Determine the molar mass of acetic acid, C3H4O2.

molar mass of C X 3 mol C =
molar mass of H X 4 mol H =
molar mass of O X 2 mol =
sum for total mass

The Correct Answer and Explanation is:

To determine the molar mass of acetic acid (C₃H₄O₂), we calculate the contributions from each type of atom in the formula:

Step-by-step calculation:

1. Carbon (C):

Molar mass of carbon (C) = 12.01 g/mol
Number of carbon atoms = 3
Contribution:
12.01 g/mol × 3 = 36.03 g/mol

2. Hydrogen (H):

Molar mass of hydrogen (H) = 1.008 g/mol
Number of hydrogen atoms = 4
Contribution:
1.008 g/mol × 4 = 4.032 g/mol

3. Oxygen (O):

Molar mass of oxygen (O) = 16.00 g/mol
Number of oxygen atoms = 2
Contribution:
16.00 g/mol × 2 = 32.00 g/mol

Total molar mass of C₃H₄O₂:

36.03 + 4.032 + 32.00 = 72.062 g/mol

Final Answer:

Molar mass of acetic acid (C₃H₄O₂) = 72.06 g/mol (rounded to 2 decimal places)

Explanation

The molar mass of a compound is the sum of the atomic masses of all the atoms present in its chemical formula. Each element has a unique atomic mass, typically expressed in grams per mole (g/mol), which represents the mass of one mole (6.022 × 10²³ particles) of that element. For molecular compounds like acetic acid (C₃H₄O₂), we calculate the molar mass by adding up the contributions from all atoms based on their quantities in the formula.

Acetic acid, commonly found in vinegar, contains 3 carbon atoms, 4 hydrogen atoms, and 2 oxygen atoms. First, the molar mass of each element is determined from the periodic table: carbon (12.01 g/mol), hydrogen (1.008 g/mol), and oxygen (16.00 g/mol). Then, these values are multiplied by the number of each type of atom in the molecule. Carbon contributes 36.03 g/mol (12.01 × 3), hydrogen contributes 4.032 g/mol (1.008 × 4), and oxygen contributes 32.00 g/mol (16.00 × 2).

By summing these contributions, we get the total molar mass: 36.03 + 4.032 + 32.00 = 72.062 g/mol. This value is critical in chemistry as it allows scientists to convert between mass and moles, enabling calculations in reactions, concentrations, and stoichiometry. For example, knowing the molar mass of acetic acid is essential when preparing solutions or analyzing its role in biochemical processes.

In conclusion, the accurate calculation of molar mass is foundational to quantitative chemistry and practical laboratory work.