Question

What volume of carbon dioxide is produced at STP when 5 litres of propane is burnt completely according to the equation given below?
[ C_3H_8 + 5O_2 3CO_2 + 4H_2O ]

• A. 10 litres
• B. 15 litres
• C. 20 litres
• D. 25 litres

Hint:

As long as all reactants and products are gases at the same temperature and pressure, you can use the coefficients of the balanced equation directly as volume ratios!

Answer 1

The Correct Option is B

To solve this problem, first understand the chemical reaction involved and apply stoichiometry to find the volume of carbon dioxide (CO₂) produced when propane (C₃H₈) is completely burnt at Standard Temperature and Pressure (STP).

The balanced chemical equation for the complete combustion of propane is:

\(C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O\)

From the equation, we see that burning 1 mole of propane produces 3 moles of carbon dioxide. At STP, 1 mole of any gas occupies 22.4 liters.

1. According to the stoichiometry of the reaction, 1 volume of C₃H₈ produces 3 volumes of CO₂.
2. Given: 5 liters of C₃H₈ is burnt.
3. Using the ratio from the balanced equation: \(5 \text{ L of } C_3H_8 \times \frac{3 \text{ L of } CO_2}{1 \text{ L of } C_3H_8} = 15 \text{ L of } CO_2\)

Thus, when 5 liters of propane is burnt completely, 15 liters of carbon dioxide is produced at STP.

Therefore, the correct answer is: 15 litres.