Determining the Amount of Water Produced in the Combustion of Propane

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The combustion reaction of propane with oxygen is a common example in chemistry, which not only releases energy but also results in the formation of water. The reaction can be represented by the balanced equation:

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Balanced Equation for Propane Combustion

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C3H8 5O2 → 3CO2 4H2O

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This equation shows that one mole of propane reacts with five moles of oxygen to produce three moles of carbon dioxide and four moles of water. We can use this equation to determine the amount of water produced when a given amount of propane is combusted.

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Calculating the Moles of Water Produced from 25g of Propane

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Let's start with calculating the molar mass of propane (C3H8):

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1 mole of C3H8 3(12.011g/mol C) 8(1.008g/mol H) 44.097g/mol

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Now, determine the moles of propane in 25g:

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Moles of C3H8 mass of C3H8 (g) / molar mass of C3H8 (g/mol) 25 g / 44.097 g/mol ≈ 0.5669 mol

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Next, we need to find the number of moles of water produced. From the balanced equation, we know the mole ratio of C3H8 to H2O is 1:4. Therefore, 0.5669 moles of C3H8 will produce:

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0.5669 mol C3H8 × 4 mol H2O / 1 mol C3H8 ≈ 2.27 mol H2O

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Thus, approximately 2.3 moles of water (H2O) will be produced when 25g of propane reacts with oxygen.

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Further Calculations

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Let's consider a more complex scenario. If 4 moles of water are produced by 1 mole of C3H8, how many moles of C3H8 would produce 7.25 moles of water?

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moles of C3H8 7.25 mol H2O / 4 mol H2O / 1 mol C3H8 1.8125 mol C3H8

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Now, we can convert these moles of C3H8 into grams to see the amount of propane needed:

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mass of C3H8 moles of C3H8 × molar mass of C3H8 1.8125 mol × 44.097 g/mol ≈ 79.82 g C3H8

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This calculation shows that 79.82 grams of propane are needed to produce 7.25 moles of water.

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Summary

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Understanding the chemistry behind the combustion of propane and its reaction with oxygen to form water is crucial for various applications in chemistry and related fields. Using the balanced equation and stoichiometry principles, it's straightforward to calculate the amount of water produced from a given amount of propane. This process not only enhances our understanding of chemical reactions but also provides valuable insights for practical applications.

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References

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Petrucci, R. H., Harwood, W. S., Herring, F. G., Madura, J. D. (2017). General Chemistry: Principles and Modern Applications (10th ed.). Pearson.

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Primer on Stoichiometry (2019). The Chemistry Tutor. Retrieved from