What mass of hydrogen gas would be required to completely react with 8 g of oxygen gas to form water?

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AAI Junior Assistant (Fire Service) Official Paper (Held On: 15 Nov, 2022 Shift 2)
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  1. 8 g
  2. 2g
  3. 1 g
  4. 4 g

Answer (Detailed Solution Below)

Option 3 : 1 g
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Detailed Solution

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The correct answer is 1 g.

Key Points

  • The balanced chemical equation for the formation of water is: 2H2 + O2 → 2H2O.
  • The molar mass of hydrogen (H2) is approximately 2 g/mol.
  • The molar mass of oxygen (O2) is approximately 32 g/mol.
  • According to the equation, 1 mole (32 g) of O2 reacts with 2 moles (4 g) of H2.
  • Therefore, 8 g of O2 will react with 1 g of H2 to form water.

Additional Information

  • Stoichiometry
    • It is the calculation of reactants and products in chemical reactions.
    • Based on the law of conservation of mass, which states that mass is neither created nor destroyed in a chemical reaction.
  • Molar Mass
    • The mass of one mole of a substance, expressed in grams per mole (g/mol).
    • Calculated by summing the atomic masses of all atoms in a molecule.
  • Balanced Chemical Equation
    • A chemical equation with equal numbers of atoms for each element in the reactants and products.
    • Ensures the law of conservation of mass is obeyed.
  • Law of Conservation of Mass
    • States that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations.
    • The mass of the products in a chemical reaction must equal the mass of the reactants.
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