Final answer:
The molecular formula of cyclopropane is C₃H₆ and its molar mass is 42.775 g/mol.
Step-by-step explanation:
To find the molecular formula of cyclopropane, we need to determine its empirical formula and molar mass. Cyclopropane is composed of 85.7% carbon and 14.3% hydrogen by mass. Assuming 100 g of cyclopropane, we can convert the percentage of each element into grams: 85.7 g of carbon and 14.3 g of hydrogen.
Next, we need to calculate the moles of carbon and hydrogen. The molar mass of carbon is 12.01 g/mol and the molar mass of hydrogen is 1.01 g/mol.
We can now calculate the empirical formula of cyclopropane by dividing the moles of carbon and hydrogen by the smallest number of moles. In this case, the smallest number of moles is 1. This gives us the empirical formula CH₂.
To find the molar mass of cyclopropane, we can use the given information that it has a density of 1.71 g/L at 755 mmHg and 25°C.
Molar mass = (density * 22.4 L/mol * 273.15 K) / (PV)
Plugging in the values, we get:
Molar mass = (1.71 g/L * 22.4 L/mol * 273.15 K) / (755 mmHg * 25°C)
Molar mass = 42.775 g/mol
Therefore, the molecular formula of cyclopropane is C₃H₆ and its molar mass is 42.775 g/mol.