How Many Moles Of Co2 And H2o Will Be Produced By Combustion Analysis Of 0.010 Mol Of Styrene?
Understanding the combustion of organic compounds like styrene is fundamental in chemistry, especially when quantifying the amounts of carbon dioxide (CO₂) and water (H₂O) produced during combustion. This article explores the process of determining the moles of CO₂ and H₂O generated from burning 0.010 mol of styrene, providing a comprehensive overview suitable for students, educators, and chemistry enthusiasts alike.
Introduction to Styrene and Its Combustion
Styrene, also known as vinylbenzene, is an aromatic hydrocarbon with the chemical formula C₈H₈. It is widely used in the production of plastics, resins, and rubber. Its combustion is a classic example used in organic chemistry to illustrate how hydrocarbons react with oxygen, producing carbon dioxide and water.
Chemical Formula of Styrene: C₈H₈
Molecular Structure: Styrene consists of a benzene ring attached to an ethenyl group (–CH=CH₂). Its aromatic nature influences its combustion behavior and the formation of combustion products.
General Combustion Reaction of Styrene
When styrene undergoes complete combustion in excess oxygen, it produces carbon dioxide and water:
\[ \text{C}8\text{H}8 + \text{O}2 \rightarrow \text{CO}2 + \text{H}_2\text{O} \]
However, to determine the exact amounts of CO₂ and H₂O produced, the balanced chemical equation must be established.
Balancing the Combustion Equation
Let's write the unbalanced combustion reaction:
\[ \text{C}8\text{H}8 + O2 \rightarrow CO2 + H_2O \]
Balance carbon atoms:
\[ \text{C}8\text{H}8 + O2 \rightarrow 8\, \text{CO}2 + H_2O \]
Balance hydrogen atoms:
\[ \text{C}8\text{H}8 + O2 \rightarrow 8\, \text{CO}2 + 4\, H_2O \]
Now, balance oxygen atoms:
On the right side, oxygen atoms are:
\[ 8 \times 2 = 16 \text{ (from CO}2) + 4 \times 1 = 4 \text{ (from H}2\text{O}) = 20 \]
Thus, total oxygen atoms needed:
\[ 20 \]
On the left side, oxygen molecules (O₂) contribute 2 oxygen atoms each:
\[ \text{Number of O}_2 \text{ molecules} = \frac{20}{2} = 10 \]
The balanced combustion reaction:
\[ \text{C}8\text{H}8 + 10\, O2 \rightarrow 8\, CO2 + 4\, H_2O \]
Calculating Moles of CO₂ and H₂O Produced
Given 0.010 mol of styrene, the goal is to find the moles of CO₂ and H₂O generated.
Step 1: Determine the molar ratios
From the balanced equation:
- 1 mol of styrene produces 8 mol of CO₂
- 1 mol of styrene produces 4 mol of H₂O
This ratio remains constant regardless of the amount of styrene burned.
Step 2: Apply the molar ratios to the given amount
For 0.010 mol of styrene:
- Moles of CO₂ produced:
\[
0.010\, \text{mol} \times \frac{8\, \text{mol CO}2}{1\, \text{mol styrene}} = 0.080\, \text{mol CO}2
\]
- Moles of H₂O produced:
\[
0.010\, \text{mol} \times \frac{4\, \text{mol H}2\text{O}}{1\, \text{mol styrene}} = 0.040\, \text{mol H}2\text{O}
\]
Summary:
| Product | Moles Produced |
|---------|----------------|
| CO₂ | 0.080 mol |
| H₂O | 0.040 mol |
Implications and Applications of These Calculations
Understanding the quantities of gases produced during combustion has practical significance in various fields:
- Environmental Chemistry: Quantifying CO₂ emissions helps assess carbon footprints and environmental impact.
- Industrial Processes: In manufacturing, knowing combustion efficiencies aids in optimizing fuel use and reducing waste.
- Analytical Chemistry: Combustion analysis serves as a method to determine the composition of unknown organic compounds.
Additional Factors to Consider
While the theoretical calculations provide ideal results, real-world combustion may involve incomplete reactions or side products due to impurities, temperature variations, or incomplete oxygen supply. Therefore, actual experimental values might slightly differ from theoretical predictions.
Complete vs. Incomplete Combustion
- Complete Combustion: Produces only CO₂ and H₂O, as detailed above.
- Incomplete Combustion: May generate CO, soot, or other hydrocarbons, leading to less predictable product quantities.
Practical Example: Calculating Gas Volumes at Standard Conditions
Suppose you want to know the volume of CO₂ and H₂O vapor produced at standard temperature and pressure (STP). Using the molar volume of gases at STP (~22.4 L/mol):
- Volume of CO₂:
\[
0.080\, \text{mol} \times 22.4\, \text{L/mol} = 1.792\, \text{L}
\]
- Volume of H₂O vapor:
\[
0.040\, \text{mol} \times 22.4\, \text{L/mol} = 0.896\, \text{L}
\]
These calculations are useful in laboratory settings where gas collection and measurement are involved.
Conclusion
In summary, when combusting 0.010 mol of styrene, approximately 0.080 mol of carbon dioxide and 0.040 mol of water vapor are produced under ideal, complete combustion conditions. This precise quantification is essential for environmental assessments, industrial applications, and analytical chemistry. Understanding the stoichiometry involved in combustion reactions enables chemists to predict product yields, optimize processes, and interpret experimental data accurately.
Key Takeaways
- The balanced combustion equation for styrene is: \(\text{C}8\text{H}8 + 10\, O2 \rightarrow 8\, CO2 + 4\, H_2O\).
- 0.010 mol of styrene produces 0.080 mol of CO₂ and 0.040 mol of H₂O.
- Gas volumes at STP can be calculated using molar volume, aiding practical laboratory measurements.
- Real-world factors can influence actual yields, so theoretical calculations serve as ideal benchmarks.
