Nivedha posted an Question
October 15, 2020 • 01:56 am 30 points
  • CSIR NET
  • Chemical Sciences

An fcc lattice has lattice parameter a = 400 pm. calculate the molar volume of lattice including all empty space: (a) 10.8 ml (b) 96 ml (c) 8.6 ml (d) 9.6 ml

An fcc lattice has lattice parameter a = 400 pm. Calculate the molar volume of lattice including all empty space: (a) 10.8 ml (b) 96 ml (c) 8.6 ml (d) 9.6 ml

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  • comment-profile-img>
    Amit kumar nayak

    Hello dear... Listen if our unit cell would have contain 1 atom then we would have multiplied simply avogadro no... but our unit cell contain 4 atom... so we need to calculate for 1 atom first so we divided by 4...then we multiplied it with avogadro no

  • Nivedha

    sir, may i know why are we dividing the value 38.4 by 4? what is 4 mentioned in the answer?

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    for volume of 1 mole lattice we take here Na/4 × Volume of one unit cell... as Z=4 per unit cell for fcc lattice

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    now got this or any doubt?

    eduncle-logo-app

    yes sir. i understood. thank you.

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    😊👍

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    effective no of atoms for FCC/CCP(z)= 4

  • comment-profile-img>
    Dinesh khalmaniya 1

    option D

    cropped5671239891582844870.jpg
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    because we have to calculate molar volume of whole unit cell. given 38.4 cm3 is the volume of whole crystal which contains Na atoms.

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    4 atoms /unit cell makes a unit cell of FCC so we divide it by 4

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    got it ?

  • comment-profile-img>
    Priyanshu kumar best-answer

    option D

    cropped1428334993393679683.jpg
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    sir, why is 38.4 value being divided by 4? can you please explain?

    eduncle-logo-app

    fcc atom Z=4 per unit cell so for molar volume we divide by 4

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    now got it?

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