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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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 ...
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Why does old gasoline seem to have more “kick”?

From my personal experience, old gasoline (leftover in a container from the previous year) has more "kick" (power) when I actually use it. Higher idle RPM, higher throttle sensitivity. It says here ...
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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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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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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 ...
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Is a combustion necessarily a redox-reaction or can there be exceptions?

I have a feeling that I have heard of an exception - either based on the material or the oxidizer.
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1k views

Finding average Mr of a gaseous mixture

A 2 g mixture of cyclohexanol, acetone and pentanal is completely burnt in oxygen. When the gaseous product is passed through $\ce{P2O5}$, the mass of $\ce{P2O5}$ increased by 1.998 g. Find the ...
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2answers
425 views

Spontaneous combustion of sulfur in a steel barrel

Got some free sulfur. Went to the site, and they put a pallet with 3 barrels on it. One of the barrels was badly corroded, but looked like I could get it home. I had plastic barrels at home that I ...
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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 ...
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Is the flame temperature of a burning fuel affected by pre-heating the fuel?

This page on Adiabatic temperatures helpfully lists the theoretical maximum temperatures that flames will reach under certain conditions for a number of fuels. They assume initial atmospheric ...
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1answer
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Understanding smoke chemistry of tobacco and/or marijuana

In an effort to understand the effects of tobacco vs marijuana smoke on health, the chemistry of smoking plants, and remembering some of the chemistry I took in college, I came across a 2007 study ...
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In a jet or internal combustion engine that burns hydrogen as a fuel, what would happen if you replaced the hydrogen with deuterium? [closed]

Would it increase the power of the jet engine due to heavier atoms being exhausted out the back? For the same reason would it slow down an internal combustion engine?
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How to evaluate enthalpy variation of combustion of sucrose in a constant volume calorimeter?

Consider combustion reaction (with the formation of $H_2O$ and $CO_2$) of a mass $m$ of sucrose in a constant volume calorimeter with thermal capacity $C$. This reaction increases the temperature of $...
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1answer
173 views

Can hydrogen alone be used as a fuel? [duplicate]

I have always thought that fuel such as petrol, diesel, etc.. are getting burnt to move the pistons in the car (I am not bringing physics). Why not hydrogen be used as a fuel but I know the incident ...
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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 ...
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Is graphene a combustible material?

Various sources such as https://news.ycombinator.com/item?id=7679154 speculate that graphene will combust at higher temperatures. Is this true? Is the flash point/ temperature of combustion for ...
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Why is the enthalpy of combustion higher for n-butane as compared to 2-methylpropane?

N-butane has an enthalpy of formation of $\pu{-125.6 kJ/mol}$, whereas it is $\pu{-134.2kJ/mol}$ for 2-methylpropane. When comparing the heat set free at the combustion process, why is it higher for n-...
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1answer
147 views

Combustion of Rocket-Candy with Fe2O3

We know from Wikipedia that the combustion of rocket candy follow this equation : $\ce{48 KNO3 + 5 C12H22O11 → 55 H2O + 36 CO2 + 24 K2CO3 + 24 N2}$ We can add small quantity of iron (III) oxide ($\...
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What would be a suitable non-combustible lubricating oil or compound for a very high pressure air compression system?

This question came up at Engineering SE but remains unanswered. If we are compressing regular air, not nitrogen, what oil or compound can be used that would not combust with the oxygen in the air. ...
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1answer
68 views

Aluminium, heat and biological safety

I'm currently working on a really simple project, an ashtray that can stop cigarette combustion. I planned to put an aluminium block into my ashtray, with some kind of curves or holes in it, in order ...
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1answer
2k views

Why does diesel have a higher energy density than gasoline?

One of the primary reasons why hydrocarbons produce energy is the production of water during the combustion process. I've been trying to find out why diesel is considered to have a higher energy ...
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How do you melt magnesium without causing its combustion?

How do you melt magnesium without causing its combustion? I own a foundry capable of reaching temperatures around 2000 °F, and I recently bought some magnesium for melting before doing my ...
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1answer
691 views

What types of ultraviolet light will ignite hydrogen?

I saw a reaction between hydrogen and chlorine ignite in the presence of UV light. I was wondering if the same thing would happen with something like near-ultraviolet light (around 400 nm). What kinds ...
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1answer
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What is behind of the attraction between a burned matchstick with a magnet?

I do not know how to understand the reasons of why a burned matchstick is attracted by a magnet (most probably) of Neodymium. Here are some screenshots of a video in which this natural phenomenon is ...
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1answer
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Why does hydrogen burn with a pop sound?

Our teacher made us to do an experiment with zinc granules and hydrochloric acid. $$\ce{2HCl + Zn -> ZnCl2 + H2}$$ We collected the hydrogen gas that was evolved in a test tube and on ignition, ...
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Examples of non-volatile, but flammable liquids?

As far as I know, most flammable liquids are volatile. Are there flammable liquids that are non-volatile?
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Why is oxygen so special?

Why do reactions with oxygen produce flame (i.e. light), heat and hence a lot of energy? I mean, why only oxygen, why not any other element like nitrogen? What is special about the electronic ...
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Why won't my propane combust when I spark it?

