Stoichiometry Chemistry Example 1

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Example 1

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How many grams of O2\text{O}_2 are needed to completely burn 16.016.0 g of CH4\text{CH}_4? (CH4+2O2โ†’CO2+2H2O\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O})

Solution

  1. 1
    Moles of CH4=16.016.04=0.998โ€‰molโ‰ˆ1.00โ€‰mol\text{CH}_4 = \frac{16.0}{16.04} = 0.998\,\text{mol} \approx 1.00\,\text{mol}.
  2. 2
    From the equation: 1 mol CH4\text{CH}_4 requires 2 mol O2\text{O}_2. So moles of O2=2ร—1.00=2.00โ€‰mol\text{O}_2 = 2 \times 1.00 = 2.00\,\text{mol}.
  3. 3
    Mass of O2=2.00ร—32.00=64.0โ€‰g\text{O}_2 = 2.00 \times 32.00 = 64.0\,\text{g}.

Answer

64.0โ€‰gย ofย O264.0\,\text{g of O}_2
Stoichiometry uses mole ratios from balanced equations to convert between amounts of reactants and products. The steps are: grams โ†’ moles โ†’ mole ratio โ†’ moles โ†’ grams.

About Stoichiometry

The branch of chemistry that uses balanced chemical equations and mole ratios to calculate the precise quantities of reactants consumed and products formed in chemical.

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