Anytime anything burns in the usual sense , it is a combustion reaction. Combustion reactions are almost always exothermic i. When organic molecules combust the reaction products are carbon dioxide and water as well as heat.
In order for a fire to take place there are 3 main ingredients that must be present: Oxygen, Heat and Fuel. In chemistry we call the type of reaction that produces fire a combustion reaction. Combustion reactions are common and very important. Combustion means burning, usually in oxygen but sometimes with other oxidants such as fluorine. A combustion reaction happens quickly, producing heat, and usually light and fire. Any substance which can burn leads to combustion; while respiration uses glucose to give pyurvate and the to carbon dioxide.
Calculate moles of An exothermic reaction is one in which the reactants. The addition of one of the reactants in a reaction at equilibrium. If in a reaction one reactant is reduced and other is oxidised, what is name of such a reaction? Calculate t In one reaction common salt and water are produced. Guess the reactants. Minimum amount of energy that must be required for the collision between reactant molecules in a rea In a combustion reaction in the air, oxygen is the limiting reactant.
Oxygen is p We noted in the Introduction that we have generally found that variables such as amount of instruction, course instructor, and time of day do not seem to affect student performance on the kinds of conceptual questions we often pose Heron, b, However, we did notice in this study that students who received paired questions e. Although a detailed statistical calculation of the variance attributable to the presence or absence of both questions is beyond the scope of this paper, we note that the presence of both questions may have enhanced student performance.
If this is the case, it may artificially diminish the prevalence of some of the response patterns reported in Table 6. More data — and a more detailed analysis — is necessary to separate this effect from that of other possibly confounding variables. Our research adds to the existing literature in two significant ways. First, we found that adults in our population often argue that oxygen is used by or required for combustion, a commonly-cited result in the literature on children's ideas about burning Schollum and Happs, ; Driver, ; Meheut et al.
Second, to our knowledge, our finding that large percentages of introductory and advanced introductory chemistry students justify their answers with a combustion rule that is often inconsistent with conservation principles has not been reported elsewhere. However, it is consistent with recent research Talanquer, ; Taber, ; Taber and Bricheno, ; Cooper et al. The research described in this paper has a number of implications for instruction and curriculum development.
In particular, instructors and curriculum developers can use the patterns in student reasoning we describe to anticipate where students might struggle as they learn about combustion and to design instructional materials that seek to specifically address student difficulties. For example, on the basis of our research, we recommend that instruction on combustion should both: 1 focus on why carbon dioxide and water are produced during the combustion of hydrocarbons i.
It is important to note that the incorrect reasoning patterns we identified persist beyond instruction and arose in multiple contexts. The experience of the Physics Education Group at the UW has been that standard lecture instruction is often insufficient to address these types of difficulties and that instead students must go through the reasoning required to develop and apply the ideas themselves. In addition, we suspect that students' tendency to use inappropriate rules is not limited to the context of combustion.
Instead, we speculate that this is representative of a broader phenomenon in which students treat chemistry learning as the memorization and rote application of facts and formulas rather than as seeking to understand and explain chemical phenomena.
This has implications for all of chemistry learning. Not only does it suggest that we should pay attention to and seek to address the incorrect formulation and application of specific rules; we should also seek to foster an epistemologically and metacognitively robust stance toward learning chemistry, as making sense of chemical phenomena using general models and principles.
Finally, the results of this investigation have implications for inquiry into student understanding. The application of the specific combustion rules reported here is only problematic in the context of non-hydrocarbon combustion; in all situations in which hydrocarbons are burned in the presence of oxygen, carbon dioxide and water vapor are produced. Thus, students' misunderstandings may be masked by exam or other research questions such as the burning candle question posed in the context of hydrocarbon combustion.
Instructors and researchers may need to ask questions in multiple contexts in order to understand student thinking.
You cannot burn Iron filings and get copper oxide. It is not possible to generate, in the case of reaction b , CO 2 molecules without the presence of carbon atoms in the first place. If one argues that carbon is present in the air and is utilized in the reaction, then it must be included in the reactant side to make the equation valid. Also, since beryllium powder is burning, it should produce CO 2. Since it did not say that carbon dioxide and water are the ONLY products of the reaction, it is possible that any one of the 4 choices could have been what was burned.
Wood is also an applicable answer because it gives off steam and carbon dioxide, it may not be a hydrocarbon though as far as my knowledge goes. DOI: Received 28th April , Accepted 31st July Abstract On the basis of responses to written questions administered to more than one thousand introductory chemistry students, we claim that students often rotely apply memorized combustion rules instead of reasoning based on explanatory models for what happens at the molecular level during chemical reactions.
All rights reserved. The specific answer choices in this question were based on the most common student responses to the original beryllium oxide question Fig. Table 1 Populations that received each written question. Table 2 Percentages of students who chose each product in response to the beryllium oxide question. Table 3 Percentages of students who selected each chemical equation in response to the symbolic beryllium oxide question.
Table 4 Percentages of students who chose each reactant in response to the unknown chemical question. We can think of several reasons that this may be the case: 1 Students may have missed our request that they select all possible reactants. Table 5 Percentages of students who indicated changes in amounts of oxygen, carbon dioxide, and water vapor in response to the burning candle question.
Table 6 Percentages of students who used each rule in the beryllium oxide, symbolic beryllium oxide, unknown chemical, and burning candle contexts. Many students who chose answer choices a , b , and d — all consistent with the use of a combustion rule — gave no reasoning.
Thus, we hypothesize that the percentages of students using a combustion rule, as well as the percentages of students who provided explicit conservation reasoning, are underestimates.
The products can only have whatever is in the reactant so beryllium oxide would be the only possible product from the list. Burning something involves adding oxygen so c is best fit, and it's also balanced. Therefore, less O 2 will be in the air over time. This is because water and carbon dioxide are made up of carbon, hydrogen, and oxygen.
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