Question

14g of cyclopropane burnt completely in excess oxygen. The number of moles of water formed is:

• A. 1.4 moles
• B. 2.8 moles
• C. 2.0 moles
• D. 1.0 mole
• E. 4 moles

Hint:

In stoichiometry problems, always ensure to start with a balanced chemical equation and use it to determine the relationships between reactants and products.

Answer 1

The Correct Option is D

The combustion of cyclopropane (\(C_3H_6\)) can be represented by the following balanced chemical equation: \[ C_3H_6 + 4.5O_2 \rightarrow 3CO_2 + 3H_2O \] This equation indicates that each mole of cyclopropane produces 3 moles of water (\(H_2O\)). First, calculate the molar mass of cyclopropane: \[ Molar \, mass \, of \, C_3H_6 = 3 \times 12.01 \, (C) + 6 \times 1.008 \, (H) = 36.03 + 6.048 = 42.078 \, g/mol \] Now, calculate the number of moles of cyclopropane: \[ Moles \, of \, C_3H_6 = \frac{14 \, g}{42.078 \, g/mol} = 0.333 \, moles \] Using the stoichiometry of the reaction, the moles of water produced are three times the moles of cyclopropane: \[ Moles \, of \, H_2O = 3 \times 0.333 \, moles = 1.0 \, mole \] Thus, the correct answer is option (D), 1.0 mole.