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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1answer
132 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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23 views

how to compare performance of two propellants?

I want to figure out how many grams of ANFO would be needed to substitute 1 gram of nitrocellulose as a firearm propellant. I have available energy per gram of both substances and I can figure out the ...
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47 views

Can a combustion process be more energy efficient with oxygen enrichment?

I wonder if a combustion process with air as oxidant can benefit by oxygen enriching the air intake? By benefit I mean if the net energy output would be positive, or negative, since the enrichment ...
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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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22 views

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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40 views

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
65 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
42 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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1answer
68 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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27 views

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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662 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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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
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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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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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59 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
78 views

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
38 views

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
98 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
52 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
197 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
63 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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When I burn isopropyl alcohol (IPA), it burns orange. But when I burn ethyl alcohol, it burns totally blue. Why is this?

I burned them in a small aluminium tray. While IPA is burning orange, it produced the smell of soot, but while ethanol is burning blue there isn't any smell. Also, ethanol made the tray really cold ...
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25 views

Combining enthalpies of formation and combustion in the context of Hess's law

I know that you can use enthalpy of combustion to work out formation, and Formation to work out enthalpy change. But can you use enthalpy of formation and combustion data is the same Hess's cycle to ...
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1answer
69 views

Are petroleum-based products prone to produce hard residues with black powder?

A common controversy about black powder is lubricant composition. Some people tell this is a bad idea to use any petroleum based products in such lube because it will produce hard, difficult to clean ...
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28 views

Determining the Heat Capacity during a combustion in a bomb calorimeter

The combustion of $\pu{2.350 mmol}$ of $\ce{X}$ caused the temperature of a bomb calorimter to rise from $23.700 °C$ to $26.300 °C$. Assume $T = 25.000 °C$, $H_\text{comb} = -3310 \frac{kJ}{mol}$, and ...
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65 views

A sealed container contains 90 % hydrogen and 10 % oxygen. There is a spark in the container. What happens? [closed]

A sealed container contains 90 % hydrogen and 10 % oxygen. There is a spark in the container. What happens? Assuming it is a 10-litre volume container like a fuel tank.
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33 views

What is the result of the combustion of the mixture?

I prepared a little experiment about solid rocket propulsion. I have used water ($H_{2}O$), potassium nitrate ($KNO_{3}$) and saccharose ($C_{12}H_{22}O_{11}$). I made the mixture in a pan by cooking ...
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1answer
55 views

How to determine the composition of a gas mixture after a combustion?

The problem is as follows: A mixture of gases consisting of $\ce{CH4}$ and $\ce{C2H4}$ is let to pass over red hot $\ce{CuO}$. Then $\pu{0.6g}$ of $\ce{H2O}$ is collected along $\pu{1.185g}$ of ...
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1answer
51 views

Is it possible to obtain the amount of air required for a combustion analysis?

I'm not very sure if the required amount of oxygen (I assume) can be found by only knowing the amounts of the produced subtances after a combustion. To illustrate this I found this problem: $1.14\,...
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1answer
28 views

How does the vapor pressure in a vessel affects the total pressure after a combustion reaction?

The problem is as follows: A sealed container of $3\,L$ in capactity is filled with hydrogen and oxygen at $314\,torr$ each one at a temperature of $27^{\circ}C$. A spark produces the reaction ...
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81 views

Is it possible to have a negative overall activation energy for a whole reaction mechanism?

I am trying to find out correlation for ignition delay for alkane fuels. The activation energy part of the correlation gives me a negative value. For the ignition delay formulation, is it possible to ...
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1answer
52 views

Fires with chlorine

could a fire with it's fuel consisting of mostly carbon like coal or wood use chlorine instead of oxygen. My thinking goes that when fire burns it sucks in oxygen and that bonds with carbon to make ...
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203 views

Equation of combustion of heavy fuel oil (HFO)

We are researching the use of heavy fuel oil (HFO) on ship vessels, but are having trouble finding the equation of the chemical combustion process of HFO. I understand that it contains long chains of ...
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1answer
35 views

Calculating ΔH with non-integer coefficients in the balanced equation

I am working a practice problem out Ebbing's General Chemistry and for part of the problem I needed to calculate $ΔH.$ The problem considers the burning of ethane in oxygen to yield carbon dioxide and ...
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2answers
73 views

Hess's Law and ΔH

Target equation: $\ce{Mg(s) + 1/2 O2 -> MgO(s)}$ $$ \begin{align} \ce{MgO(s) + 2 HCl(aq) &-> MgCl2(aq) + H2O(l)} &\quad ΔH &= \pu{-1300 kJ} \tag{1}\\ \ce{Mg(s) + 2 HCl(aq) &-&...
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131 views

Why polyethylene (PE), wool (polyamide) and cotton (cellulose) burnt with different smells, while they just product CO2 (and N2)?

