what is the mass percentage of carbon in the methonal molecule?
The correct answer and explanation is:
Correct Answer:
The mass percentage of carbon in a methanol (CH₃OH) molecule is 37.5%.
Explanation (300 words):
To calculate the mass percentage of carbon in methanol (CH₃OH), we need to follow these steps:
Step 1: Determine the molecular formula
Methanol has the chemical formula CH₃OH. This means it contains:
- 1 carbon (C) atom
- 4 hydrogen (H) atoms (3 from CH₃ and 1 from OH)
- 1 oxygen (O) atom
Step 2: Find the atomic masses
From the periodic table:
- Carbon (C) = 12.01 g/mol
- Hydrogen (H) = 1.008 g/mol
- Oxygen (O) = 16.00 g/mol
Step 3: Calculate the molar mass of methanol
Add the masses of all the atoms in the molecule: Molar mass of CH₃OH=(1×12.01)+(4×1.008)+(1×16.00)=12.01+4.032+16.00=32.042 g/mol\text{Molar mass of CH₃OH} = (1 \times 12.01) + (4 \times 1.008) + (1 \times 16.00) \\ = 12.01 + 4.032 + 16.00 = 32.042 \, \text{g/mol}
Step 4: Calculate the mass percentage of carbon
Use the formula: \text{Mass % of Carbon} = \left( \frac{\text{Mass of C}}{\text{Molar Mass of CH₃OH}} \right) \times 100 \\ = \left( \frac{12.01}{32.042} \right) \times 100 \approx 37.5\%
Why This Matters:
Understanding mass percentage composition is crucial in chemistry because it helps determine how much of a given element is present in a compound. This concept is vital for stoichiometry, chemical analysis, and creating balanced reactions in lab or industrial settings. In the case of methanol—a simple alcohol used as fuel, solvent, and antifreeze—knowing its carbon content is essential in contexts like combustion reactions and carbon emission studies.
So, methanol consists of approximately 37.5% carbon by mass, making carbon a major but not dominant component of its molecular structure.