Calculate the molar mass of C3H8 (Propane) and round to 4 significant figures
Calculate the molar mass of C3H8 (Propane) and round to 4 significant figures
The Correct Answer and Explanation is:
Molar Mass of C₃H₈ (Propane)
To calculate the molar mass of propane (C₃H₈), we sum the molar masses of all the atoms in the molecular formula.
Step-by-Step Calculation:
- Carbon (C): 12.01 g/mol
3×12.01=36.03 g/mol3 \times 12.01 = 36.03 \, \text{g/mol} - Hydrogen (H): 1.008 g/mol
8×1.008=8.064 g/mol8 \times 1.008 = 8.064 \, \text{g/mol}
Total molar mass = 36.03 + 8.064 = 44.09 g/mol
➡️ Answer (rounded to 4 significant figures): 44.09 g/mol
Explanation
The molar mass of a compound is the mass of one mole of its molecules, expressed in grams per mole (g/mol). To determine this value, we use the atomic masses of the elements from the periodic table and multiply each by the number of atoms of that element in the compound.
In the case of propane (C₃H₈), the molecular formula tells us that each molecule is made of 3 carbon atoms and 8 hydrogen atoms. From the periodic table, the atomic mass of carbon (C) is approximately 12.01 g/mol, and that of hydrogen (H) is about 1.008 g/mol.
By multiplying the number of atoms of each element by their respective atomic masses and summing the results, we get the molar mass of propane:
- Carbon: 3×12.01=36.033 \times 12.01 = 36.03 g/mol
- Hydrogen: 8×1.008=8.0648 \times 1.008 = 8.064 g/mol
- Total: 36.03+8.064=44.09436.03 + 8.064 = 44.094 g/mol
This value is then rounded to four significant figures, a standard practice in scientific reporting to reflect appropriate precision. Thus, the molar mass is 44.09 g/mol.
Understanding molar mass is essential in chemistry because it allows for conversions between the mass of a substance and the amount in moles—an important concept in stoichiometry, chemical reactions, and solution concentrations. For instance, if you had 88.18 grams of propane, you could divide by its molar mass (44.09 g/mol) to determine you have 2.000 moles of propane. This precise relationship supports accurate measurements in laboratory and industrial chemical processes.
