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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4
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2answers
59k 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 ...
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262 views

Why are fires smokey?

Combustion, in chemical terms, is a reaction with a certain molecule and oxygen, and it produces, energy, $\ce{CO2}$, and $\ce{H2O}$ (That's how I learned it at least). So what makes a fire'smokey'? I ...
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1answer
292 views

Can carbon subnitride be used as a fuel with similar properties to gasoline?

I am trying to figure out if Dicyanoacetylene, aka carbon subnitride, aka $\ce{C4N2}$, can have a similar reaction with air as gasoline, or if it only creates a lot of heat but not much expansion? As ...
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1answer
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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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2answers
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What temperature is required to burn pencil lead graphite?

I tried to burn a bunch of 8B pencil lead in a gas flame the other day. None of it actually caught fire, but being made of carbon (in the form of graphite) should cause it to burn, as graphite is ...
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0answers
37 views

Can oxidizing agents act as comburents?

Comburent, to the best of my knowledge, refer to substances that catalyze combustion reactions without reacting itself or being flammable independently, such as potassium chromate. How would oxidizing ...
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2answers
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What's the composition of gun smoke and is it dangerous?

Background I've been conducting an informal (i.e. mental) risk assessment of visiting gun ranges. There are a couple of obvious sources of hazard: Injury by bullet Hearing loss Hot casings flying ...
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1answer
399 views

Why does microwaving napalm make it nonflammable?

In this video, microwaving napalm made it nonflammable. What caused this to happen? I assume it was some sort of chemical reaction. Could someone explain? I understand some chemistry, but a not-too-...
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What makes a glowing splinter glow and a burning splinter burn

This question bugs me for years since I started learning the oxygen, carbon dioxide and hydrogen tests. I know you can make a glowing splinter burn when doing the oxygen test due to enough oxygen. But ...
3
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1answer
352 views

What is the meaning when it is said “Temperature of an Oxyacetylene Torch is 3500 degrees Celsius”?

I don't think flame is anything but the product at that temperature but I am not sure. What exactly is flame? And I think the correct statement should be that the exothermic reaction here produces ...
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Controled burn colored fire and safety

I am a martial artist who uses fire weapons in my shows. I am wondering how I can get the flames to be different colors. I've done some research about it, and have found that the salts of some ...
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1answer
208 views

What proportion of a combustion engine's output energy comes from the air?

When trying to compare the efficiency and range of electric engines vs gasoline engines, it seemed at first that gasoline had a higher energy density than batteries. But then I realiced that a ...
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1answer
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Heat of combustion of stereoisomers of 1-tert-butyl-2,4-dimethylcyclohexane

Which of the compounds below has the smallest heat of combustion? I know that the heat of combustion is indirectly proportional to the stability of a molecule. And here both $\ce{CH3}$ and $\ce{C(CH3)...
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Why do branched hydrocarbons burn more efficiently (complete & clean combustion)?

Branched and cycled hydrocarbons usually a higher octane number than their straight chain counterparts. This is due to a more complete and clean (no residue) combustion. In addition, there is no ...
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1answer
121 views

About how much carbon monoxide is produced in these two different reations?

The U.S. Department of Agriculture produces a gas cartridge to poison subterranean rodents. The product is provided as a cardboard tube sealed at one end and then loaded with a mixture of 144.6 grams ...
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1answer
143 views

To what degree an N99 active coal filter can protect against products of burning paraffin oil?

I sometimes do firedance and a part of it is waving a stick with burning endings made of Kevlar soaked in paraffin oil. I started to be a bit concerned about how healthy is it to inhale lot of ...
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How can titanium burn in nitrogen?

I was going through the properties of titanium when a certain thing caught my eye: It was the reaction of burning of titanium in nitrogen. I was astonished to read it as I knew that neither is ...
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0answers
130 views

Characterization of products of non-stoichiometric combustion

To give some background, I'm looking at this from an aerospace standpoint as to the calculation of the efficiency of a propellant reaction at a given oxidizer-fuel ratio. That efficiency is a ...
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1answer
187 views

At what temperature do complex hydrocarbons become ashes?

