1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
sergij07 [2.7K]
3 years ago
13

What is not true about most combustion reactions?

Chemistry
1 answer:
vazorg [7]3 years ago
6 0
Combustion, or burning,[1] is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion in a fire produces a flame, and the heat produced can make combustion self-sustaining. Combustion is often a complicated sequence of elementary radical reactions. Solid fuels, such as wood and coal, first undergo endothermic pyrolysis to produce gaseous fuels whose combustion then supplies the heat required to produce more of them. Combustion is often hot enough that incandescent light in the form of either glowing or a flame is produced. A simple example can be seen in the combustion of hydrogen and oxygen into water vapor, a reaction commonly used to fuel rocket engines. This reaction releases 242 kJ/mol of heat and reduces the enthalpy accordingly (at constant temperature and pressure):

2H
2(g) + O
2(g) → 2 H2O(g)

Combustion of an organic fuel in air is always exothermic because the double bond in O2 is much weaker than other double bonds or pairs of single bonds, and therefore the formation of the stronger bonds in the combustion products CO2 and  H2O results in the release of energy.[2] The bond energies in the fuel play only a minor role, since they are similar to those in the combustion products; e.g., the sum of the bond energies of CH4 is nearly the same as that of CO2. The heat of combustion is approximately -418 kJ per mole of O2 used up in the combustion reaction, and can be estimated from the elemental composition of the fuel.[2]

Uncatalyzed combustion in air requires fairly high temperatures. Complete combustion is stoichiometric with respect to the fuel, where there is no remaining fuel, and ideally, no remaining oxidant. Thermodynamically, the chemical equilibrium of combustion in air is overwhelmingly on the side of the products. However, complete combustion is almost impossible to achieve, since the chemical equilibrium is not necessarily reached, or may contain unburnt products such as carbon monoxide, hydrogen and even carbon (sootor ash). Thus, the produced smoke is usually toxic and contains unburned or partially oxidized products. Any combustion at high temperatures in atmospheric air, which is 78 percent nitrogen, will also create small amounts of several nitrogen oxides, commonly referred to as NOx, since the combustion of nitrogen is thermodynamically favored at high, but not low temperatures. Since combustion is rarely clean, flue gas cleaning or catalytic converters may be required by law.

You might be interested in
A fog over a lake. what two changes of state must occur to produce the fog? do the water molecules absorb or release energy duri
Zolol [24]
The water from the lake must first evaporate from the liquid state to the gaseous state and then condense in the air to form vapors.
The water molecules absorb energy while evaporating and release it when condensing. Their motion gets faster when they are evaporating and slows back down upon condensation.
3 0
3 years ago
Read 2 more answers
The Same force is applied to a 300 kg go kart and 100 kg wagon at the beginning of the race. Which time is true about their acce
murzikaleks [220]

Answer: Well!

Explanation: I was going to answer D but fverdell82156 got to it first! So I have to agree with him! It is D!

3 0
3 years ago
Several properties of water are shown. Classify each property as a physical property or a chemical property.
34kurt

Chemical property:

  • Can be split into hydrogen and oxygen
  • Reacts with certain metals

Physical property:

  • Is liquid at room temperature
  • Has a density of 1.0 g/cm³
7 0
2 years ago
The EPA scientist measures the pH level in one area of a river to be lower than normal and writes that a pollutant must have bee
shutvik [7]
Its an example of inference. 
4 0
3 years ago
Read 2 more answers
How is kinetic energy of particles and temperature related
Rufina [12.5K]

Answer:

The higher the temperature, the faster the particles move, the lower the temperature, the slower.

4 0
3 years ago
Other questions:
  • An acidic substance
    13·2 answers
  • Sedimentary rocks form
    9·1 answer
  • What does a plant produce during photosynthesis? A. Oxygen and glucose B. Carbohydrates and carbon C. Carbon, oxygen, and hydrog
    5·1 answer
  • The hydrogen ion concentration of a vinegar solution is 0.00010 m. how is this concentration written in scientific notation?
    10·2 answers
  • When optically active (S)-2-methylcyclopentanone is treated with aqueous base, the compound loses its optical activity. Explain
    9·1 answer
  • How do I find percent mass composition
    9·1 answer
  • A gravel can be broken down into different kinds of substances by physical processes. No chemical reactions are needed to separa
    9·2 answers
  • !!!PLEASE HELP!!!!
    13·1 answer
  • A radioactive nucleus emits a beta particle, then the parent and daughter nuclei are
    10·2 answers
  • Which statement explains how the charges on objects determine the electric force between them?(1 point)
    10·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!