Calculate the molar mass of citric acid.
The correct answer and explanation is:
✅ Correct Answer:
The molar mass of citric acid (C₆H₈O₇) is approximately 192.12 g/mol.
🧪 Explanation (300 words):
Citric acid is an organic acid commonly found in citrus fruits like lemons and oranges. Its chemical formula is C₆H₈O₇, which means each molecule contains:
- 6 Carbon (C) atoms
- 8 Hydrogen (H) atoms
- 7 Oxygen (O) atoms
To calculate the molar mass, we multiply the number of atoms of each element by their atomic masses (from the periodic table) and then add them together:
Atomic masses (rounded to 2 decimal places):
- Carbon (C) = 12.01 g/mol
- Hydrogen (H) = 1.008 g/mol
- Oxygen (O) = 16.00 g/mol
Now multiply and sum:
- Carbon: 6 × 12.01 g/mol = 72.06 g/mol
- Hydrogen: 8 × 1.008 g/mol = 8.06 g/mol
- Oxygen: 7 × 16.00 g/mol = 112.00 g/mol
Now, add all the contributions together: 72.06+8.06+112.00=192.12 g/mol72.06 + 8.06 + 112.00 = \boxed{192.12\ \text{g/mol}}
📘 Why It Matters:
Understanding molar mass is essential in chemistry because it allows scientists to convert between the mass of a substance and the number of moles, which is a central concept in stoichiometry and chemical reactions.
In practical use, citric acid’s molar mass helps determine how much is needed in food preservation, pharmaceuticals, and cleaning agents. For example, if a recipe calls for 0.5 moles of citric acid, you can now calculate that you need: 0.5 mol×192.12 g/mol=96.06 grams0.5 \text{ mol} × 192.12 \text{ g/mol} = 96.06 \text{ grams}