When heating a metal tube with polypropelene in it, i found that i still had brittle black foam and flakes in it even though it had been in a blue flame at around 500'C What happens to complex ...
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1answer
651 views

How much CO2 gets free when combusting 6 kg n-heptane (C7H16) [closed]

I am very new to chemistry and have a question to an exercise. It's about combustion (complete oxidation) n-heptane ($\ce{C7H16}$). There were several questions I could answer, for example the ...
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1answer
10k views

How much CO2 is produced in burning of a candle?

I've been reading this book, page 149. In chapter 15 the following experiment is suggested, Fix a candle in a container. Fill the container with water. Light the candle and then cover it with an ...
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How to define a flame in numerical combustion?

I am running a CFD simulation (computational fluid dynamics) opposed jet case, where a stream of fresh reactants is opposed to a stream of burnt products. I am looking at the effects of stratification ...
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1answer
1k views

What defines incomplete combustion?

I know that complete combustion is a process where a fuel reacts with $\ce{O2}$ to become $\ce{CO2}$ and $\ce{H2O}$. But what is incomplete combustion? According to the Internet, $\ce{CH4 + O2}$ and ...
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1answer
1k views

Why does burning wood produce methane and other hydrocarbon chains?

This post kinda helps me understand and it sounds like it has to do with pyrolysis, but I'm having trouble putting the exact reactions together.
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Why is the smell of car exhaust much stronger in winter?

I noticed that in winter, the smell of cars (to be precise the smell of the exhaust gases) is much stronger in winter. I just can't figure out why. Has this got something to do with the air ...
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1answer
2k views

Which element is undergoing oxidation in the combustion of methane?

Chemical reaction: $$\ce{CH4(g) + 2O2(g) -> CO2(g) + 2H2O(g)} $$ The example in our textbook for this type of problem involves the following reaction: $$\ce{C + 2S -> CS2} $$ Here, I can ...
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1answer
116 views

Why is the sneaky method of smothering a grease fire more effective?

In this demonstration, a grease fire is temporarily extinguished if you put the cover on the pan, but reignites as soon as you take the cover off. However, if you slowly slide the cover across the ...
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1answer
302 views

Combustion properties of Dimethyl Ether

I have a C++ code which calculates the combustion thermodynamic variables (temperature, density) and the mass fractions of Dimethyl Ether for different equivalence ratio. I would like to check my ...
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Understanding the energy produced from oxidizing 1 kg of lithium

I am reading the following paper in preperation for a research project on the theoretical energy density of batteries: Lithium - Air Battery: Promise and Challenges and on the second page they ...
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1answer
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Calculate the mass of butane gas that would be needed to heat 724 cm³ of water from an initial temperature of 7.44 °C to 50.7 °C [duplicate]

The thermochemical equation for the combustion of butane is: $$\ce{2C4H10(g) + 13O2(g) -> 8CO2(g) + 10H2O(l)} , \quad\Delta H = -5748 \ \mathrm{kJ\cdot mol^{−1}}$$ So far, I've calculated the heat ...
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1answer
1k views

Calculate the amount of energy released when 500 cm³ of methane gas at STP reacts with excess air according to the equation:

$$\ce{CH4(g) + 2O2(g) -> CO2(g) + 2H2O(l)} \qquad \Delta H = -890\ \mathrm{kJ\ mol^{−1}}$$ I am not totally sure how to work this out. What I did, though, was: $\ce{CH4}$ $M = 16\ \mathrm{g/mol}$...
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2answers
823 views

Does combustion occur more easily at higher oxygen concentrations or just higher oxygen partial pressure?

I saw a trailer for The Martian and started thinking about space flight. I know that spacecraft and spacesuits often operate at low pressure with high oxygen content (near 100% $\ce{O2}$ at about 20 ...
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1answer
622 views

Optimal CFM for kerosene to burn?

