Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    12
    ReputationRep:
    Our chemistry teacher recently explained us that it does so because sodium is less dense than water to which I fully agree but he added that if the sodium is a heavy enough chunk, it would sink -which got me confused - he said due to water molecules forming hydrogen bonds, they form a 'skin'which the heavier chunks can force through but smaller sodium pieces cannot. I personally think my chemistry teacher forgot physics. Can anyone clear my confusion? Thanks.
    Offline

    11
    ReputationRep:
    From what it sounds like, he's describing surface tension. A small piece of sodium isn't going to breach the large amount of surface tension, but a larger piece would because it has more mass.
    • Community Assistant
    • Study Helper
    Online

    15
    ReputationRep:
    Community Assistant
    Study Helper
    (Original post by thebrahmabull)
    Our chemistry teacher recently explained us that it does so because sodium is less dense than water to which I fully agree but he added that if the sodium is a heavy enough chunk, it would sink -which got me confused - he said due to water molecules forming hydrogen bonds, they form a 'skin'which the heavier chunks can force through but smaller sodium pieces cannot. I personally think my chemistry teacher forgot physics. Can anyone clear my confusion? Thanks.
    It's forming hydrogen gas (very light) whose bubbles are fastened to the sodium giving it lift ...

    However, it has almost the same density as water (a little less, 0.97 g cm-3), so you would expect it to float anyway.
    • Thread Starter
    Offline

    12
    ReputationRep:
    (Original post by charco)
    It's forming hydrogen gas (very light) whose bubbles are fastened to the sodium giving it lift ...

    However, it has almost the same density as water (a little less, 0.97 g cm-3), so you would expect it to float anyway.
    I see. But considering only density, the sodium should float irrespective of how heavy it is right?


    (Original post by GetOverHere)
    From what it sounds like, he's describing surface tension. A small piece of sodium isn't going to breach the large amount of surface tension, but a larger piece would because it has more mass.
    I understand the surface tension fact and agree that it would break with a heavier chunk however according to Archimedes'theorem, the weight of the water displaced by the sodium would be greater than the weight of the sodium since it has greater density. Which means upthrust on the sodium is greater than its weight ,which means it would float irrespective of its mass. So even if surface tension breaks, the heavier chunk of sodium should float right?
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?

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.