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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How can flammable gas become inflammable when mixed with another gas with comparable percentage?

For example, R-410a is a 50-50 mixture of R-32 and R-125. R-32 is flammable (class A2L) and R-410a is not flammable (class A1). Flammability of refrigerant is mainly a concern when it is leaked since ...
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Find the equilibrium constant, Keq, for the following 2AB(g) + C2D(s) <------> A2D(g) + 2CB(s) [closed]

Find the equilibrium constant, Keq, for the following 2AB(g) + C2D(s) <------> A2D(g) + 2CB(s) {AB} = 0.556 {A2D} = 0.636
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24 views

Why does Red Phosphorus react so violently with an oxidizer like Potassium Chlorate?

In Armstrong's Mixture, mixing those two chemicals results in a friction sensitive explosive which produces a loud bang. According to wikipedia, it is made by adding a strong oxidizer to red ...
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Why does a combustion reaction always result in carbon dioxide and water?

$$\ce{CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)}$$ Here is an example of a combustion reaction. Why are $\ce{CO2}$ and $\ce{H2O}$ the result of this reaction?
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25 views

Can oxidizing agents be used to increase the combustion efficiency of waste oil?

Waste oil is atomized and combined with air to produce a very high temperature flame capable of melting iron. I was wondering if it's possible to further increase its combustion efficiency by mixing ...
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1answer
521 views

Does all fire only emit light on its outermost shell?

This question is about light emission, which may overlap with physics, but I am most interested in combustion and types of flame (incandescence, petrochemical fuel flames, nuclear ractions). Consider ...
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25 views

What is the explanation of negative temperature coefficient in ignition delay of a fuel?

When studying the ignition delay of a fuel, some fuel have a negative temperature coefficient area (NTC) where an increase of initial temperature of the mixture air/fuel produces an increase of the ...
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33 views

What happens if you superheat timber in a zero oxygen environment? [duplicate]

I was thinking to myself, what would happen if you were to put a lump of wood in a zero oxygen environment and superheat it? It couldn’t burn because fire needs fuel, heat and oxygen however because ...
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What color would be produced by the burning of the listed chemicals of the projectile weapon the carcass?

The carcass was a projectile weapon developed by the French in the second half of the 17th Century. It was "named carcass because the circles which pass from one ring, or plate, to the other, ...
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1answer
34 views

Why constant volume combustion gives higher energy than constant pressure?

I have noticed when I have done some combustion equilibrium that enthalpy is higher when doing a constant volume combustion than pressure constant combustion. Why is it so ? What are the reasons ...
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Why do nitrogen-containing organic compounds give N2 as the combustion product?

My teacher gave the explanation stating that consider that first the nitrogen in lower state is oxidised to $\ce{N2}$ and then the further oxidation would stop as the $\ce{N-N}$ bond energy of $\ce{N2}...
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55 views

Why does charcoal not produce smoke when heated?

As I understand; the reason we have smoke in a fire is because the heat causes wood (or whatever material is burning) to dis-integrate, the disintegrated components react with oxygen to create more ...
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1answer
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Finding Gibbs energy at different temperatures just given Gibbs energy at one temperature

How would it be found the Gibbs energy at a certain temperature, if they just give you another Gibbs energy at a temperature? For example: Given $\Delta G = -230 Kcal/mol$ at $773K$ for the reaction $...
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1answer
33 views

Is incineration of a solid fuel complete or incomplete?

If I have some solid material like biomass and incinerate it at 1000 Celsius degrees for 15 minutes in an oxidized atmosphere within an incineration oven. As an output it gives me ash. Is the ...
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Verify heat produced by flame using enthalpy of fomation

I'm simulating using a CFD solver a pure oxygen/methane flame. However, I doubt that the combustion model does not produce enough heat. The heat from reaction is defined by $S_h=-\sum_{j} \frac{h_j^0}{...
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1answer
49 views

What is change in internal energy of a system in which combustion occurs at constant temperature?

We got a question in a test, in which we were asked which system has zero change in internal energy and it had an option which was combustion of methane at constant temperature. I imagined this to be ...
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What causes little spikes in a flame? [closed]

I have a lighter at home which everytime I use it, generates little spikes (see picture below) which eventually disappear. The Spikes are not an effect generated by the camera. I can confirm that ...
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5answers
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Why do different substances containing saturated hydrocarbons burns with different flame?

