# How Many Molecules of co2, h2o, c3h8, and o2 Will be Present if the Reaction Goes to Completion?

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46 # How Many Molecules of co2, h2o, c3h8, and o2 Will be Present if the Reaction Goes to Completion

Chemistry defines a reaction as the process by which existing substances change and new ones emerge. Reactants in chemical reactions refer to substances that transform, while products refer to what results from that change. In this article, we’ll analyze one specific reaction between CO2, H2O, C3H8, and O2 and calculate its molecular composition if it completes successfully. Upon completing this particular reaction, we’ll have 1 molecule of C3H8, 0 molecules of O2, 6 molecules of CO2, and eight molecules of H2O.

## Explanation of the Reaction

A combustion reaction occurs when CO2, H2O, C3H8, and O2. Combustion reactions are exothermic – they release heat energy. For C3H8, commonly referred to as propane, the chemical equation for this reaction is as follows:

C3H8 + 5O2 = 3CO2 + 4H2O

This equation tells us that when propane is burned with oxygen, it forms three molecules of carbon dioxide (CO2) and four molecules of water (H2O). To know exactly how many molecules of each compound will remain at completion, stoichiometry calculations must be performed.

## Stoichiometry Calculations

Stoichiometry is the branch of chemistry that studies the quantitative relationships between reactants and products in chemical reactions. It allows us to calculate how much of each reactant is necessary to create a certain amount of product from a given amount of reactant.

Stoichiometry calculations require using the coefficients in a balanced chemical equation to calculate mole ratios between reactants and products. A mole is a unit of measurement in chemistry that represents an amount of substance with the same number of entities (atoms, molecules, ions, or other particles) as 12 grams of carbon-12. A mole ratio tells us how many moles of one substance must react with another certain number of moles.

Let’s use the balanced chemical equation for propane combustion to calculate how many molecules each compound will remain after completion.

First, we must convert the number of molecules of propane to moles. The molar mass of propane is 44.1 grams per mole, so if we have 1 mole, there are 44.1 grams.

Assuming we have 1 molecule of propane, we can use Avogadro’s number (6.02 x 10^23) to convert it to moles:

1 molecule C3H8 = 1/6.02 x 10^23 moles C3H8

Next, we use the mole ratio from the balanced equation to determine the number of moles of oxygen required to react with 1 mole of propane:

1 mole C3H8 reacts with 5 moles O2

Therefore, if we have 1/6.02 x 10^23 moles of propane, we need 5/6.02 x 10^23 moles of oxygen.

We repeat this process for carbon dioxide and water. The mole ratio tells us that 1 mole of propane reacts to form 3 moles of carbon dioxide and 4 moles of water:

1 mole C3H8 → 3 moles CO2

Therefore, if we have 1/6.02 x 10^23 moles of propane, we will form 3/6.02 x 10^23 moles of carbon dioxide and 4/6.02 x 10^23 moles of water. Finally, we can convert the number of moles to the number of molecules using Avogadro’s number:

1 mole CO2 = 6.02 x 10^23 molecules CO2 1 mole H2O = 6.02 x 10^23 molecules H2O

Now we can calculate the number of molecules of each compound that will be present if the reaction goes to completion:

• CO2: 1/6.02 x 10^23 moles of propane × 3 moles of CO2 per mole of propane × 6.02 x 10^23 molecules of CO2 per mole of CO2 = 1 molecule of CO2
• H2O: 1/6.02 x 10^23 moles of propane × 4 moles of H2O per mole of propane × 6.02 x 10^23 molecules of H2O per mole of H2O = 1.33 molecules of H2O
• C3H8: 1 molecule of C3H8
• O2: 5/6.02 x 10^23 moles of oxygen × 6.02 x 10^23 molecules of O2 per mole of O2 = 5 molecules of O2

## Discussion of Results

Our calculations indicate that if the combustion of propane proceeds to completion, there will be one molecule of carbon dioxide, 1.33 molecules of water, one molecule of propane, and five molecules of oxygen present. But it’s essential to remember that reactions sometimes go to completion; there may be limiting factors like insufficient reactants or unfavorable conditions which prevent them from proceeding entirely.

Interestingly, our stoichiometry calculations assumed a complete reaction, meaning all reactants would have been consumed to form products. Unfortunately, this may only sometimes be the case, and other factors can impact yield in certain situations.

## Conclusion

Stoichiometry is an invaluable tool for understanding the quantitative relationships between reactants and products in a chemical reaction. Using mole ratios from a balanced chemical equation, we can calculate how many molecules of each compound will be present if the reaction proceeds as expected. For instance, in the case of propane combustion, our calculations revealed one molecule of carbon dioxide, 1.33 molecules of water, one molecule of propane, and five molecules of oxygen would remain after completion. Nonetheless, keep in mind that reactions do not always go according to plan; other factors could also influence yield.