Turn on thread page Beta
    • Thread Starter
    Offline

    13
    ReputationRep:
    Admittedly even at A-level I'm still a little shaky on the definition of a mole. I understand that a mole of a substance contains 6.02 x 10^23 grams, but with that knowledge I can't seem to get the right answer to this question:

    What is the number of atoms in 2.8 grams of ethene?
    Data given: Molar mass of C2H4 is 28g mol-1, Avogadro constant is 6.0 x 10^23

    My working is:

    28 g of ethene = 6.0 x 10^23 atoms
    therefore 2.8g of ethene = 6.0 x10^22 atoms

    The correct answer is 3.6 x 10^23 grams. I know that there are 6 atoms in an ethene molecule but how do I use that to arrive at the correct answer? Does one mole of ethene not contain 6.0 x10^23 atoms?

    Thanks
    Offline

    15
    ReputationRep:
    As you said, there are 6 atoms in an ethene molecule, so you have to alter your answer to fit. You were on the right lines, so you just need to do the last step. An atom refers to the smallest particle of a chemical ELEMENT that can exist.
    Online

    20
    ReputationRep:
    (Original post by Gabzinc)
    Admittedly even at A-level I'm still a little shaky on the definition of a mole. I understand that a mole of a substance contains 6.02 x 10^23 grams, but with that knowledge I can't seem to get the right answer to this question:

    What is the number of atoms in 2.8 grams of ethene?
    Data given: Molar mass of C2H4 is 28g mol-1, Avogadro constant is 6.0 x 10^23

    My working is:

    28 g of ethene = 6.0 x 10^23 atoms
    therefore 2.8g of ethene = 6.0 x10^22 atoms

    The correct answer is 3.6 x 10^23 grams. I know that there are 6 atoms in an ethene molecule but how do I use that to arrive at the correct answer? Does one mole of ethene not contain 6.0 x10^23 atoms?

    Thanks
    One mole of ethene contains 6.0x10^23 molecules, not atoms. So 2.8g is 0.1 moles or 6.0x10^22 molecules. Then multiply that by 6 because there are 6 atoms in an ethene molecule.
    • Thread Starter
    Offline

    13
    ReputationRep:
    (Original post by TheMindGarage)
    One mole of ethene contains 6.0x10^23 molecules, not atoms. So 2.8g is 0.1 moles or 6.0x10^22 molecules. Then multiply that by 6 because there are 6 atoms in an ethene molecule.
    Oooh!
    OoOoOoOh i see now, thanks!
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: November 11, 2017
Poll
Do you think parents should charge rent?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.