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Physics question

blue powderblue powder Registered User regular
edited November 2007 in Help / Advice Forum
Just to clarify, this is a question I'm doing from a past exam paper in preparation for an up coming exam. So I'm not asking you guys to do my homework haha.

The question is: "What is the average distance between argon atoms in a sample of argon gas at standard temperature and pressure (STP = 0C and 1 atm)?" At the STP, the molar volume of an ideal gas is 22.4 L. The atomic mass of argon is 40.0 amu.

So from this my working out is as follows:

22.4L/40amu = 0.56 * 6.02x10^23

= (i'm not sure how to get that cubed divide sign up-ask me if you don't know what i mean, sorry!) 3.37x10^23

= 69597692.26

= 1/69597692.26

= 1.43x10^-8 m


I'm not sure I have my units correct... This is just a weird way for me to approach a question like that as I'm used to doing it with a solid and using the density. Thanks in advance!

blue powder on

Posts

  • Al_watAl_wat Registered User regular
    edited November 2007
    List the equations you have at your disposal, in terms of their base units.

    Al_wat on
  • VeritasVRVeritasVR Registered User regular
    edited November 2007
    For starters, to remove confusion and complexity, use Significant Figures to reduce the number of digits you have to deal with. For example, you shouldn't really ever have to use your 10 digit number there without rounding to the nearest 3 (like your other numbers).

    69597692.26 should be 6.96 * 10^7. Makes them a lot easier to deal with because the exactness of the numbers you round are almost never necessary.

    VeritasVR on
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    Let 'em eat fucking pineapples!
  • Iceman.USAFIceman.USAF Major East CoastRegistered User regular
    edited November 2007
    On the other hand, I only round at the end. What I write on paper might only be 3 places, but I let my calculator carry everything. Just thought I'd toss that in.

    Also, it seems ok. I never liked that particular problem, however.

    Iceman.USAF on
  • PeekingDuckPeekingDuck __BANNED USERS regular
    edited November 2007
    Physics is easier if you don't use numbers. Beyond that, list what you have and the equations you know. Then it becomes a simple known, unknown. Just a general tip for your upcoming exam!

    PeekingDuck on
  • DemerdarDemerdar Registered User regular
    edited November 2007
    Another little tip: units. Always always show your units. If they aren't coming out, you're messing something up.

    Demerdar on
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  • corcorigancorcorigan Registered User regular
    edited November 2007
    Demerdar wrote: »
    Another little tip: units. Always always show your units. If they aren't coming out, you're messing something up.

    I got an A in a level chemistry simply by always using units (plus a load of pointless memorising, but you don't need so much of that for physics).

    corcorigan on
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