I am going to be making a kerosene forge, and I need a refresher on calculus-based chemistry. Given a certain distribution of alkanes, what is the amount of air (21% O$_2$) needed (in cubic feet per ...
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431 views

Could the net equations for burning hexene be used as a means of energy source?

$6\ce{CO_2} + 6\ce{H_2O}\xrightarrow{some\;catalyst}9\ce O_2 + \ce{C_6H_{12}}$ $\ce{C_6H_{12}} + 6\ce O_2\to 6\ce{CO_2} + 6\ce H_2$ $6\ce H_2 + 3\ce O_2\to 6\ce{H_2O}$ At one point, I had made a ...
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1answer
115 views

Does the ignition point of flammable substances changes when provided a pure oxygen atmosphere?

I'm wondering if autoignition point decreases for substances when provided higher oxygen concentration.
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3answers
10k views

Is liquid oxygen non flammable?

Every one knows that liquid oxygen is flammable, but why this tank labeled like this: so is it really liquid oxygen is non flammable?
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0answers
295 views

Bond Dissociation vs Hess' Law Enthalpy

I am trying to determine two of the theoretical values for the enthalpy of the combustion of methanol. I have calculated (using Hess' law) that the $ \Delta H_{\mathrm {reaction}}\; = -1453.418~\...
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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 ...
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1answer
1k views

Paper Towel Soaked with Isopropanol/Water Mixture Burns without Damaging the Paper. Why?

Video: https://www.youtube.com/watch?v=_qFN1hDZwp8 If you choose not to view the video, in the first demonstration a paper towel is soaked in isopropanol. As expected, the paper towel burns. However, ...
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1answer
635 views

Combustion without hydrogen [closed]

Is there any fuels without hydrogen that will combust. My friend believes there might be and do to my experience I have never heard of one. Please explain and if u can show a balanced equation of this ...
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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 ...
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0answers
626 views

Is white phosphorus really a cool burning fuel?

About 11 months ago, I posted a question on this SE site on cool flames. One of the answers mentioned white phosphorus. However, a few weeks earlier, I played a game called Spec Ops: The Lines, in ...
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1answer
6k views

How to calculate the amount of water produced by the incomplete combustion of propane?

I was wondering if someone could walk me through how to do the following two questions? The complete combustion of pentane has a enthalpy change of $-3509~\mathrm{mol^{-1}}$. Write an equation ...
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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-...
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1answer
64 views

What factors are influencing a woosh rocket?

I asked this over at Physics, but no one seemed to know, so I'll try here: If I fill a plastic bottle with a small amount of rubbing alcohol, shake it around and hold a match to the bottle neck, I'll ...
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1answer
2k views

Determining stoichiometry of an unsaturated hydrocarbon via combustion

$60\ \mathrm{cm^3}$ of oxygen was added to $10\ \mathrm{cm^3}$ of a gaseous unsaturated hydrocarbon. After explosion and cooling to room temperature, the residual gases occupied $45\ \mathrm{cm^3}$. ...
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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 (...
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2answers
11k views

Determining the Equivalence Ratio

Determine the equivalence ratio of the following mixture: 4g of Butane, $\ce{C4H10}$, and 75 grams of air. Answer is 0.82 Ok so I try converting everything into mols $4~\mathrm{g}~(\ce{C4H10}) \...
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1answer
3k views

Why is the maximum adiabatic temperature found for an equivalence ratio a bit higher than 1?

Why does the peak adiabatic temperature usually happen for an equivalence ratio a bit higher than 1? I think it had something to do with the probability of each fuel molecule finding a corresponding ...
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What are the differences between diesel and unleaded gasoline?

I am curious about the flammability of diesel fuel and its properties, as I don't deal with it on a regular basis (at all). In particular, I want to know how the fuel works when powering a diesel ...

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