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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9
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1answer
625 views

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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0answers
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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
170 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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2answers
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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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3answers
2k views

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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2answers
850 views

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
138 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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0answers
144 views

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
65 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
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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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3answers
5k views

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
664 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
14k views

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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7answers
4k views

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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2answers
4k views

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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0answers
66 views

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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0answers
79 views

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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0answers
141 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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3answers
2k views

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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3answers
533 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
208 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
780 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
46 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
92 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
445 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
338 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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2answers
2k views

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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2answers
3k views

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
837 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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3answers
4k views

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 ...
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 ...
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0answers
59 views

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
1k views

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
105 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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3answers
13k views

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 ...
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?...
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1answer
35 views

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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1answer
1k views

Combustion of non-hydrocarbon organic compounds

When we learned about combustion, we learned about the combustion of hydrocarbons and compounds with only hydrogen, oxygen, and carbon. However, how would combustion work with compounds that contained ...
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1answer
1k views

How do self-relighting (trick) birthday candles work?

You may have seen those birthday candles, where, upon blowing them out they smoulder for a bit and then (magically) relight. How do they work? Why can't regular candles do this (is it possible for a ...
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1answer
61 views

Usage of ammonia as odorant in fuel gases

Usually, thiols such as ethanethiol are added to fuel gases to warn the user of a leak. Why is a few percent of ammonia not used instead? Ammonia is flammable so it will burn to nitrogen and water in ...
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2answers
826 views

Spectrometry in Chemistry & Flame Test Lab

Question 1: You currently see two colors that are two similar (dark yellow and orange) in a flame test lab. And also you have a hard time differentiating the colors, what is an alternative to ...
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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?
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3answers
2k views

Why can wood burn all the way to charcoal instead of just creating a passivating charcoal layer?

I know burning to charcoal is actually incomplete combustion because charcoal can also burn. When a strike anywhere match burns, it burns all the way to charcoal but the charcoal doesn't further burn. ...
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 ...
5
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2answers
452 views

Oxidation of malonic acid

Question How many grams $\ce{CO2}$ will result when burning $\pu{100 g}$ malonic acid? The formula for malonic acid is $\ce{C3H4O4}$ so 3 $\ce{CO2}$ molecules should result from oxidating one ...
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0answers
139 views

Which one is the healthiest to operate a lantern with: kerosene, diesel or sunflower oil?

Given a lantern (originally made for kerosene) however, I'm looking for the fuel which is the safest for indoor use. I've already tried different kinds, and found three of them that burn just as ...

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