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(a) Why does not the atomic mass of an e...

(a) Why does not the atomic mass of an element represent the actual mass of its atom?
(b) The atomic mass of an element is in fraction. What does it mean?
(c) Why is the value of Avogadros number `6.022 xx 10^(23)` and not any other value? (d Does one gram mole of a gas occupy 24.4 L under all conditions of temperature and pressure?

Text Solution

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(a) Atoms of diffterent elements are very Stmal in sze and their actual mass are extremely small. For example. the mass of an atom of hydrogen is `1.67 xx 10^(-27)kg`. To solve this problem, we consider the relative atomic masses of the elements. The relative atomic mas of hydrogen is u and its corresponding gram atomic mass is 1 .
If the atomic mass of an element is in fraction, this means that it exists in the form of isotopes.
(c )It represents the number of atoms one gram atom of an element or the number of molecules in divide the atomic mass of an clement by actual mass of its atoms, the `10^(23)`. Similarly, by dividing the molecular mass of a compound by the actual mass of its molecules, the same result is obtained.
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Knowledge Check

  • If a mole is defined to be 3 xx 10^(21) (instead of Avogadro's Number, 6 xx 10^(23) ). What would be the mass of one mole of Argon atoms? [Atomic of zinc, Find gram atoms of aluminium in given mixture?]

    A
    40 gm
    B
    200 gm
    C
    20 gm
    D
    8 gm
  • By Avogadro's law, V=kn If volume occupied by 1 mole of a gas at STP is 22.4 L, then what will be the value of k if we take 0.5 mole of gas under same condition of temperature and pressure

    A
    `22.4 L " mol "^(-1)`
    B
    `11.2 L " mol "^(-1)`
    C
    `44.8 L " mol"^(-1)`
    D
    `5.6 L" mol"^(-1)`
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