LPG and Candle wax both contain saturated hydrocarbon, yet LPG gives a clean white flame but a candle gives yellow flame with lots of smoke. Why so? I have read some answers on web which says that it ...
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2answers
3k views

Why doesn't NASA or SpaceX use ozone as an oxidizer for rocket fuels?

Presumably, it would be expensive to use ozone ($\ce{O3}$) as an oxidizer instead of $\ce{O2}$, but would the extra oomph be worth it? Does $\ce{O2}$ provide as much thrust/energy/heat as can be ...
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54 views

Why is gasoline consisting of heavily branched alkanes better fuel than gasoline consisting of more linear alkanes? [duplicate]

As far as I know, the reason isooctane is better than octane in gasoline engines is because the octane is more prone to ignition by pressure. This makes it ignite when it is not supposed to, which ...
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1answer
71 views

Combustion of NaCl(aq) when testing conductivity

In a experiment that dealt with electric conduction of many concentrated solutions, NaCl(s) created an unknown, to me, substance after adding a drop or two of water. Furthermore, it isn't the reaction ...
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23 views

Where can I find the released combustion energy in NASA CEA rocket problem?

I am using NASA CEA program for a study project. I have read the CEA Nasa user's manual over and over, yet I haven't found an answer to my question which is : where can I found in the output of NASA ...
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1answer
93 views

Combustion of methane and ethane

I'm having trouble with the following problem: A gas fuel of Methane ($\ce{CH4}$) and Ethane ($\ce{C2H6}$) is burned with atmospheric air, and the volumetric analysis of the products of combustion ...
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1answer
22 views

Viability of reduction of oil paint binder and solvent flammability upon disposal via addition of water

As an artist, when disposing of a paper towel or cotton rag containing oil paint, turpentine, odorless turpentine substitute or mineral spirits at the end of a painting session, I generally pour water ...
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42 views

rate of combustion of alcohols and hydrocarbons in relation to the number of carbons in the chain

I understand that the heat released when burning alcohols is greater as long as the number of carbons in the alcohol chain is increased (i.e the enthalpy of butanol is greater than propanol > ...
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1answer
153 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.)
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131 views

Controlled burn with colored flames (Gender Reveal) [closed]

Is there a single solvent that can dissolve chemicals/elements that when burned, will produce the color of its respective chemical/element? If so, what chemical/element can be dissolved in this ...
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2answers
391 views

Calculating the amount of oxygen in a glass using candle burning time

I would like to calculate the amount of oxygen or concentration of oxygen in a glass or conical flask using candle burning time. I am thinking of a simple way to calculate this based on the fact that ...
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1answer
58 views

What is the opposite of a catalyst and examples? [duplicate]

I remember a while ago I heard of something that slowed reactions and was effectively the opposite of a catalyst. What is this called? Also would appreciate examples and an explanation of their uses ...
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2answers
842 views

Could blue flames arise within the hull of a burning ship?

In Joseph Conrad's Youth: A Narrative, set in 1876, a 400-ton barque ship, the Judea, is sent to Java Head to transport 600 tons of coal. Although various delays occur during its journey, the coal it ...
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1answer
190 views

What is the significance of heating value?

Say I burned for example methane and propane to boil some water. Methane has the heat of combustion of $\pu{890kJ/mol}$ and propane has the heat of combustion of $\pu{2200kJ/mol}$ What does the ...
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2answers
129 views

How much does oxygen enrichment improve some combustion engines?

This question is about how much the combustion efficiency increases with oxygen enrichment in modern combustion engine designs. A desirable way to answer is to give the fuel efficiency dependency on ...
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4answers
2k views

On heating in the Earth's atmosphere, can magnesium react with nitrogen to form magnesium nitride?

This question is derived from a question asked in my school test. What happens when a magnesium ribbon is heated in air? My first response was the formation of magnesium oxide $(\ce{MgO})$ when ...
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How to get the right formulas for combustion (rocket chamber) or where to find them? [closed]

I am a space enthusiast and am intrigued mostly by rockets. I recently found a book HOW to DESIGN, BUILD and TEST SMALL LIQUID-FUEL ROCKET ENGINES and have been fiddling around with rocket engine ...
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0answers
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Can old matches combust spontaneously?

