of the flame vapourises the substrate and it's the vapour that reacts with the air. That's why heat is needed to get combustion started. Anyhow, wood ...
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Why doesn't water burn?

$\ce{H2O2}$ exists, and could be what you expect by burning water (since burning is really oxidizing, or adding oxygen.) However, in stoichiometric proportions, here is what would happen: Either ...
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Why doesn't NASA or SpaceX use ozone as an oxidizer for rocket fuels?

As is usual with rocket fuels, the problems of ozone are practicality not performance Almost every answer for why a specific rocket fuel component is used or not will end up referring to John D Clarke'...
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Does any known substance ignite on cooling?

Actually... yes! Iron(II) oxide is thermodynamically unstable below $848~\mathrm K$. As it cools down to room temperature (it has to do it slowly) it disproportionates to iron(II,III) oxide and iron: ...
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Why do the alkali metals form different products upon combustion in air?

Since I will deal with all of the alkali metals in this answer, I think the question should also be broadened. There is no point in covering one single metal (sodium) without touching the others since ...
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Would the concentration of oxygen around fire increase as we get close to the fire (from the outside)

A fire has no way to directly "draw in" oxygen for it to burn. It consumes what oxygen is in the immediate vicinity of the flame, depleting the air in oxygen compared to the concentration of oxygen in ...
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When a candle burns, why does the top of wick glow if bottom of flame is hottest?

The wick temperature does not have to be the same as the flame temperature.The flame is hottest at the bottom, but the wick is hottest at the top. For a candle, the wick burning isn't the intended ...
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When a candle burns, why does the top of wick glow if bottom of flame is hottest?

Because fire is not the same thing as light. Michael Faraday did a wonderful job of explaining how the candle works, and I direct you to look at it (there are also Youtube videos giving a modern take ...
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Can flames be colored black?

This video shows how a black flame is achieved. If you illuminate the fire with a monochromatic light source (sodium vapor lamp) and introduce a species in the fire that absorbs that wavelength (...
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How do self-relighting (trick) birthday candles work?

In normal candles, as you blow them out, you will see burning embers in the candles, which vaporises the wax and thus causes a ribbon of paraffin wax to rise up (this looks like a wisp of smoke). ...
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On heating in the Earth's atmosphere, can magnesium react with nitrogen to form magnesium nitride?

A large pile of grey magnesium powder, when lit in air, produces a smouldering pile which cools down to reveal a crusty white solid of magnesium oxide. However, if you break apart the mound, you can ...
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How can solids undergo combustion if it only occurs in the gas phase?

Combustion is a gaseous phase phenomenon. Oil and gasoline have a high enough vapor pressure at ambient temperatures to produce a gaseous phase of fuel above the liquid. In contrast, hold a lighter up ...
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Why doesn't water burn?

This becomes intuitive once you accept that any chemical compound will 'want' to be in the state with the lowest energy, the ground state for a given temperature and pressure. For example, if you plot ...
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Why doesn't the carbon dioxide produced by a fire put out said fire?

The fuel for the chemical reaction is the CH4 (in this case) and the oxygen. Assuming the CH4 isn't going to run out any time soon, the chemical reaction will continue as long as there is enough ...
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Why doesn't NASA or SpaceX use ozone as an oxidizer for rocket fuels?

Liquid ozone is rather stable (as in "can be stored") as an up to 70% solution in LOx, if you add some stabilisers. That would give quite a bit of additional boost in a rocket, but it's ...
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What are the differences between diesel and unleaded gasoline?

Diesel engines vs. gasoline engines Diesel engines don't rely on spark plugs, but they still work by igniting the fuel to generate a force that moves a cylinder in the engine. The air/fuel mixture ...
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What is the mechanism of alkane combustion?

The following, very general radical reactions apply to any common combustion reaction of organic material. Details vary largely. Step 1 An energy spark of whatever kind turns triplet oxygen into its ...
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