Both PE and cotton produce CO2, but they distinctly have different smells while being burnt (Burning PE has smell of candle wax, while burning cotton’s smell is like burning leaves). Wool produces CO2 ...
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549 views

Deciding the order of heat of combustion of isomeric alkanes

I'm asked which one of the alkane has the lowest heat of combustion (note: the question says heat, not enthalpy) and according to the answers, the right one is d. I'm trying to understand why d ...
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1answer
31 views

Combustion and pyrolysis of sulfides and organosulfurs

Last week there was a huge fire in french chemical factory Lubrizol, we now know the main products that burnt, to simplify the discussion I extracted a few compounds: isobutyl and isobutene ...
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2answers
151 views

Why are wet things harder to ignite than dry things? [closed]

Specifically wood and paper and other hydrocarbons, but not necessarily excluding other things that burn. We all know wet wood is very hard to ignite. Wetness here refers to water. But why is that ...
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232 views

Is it possible to blow out a candle flame using pure oxygen?

This sounds like a stupid question perhaps, but if a stream of pure $\ce{O2}$ was directed at the flame as a concentrated jet would it blow off the candle?
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Are all volatile liquids combustible?

I realized that liquids like petrol, kerosene and even perfumes are combustible when they are volatile. Could that be the reason why water is not combustible is because it is not volatile? Are ...
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1answer
64 views

Using an oxidizing agent to improve combustion of a fuel [closed]

If I were to add an oxidizing agent like dilute Potassium permanganate (aq) to a potential fuel such as plastics (polystyrene etc), would the combustion of this fuel be more complete ie: less sooty ...
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1answer
69 views

Ventilating combustion byproducts in water heaters

I'm designing a system which will heat up water by burning natural gas which is commonly available. I would like to have a slow flame because water will need to reach $\mathrm{70^\circ C}$ and stay ...
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0answers
60 views

What Is The Heat Of Combustion Of Diesel And How Do I Find It? [closed]

I need help in finding the heat of combustion of diesel, no where online can i find it, and my chemistry teacher does not know how to find it....
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42 views

How do you find the heat capacity ratio of combustion products?

For example, if gaseous oxygen $(O_2)$ and paraffin wax $(C_{32}H_{66})$ were to stoichiometrically combust at STP, how would one go about finding the heat capacity ratio ($\gamma={c_p \over c_v}$) of ...
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0answers
87 views

The phlogiston theory [closed]

I have looked this theory up on google and found that the theory is that when metal is burnt calx (metal oxide) and phlogiston is created (metal --> calx + phlogiston). Then I found out that ...
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2answers
49 views

Why doesn't natural gas combustion release only one-sixth as much carbon dioxide as coal burning?

Burning hydrogen releases a little more energy than burning carbon, correct? And methane is CH4, but coal is mostly C, correct? So shouldn't burning pure carbon release five times the CO2 (Assuming ...
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2answers
132 views

Will mixing hydrogen and oxygen without a spark result in combustion? [duplicate]

I plan to do the electrolysis of dilute sulphuric acid. This will produce hydrogen gas and oxygen gas at the anodes. I do not plan to collect these gases, but to simply let it form and release into ...
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0answers
35 views

How do fuel/oxidizer combustion mechanics change when the constituents are supercritical?

The problem to solve is this: I want to create a heat generator [or heat absorber] that functions at atmospheric pressure to the pressure at the bottom of the sea. It will be used to drive a Stirling ...
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1answer
55 views

Complete Combustion of Inorganic, Hydrogen Containing Covalent Compounds in the Atmosphere

From what I've seen in alkanes, their complete combustion creates carbon dioxide, which has carbon in its highest possible oxidation state. I've been wondering what complete combustion would look ...

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