SSCE HSC Chemistry Alcohols: Under conditions of low oxygen l

Under conditions of low oxygen levels, octane can undergo incomplete combustion according to the following chemical equation: $$ 2C_{8}H_{18}(l) + 17O_{2}(g) \rightarrow 6C(s) + 4CO_{2}(g) + 6H_{2}O(l) $$ (a) Explain the need to monitor this process - HSC - SSCE Chemistry - Question 25 - 2060 - Paper 1

Question 25

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Under conditions of low oxygen levels, octane can undergo incomplete combustion according to the following chemical equation: $$ 2C_{8}H_{18}(l) + 17O_{2}(g) \right... show full transcript

Worked Solution & Example Answer:Under conditions of low oxygen levels, octane can undergo incomplete combustion according to the following chemical equation: $$ 2C_{8}H_{18}(l) + 17O_{2}(g) \rightarrow 6C(s) + 4CO_{2}(g) + 6H_{2}O(l) $$ (a) Explain the need to monitor this process - HSC - SSCE Chemistry - Question 25 - 2060 - Paper 1

Step 1

Explain the need to monitor this process.

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Answer

Monitoring the incomplete combustion of octane is essential to reduce the release of harmful pollutants, such as carbon monoxide (CO) and soot (C(s)), into the atmosphere. These substances pose health risks and can contribute to environmental degradation. Additionally, monitoring helps maximize the efficiency of the combustion process by adjusting the oxygen input, ensuring that the combustion is as complete as possible, thereby minimizing waste materials and improving fuel economy.

Step 2

Calculate the mass of soot (C(s)) produced if 4.2 moles of octane are combusted in this way.

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Answer

First, we determine the number of moles of carbon produced from the combustion of octane:

From the balanced equation, 2 moles of octane produce 6 moles of carbon:

\text{Mole ratio: } \frac{6\text{ moles C}}{2\text{ moles C}_8H_{18}} = 3

Thus, 4.2 moles of octane will produce:

\text{Moles of C} = 3 \times 4.2 = 12.6 \text{ moles C}

Next, we calculate the mass of carbon using its molar mass (approximately 12.01 g/mol):

\text{Mass} = \text{moles} \times \text{molar mass} = 12.6 \text{ moles C} \times 12.01 \text{ g/mol}

Calculating the mass gives:

\text{Mass} \approx 151.33 \text{ g}

Therefore, the mass of soot produced is approximately 150 g, or more precisely, 1.5 × 10² g.

Explain the need to monitor this process.

Calculate the mass of soot (C(s)) produced if 4.2 moles of octane are combusted in this way.

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