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Stoichiometry - Engineering

Q1:

1 gm mole of methane (CH4) contains

A 6.02 x 1023 atoms of hydrogen.

B 4 gm atoms of hydrogen.

C 3.01 x 1023 molecules of methane.

D 3 gms of carbon.

ANS:B - 4 gm atoms of hydrogen.

  1. 1 gm mole of methane (CH4) contains 6.02 x 10^23 atoms of hydrogen.
    • This statement is incorrect. In 1 mole of methane (CH4), there is 1 mole of carbon atoms and 4 moles of hydrogen atoms. Avogadro's number (6.02 x 10^23) represents the number of entities (atoms, molecules, ions, etc.) in 1 mole of substance. So, in 1 mole of methane, there are 4 x 6.02 x 10^23 =
2.408 x 10^24 atoms of hydrogen.
  1. 4 gm atoms of hydrogen.
    • This statement is unclear. If it's intended to say that there are 4 grams of hydrogen atoms, we need more information. The number of hydrogen atoms in 4 grams of hydrogen can be calculated using Avogadro's number and the molar mass of hydrogen, which is approximately 1 gram per mole.
  2. 3.01 x 10^23 molecules of methane.
    • This statement is correct. Avogadro's number represents the number of entities in 1 mole of substance. So, 3.01 x 10^23 molecules of methane corresponds to 1 mole of methane.
  3. 3 gms of carbon.
    • This statement doesn't directly relate to the others. It simply states that there are 3 grams of carbon. To find the number of moles of carbon, we need to know the molar mass of carbon, which is approximately 12 grams per mole. Then we can use the formula:
    Number of moles=MassMolar massNumber of moles=Molar massMass​ Substituting the given mass: Number of moles=3 g12 g/mol=0.25 molNumber of moles=12 g/mol3 g​=0.25 mol