I need to run an experiment and have some pretty basic questions. I'm trying to get combustion of propane in a controlled environment. I understand that that looks like this: $$\ce{C3H8 + 5O2 -> ...
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What happens when I divide two molar flow rates in a chemical equation?

I don't quite know how summarize my question in the title. I have a combustion process given by this equation: $$\ce{C10H22 + 15.5 O2 + 58.25 N2 -> 11 H2O + 10 CO2 + 58.25 N2}$$ This process ...
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142 views

Is it true that when hydrogen reacts with oxygen to form water, that if first forms an hydroxyl radical? [closed]

When I took chemistry in high school, the inevitable question as to whether or not water has a chemical name came up. Our instructor said no, but if it did it ought to be called hydrogen hydroxide. ...
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Why is it wrong to calculate the amount of oxygen directly from the products of a combustion reaction?

I've been stumped by a question in my textbook concerning combustion analysis. A $\pu{0.5438g}$ sample of a liquid consisting of only $\ce{C}$, $\ce{H}$, and $\ce{O}$ was burned in pure oxygen, ...
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557 views

Why does internal combustion engine smoke appear blue? Could there be “blue molecules” in it?

Four-stroke and two-stroke gasoline engines as well as diesel engines can all emit dense clouds of blue-tinged smoke under various transient loads or incorrectly tuned conditions. Raleigh scattering -...
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1answer
266 views

Reacting carbon dioxide with magnesium in ribbon form

My experiment involves a reaction of magnesium in ribbon form with that of carbon dioxide. I know that the product shall be magnesium oxide (white powder) and carbon (black powder) but I do not know ...
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1answer
817 views

Can hydrocarbons undergo combustion without oxygen present?

Most of us are familiar with the standard reaction of methane gas combustion: $$\ce{CH4 + 2O2 -> CO2 + 2 H2O}$$ In standard combustion, oxygen is generally used as the oxidant. Would it be ...
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1answer
47 views

Can an improvised torch be made to last for a prolonged period of time?

In the movie First Blood, there is a scene where Rambo is trapped in a cave after escaping a bazooka rocket that caused the mine he was hiding in to collapse. After realizing the entrance has been ...
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2answers
93 views

Can we chemically characterize a flame? [closed]

Can we chemically characterize a flame ? Recently, while I was lighting a candle, I came across this question; can we find out the chemical composition of a particular flame? If yes then how? In ...
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1answer
453 views

How does the degree of saturation influence the colour of the flame?

If the colour of flame produced by the atom of an element is the property of that element then why do unsaturated and saturated carbon compounds give different colours of flame even though both ...
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1answer
349 views

Does benzene vapor react with air in a closed barrel?

If we would have benzene in a closed barrel for quite a while at room temperature, some vapor would form fast due to its volatility, right? But let's say that when the barrel was closed, some air got ...
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Is liquid hydrogen rocket propeller pollution free?

If one searches for the different fuel types used in rockets, one can find that over the years, NASA and other space agencies have used both solid fuels and liquid fuels. I can see that more and more ...
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Why should fire extinguishers containing carbon dioxide not be used on magnesium fires?

As the title states, why should $\ce{CO2}$ fire extinguishers containing carbon dioxide not be used on fires with magnesium metal? I understand that $\ce{CO2}$ extinguishers work by displacing oxygen,...
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3answers
861 views

Calculating standard combustion enthalpy of dodecane from that of heptane & octane

These are the problem from UKChO-2015. Given the standard enthalpy changes of combustion ($\Delta_\mathrm{c}H$) for heptane ($n = 7$) and octane ($n = 8$) are $-4816$ and $-5470~\mathrm{kJ~mol^{-1}}...
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Why is compressed air flammable?

I have a can of compressed air. The type you use to clean the insides of computer. It's "100% ozone friendly" and "pure compressed gas". So I assume its everyday regular breathable air. I used it to ...
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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 ...
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How much energy can be produced by burning sewage gas?

I am an eighth grader. I need to make a science project on the production of electricity from sewage. I know that almost sixty percent of sewage gas is Methane and most of the other constituents are ...
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1answer
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What single, pure compound would best replace petrol?

Petrol for use as automotive fuel is produced by blending of different product streams of oil refining. It consists of hundreds of different compounds, and the exact composition can vary widely. ...
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0answers
106 views

Chile 2017, One of the Largest Fires in South America: Wood Ash Derivates for Industrial Applications [closed]

Hi: We're a group of people who wants to help people, domestic animals and wildlife recovering from this fire. Summary: We're having in Chile one of the largest fires in South American history. More ...
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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 ...
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Why are hydrocarbon flames yellow or blue?

A candle gives a yellow flame while kerosene gives a blue flame on burning. Now, saturated hydrocarbons give a blue flame but unsaturated ones give a yellow flame. I want to know why the colour of the ...
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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?...
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1answer
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If propane with specific parameters were to combust in open air, what is actual volume of CO2 produced

Lets say we have a sample of propane gas having a volume of 2.70 L at standard room temperature and 1.75 atm. This gas is exposed to our air. The equation that governs this reaction is: $mC_3H_8 + ...

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