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Molar massChemistryHigh schoolabout 1:13

What is the molar mass of C12H22O11?: animated lesson

A narrated, step-by-step molar mass video lesson with captions. Final answer: M(C12H22O11) = 342.297 g/mol.

Video with a synthetic English voice and captions. Pick another language for subtitles in that language, or open the interactive version.

Video narrated by a synthetic voice (Piper TTS, en_US-ljspeech-high voice (LJ Speech dataset, public domain)); the steps come from our maths engine and the answer was checked independently. Download MP4 (0.5 MB) · Captions (WebVTT)

Steps on screen

  1. 1. The problem
    Worked example
    What is the molar mass of C12H22O11?
  2. 2. Steps, part 1
    1. C:12,H:22,O:11\text{C}: 12,\quad \text{H}: 22,\quad \text{O}: 11
      Count the atoms of each element
    2. C=12.011,H=1.008,O=15.999\text{C} = 12.011,\quad \text{H} = 1.008,\quad \text{O} = 15.999
      Look up each atomic weight (g/mol)
    3. 12×12.011=144.13222×1.008=22.17611×15.999=175.98912 \times 12.011 = 144.132 \\ 22 \times 1.008 = 22.176 \\ 11 \times 15.999 = 175.989
      Multiply each count by its atomic weight
    4. M=144.132+22.176+175.989=342.297 g/molM = 144.132 + 22.176 + 175.989 = 342.297\ \text{g/mol}
      Add the contributions
  3. 3. Steps, part 2
    1. %C=144.132342.297×100≈42.11%%H=22.176342.297×100≈6.48%%O=175.989342.297×100≈51.41%\%\text{C} = \frac{144.132}{342.297} \times 100 \approx 42.11\% \\ \%\text{H} = \frac{22.176}{342.297} \times 100 \approx 6.48\% \\ \%\text{O} = \frac{175.989}{342.297} \times 100 \approx 51.41\%
      Mass percent of each element
  4. 4. The answer
    M=342.297 g/molM = 342.297\ \text{g/mol}

    12×12.011 + 22×1.008 + 11×15.999 = 342.297 g/mol

  5. 5. Check
    • Percent composition adds to 100.00%.
    • Elements: carbon ×12, hydrogen ×22, oxygen ×11.

Transcript

The problem. Here is the problem: What is the molar mass of C12H22O11? Add the atomic weights of all 45 atoms in one formula unit of C12H22O11.

Steps, part 1. Count the atoms of each element. Subscripts multiply everything inside the brackets before them, and a hydrate coefficient multiplies the whole water (or other) unit. Look up each atomic weight (g/mol). IUPAC standard atomic weights (abridged, conventional values). Multiply each count by its atomic weight. Add the contributions.

Steps, part 2. Mass percent of each element.

The answer. So the answer is M(C12H22O11) equals 342.297 g/mol. The molar mass is the mass of one mole of formula units. It equals the sum of the atomic weights of every atom in the formula, and numerically matches the formula mass in daltons (u).

Check. Percent composition adds to 100.00 percent. Elements: carbon times 12, hydrogen times 22, oxygen times 11.

About molar mass

Add atomic masses to find the molar mass of a compound from its formula.

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What is the molar mass of C12H22O11?: Molar mass Lesson