Moderate

If 30 mL of H2 and 20 mL of O2 react to form water, what is left at the end of the reaction?

Correct answer: D. 5 mL of O2

  • A. 10 mL of H2
  • B. 5 mL of H2
  • C. 10 mL of O2
  • D. 5 mL of O2

Explanation

Step 1:Volume of H2 = 30 ml volume of O2 = 20 ml reaction between H2 and O2 to form water is as follows:H2+12O2⟶H2O 30mL 15 mL reactedStep 2:According to the equation:1ml of H2 reacts with 1/2 mL of O2 to form 1 mL of H2O.So, 30 mL of H2 will react with 15 mL of O2 to form 30 mL of water.Step 3: Therefore, O2 is present in excess.Volume of O2 left = 20−15=5mLThus, 5 mL of O2 will be left behind and H2 is the limiting reagent.

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About Fundamental Concepts of Chemistry

Mole calculations connect mass, number of particles and Avogadro's number, while balanced equations provide the mole ratios used in stoichiometry. Questions cover limiting and excess reactants, theoretical yield and percentage yield, including identifying which reactant is consumed first and comparing the actual product with the maximum possible product.

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