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 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. $${H_2}{O_2} \to {H_2}O + 0.5{O_2}$$ At 1200K, $${h_{{H_2}O}}^{1200K} - {...
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why is energy released when a chemical bonds is formed? [closed]

why is energy released when a chemical bonds is formed?
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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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If you ignite a gas stream of methane and carbon dioxide, what is the exhaust? [closed]

I know from my own research that some years after a landfill is closed, the gas emitted settles into a mixture consisting of methane and carbon dioxide in roughly 50/50 proportion (not sure if that's ...
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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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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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50 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
149 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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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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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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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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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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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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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
53 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
49 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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79 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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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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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
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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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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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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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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
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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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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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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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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
59 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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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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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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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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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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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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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
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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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About Smoke Grenades and Sugar Rockets

The most common formula for smoke grenades and sugar rocket fuel is $60\%\ \ce{KNO3}$ (potassium nitrate) and $40\%\ \ce{C12H22O11}$ (sugar). This is a 3:2 ratio, but I've also seen 2:1 and 5:3 with ...
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Rate law of the reaction of propane with oxygen

In class, I have a demonstration where I light a bubble filled with propane. As I add oxygen, the bubbles combust faster and more quickly. I have already balanced out the chemical reaction like so: $$...
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How to capture the gas produced by combusting alcohols

I am burning various alcohols and am attempting to capture the carbon dioxide produced. I could burn the alcohols in a conical flask with a cork on the top, with a tube directing the gas into a gas ...
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2answers
157 views

Complete combustion of mixtures

I am working on my scholarship exam practice (around high school and first year university level). I could actually solve the problem below but my solution is pretty time consuming. It would be ...
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1answer
282 views

Heat and work of glucose combustion

$$\ce{C6H12O6(s) + 6 O2(g) -> 6 CO2(g) + 6 H2O(g)}$$ When looking at glucose combustion I found that the change in Gibbs free energy is greater than the change in enthalpy. If we assume the process ...
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291 views

Based on their respective number of degrees of freedom, what's the most efficient fuel; hydrogen or gasoline?

The reaction of octane's combustion is: $$\ce{2 C8H18 + 25 O2 -> 18 H2O + 16 CO2}$$ I am asked for computing the number of degrees of freedom of the octane given that its specific heat is $\pu{...
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1answer
345 views

Redox Combustion Reactions

Consider a combustion reaction like the complete combustion of ethane. Here is what I have for the complete combustion as well as the oxidation and reduction: $$\ce{\overset{-3}{C}_2\overset{+1}{H}_6 ...
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When a candle burns, why does the top of wick glow if bottom of flame is hottest?

Totally an elementary question. Staring at a candle, it appears that the bottom of the wick is dark whereas the top glows. However the bottom of the flame (the blue) is the hottest. Is the reason ...
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46 views

Hydrogen peroxide and carbon as hybrid rocket propellant?

I was thinking that a hybrid rocket could be made using hydrogen peroxide and activated charcoal or some other carbon source. Step 1: Decompose hydrogen peroxide to steam and oxygen, as in a ...
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Does oxyhydrogen require the presence of water to ignite?

I recently read a short story (fiction) where a major plot element was based on the expectation that a mixture of oxygen and hydrogen will not ignite unless some amount of water is present to get the ...
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1answer
1k views

Why is the auto ignition temperature of petrol higher than that of diesel? [closed]

I can't find any reasonable explanation please help.
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2answers
339 views

Percent hydrogen and carbon [closed]

A 1 g sample of an organic compound was burned in a combustion analyzer and yielded 1.42 g carbon dioxide and 0.872 g of water. Calculate the percent carbon and hydrogen in the sample. From the ...

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