I came upon this box of matches, it's probably from a little before 1900 and has significance for my family history, and I would like to add it to my "box o' historical items" but I'm concerned about ...
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2answers
267 views

Is reduction of copper oxide a combustion reaction?

Is the following reaction a combustion reaction or just a single displacement? Could be both? $$\ce{H2 + CuO -> Cu + H2O}$$ A friend of mine claims it is a combustion reaction because it is ...
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1answer
119 views

Water evaporation from calorimeter giving less exothermic enthalpy value?

To find the enthalpy change of combustion for an alcohol, you use a calorimeter filled with water and heat it by burning an alcohol. I was told that usually experimental values for the enthalpy ...
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69 views

is H2O in gas form in poly styrene combustion? [closed]

original question: if we burn 390g of poly styrene (STP), how much gas produces? me: 1008L my teacher: 672L he says h2o is not in gas form!(because of STP) who is wrong?
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Why is the heat of combustion of sulphur equal to the heat of formation of SO2 and not SO3

By definition the heat of combustion for compound is equal to the energy that is released on complete oxidation of one mole that substance to its highest oxidation state. In case of sulphur, online I ...
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764 views

How is octane rating defined for negative values and those over 100?

Based on my reading, the octane rating for a given fuel is calculated by finding the compression ratio at which it knocks and finding a mixture of $X\%$ isooctane and $(100 - X)\%$ n-heptane which ...
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31 views

Determining amount (in mols) of oxygen needed to fully combust coal

I'm trying to calculate the amount of oxygen needed to fully combust some coal. As an example, assume I have $\pu{1 kg}$ of coal which is, by mass fraction, 60% carbon ($\ce{C}$) 40% hydrogen ($\ce{...
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1answer
89 views

Risks of burning melamine formaldehyde adhesives [closed]

Background- I make biochar for gardening, and small scale carbon capture and storage. Most of my feedstock is clean, unpainted, untreated, end of life timber, but there is a small proportion of ...
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2answers
129 views

Sulfates and persulfates as accelerants in black powder?

I saw there was a few black powder posts on here so I'd like to pose a question. Would sulfates or persulfates like the oxidixer soduim persulfate be a good replacement for some percentage of the ...
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104 views

Adiabatic flame temperature of hydrogen peroxide calculation

I will first demonstrate my cursory method for evaluating the adiabatic flame temperature of H2O2 at atmospheric pressure. $$\ce{H2O2 -> H2O + 0.5O2}$$ At $\pu{1200 K}$, \begin{align} h_\ce{...
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3answers
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What is the best way to make a substantial amount of soot in a high school laboratory?

I need to make about 50 grams of soot (carbon black particles) in a high school laboratory. What would be the best way to do this? The purpose of needing 50 grams of soot is because I would like to ...
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2answers
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Why does Sodium Bicarb. Reduce Combustion Rate? [closed]

In many common solid-propellant model rocket engines, Sodium Bicarbonate, $\ce{NaHCO3}$, is used to predictably regulate/limit the rate of combustion of the fuel. My questions are as follows: What is ...
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1answer
948 views

Rocket Candy Fuel - Common Alternatives to KNO3?

I'm sort of a model rocket enthusiast, but the most common fuel for model rockets, Rocket Candy, requires Potassium Nitrate as an oxidizer to oxidize Powdered Sugar. Potassium Nitrate is not ...
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1answer
68 views

What is the characterstics of additives that it must posses to make any mixture hypergolic? [closed]

This is about hypergolicity of rocket propellant.Turpentine gave hard-start with RFNA and WFNA but excellent with mixed acid(mixture of HNO3 & H2SO4).Similarly,Furfuryl alcohol & WFNA(also ...
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1answer
577 views

Heats of combustion of cycloalkane homologues

Heat of combustion increases as the number of carbons increases, but on comparing ethyl cyclopentane, ethyl cyclohexane, andethyl cycloheptane, shouldn't you consider ring stability too? In that ...
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1answer
2k views

Can someone help me find the limting reagent? [closed]

Okay, so for home work i was given this problem. Suppose that 8.00g of CH4 reacts with 16.00g O2 to form CO2 and H2O, find the grams of CH4, H2o, and O2 left over Balanced Equation : CH4 + 2O2 = ...

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