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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: dipndots on September 20, 2007, 11:32:39 PM

Title: Atomic mass of an unknown element
Post by: dipndots on September 20, 2007, 11:32:39 PM

So heres the question:

It is found that 0.119g of element Z contains 1.50 x 10^21 atoms. The atomic mass of Z is..

Title: Re: Atomic mass of an unknown element
Post by: Yggdrasil on September 21, 2007, 12:40:38 AM

Please read the Forum Rules (http://www.chemicalforums.com/index.php?page=forumrules).  You should that you've at least attempted to answer the problem before we will help you.

Title: Re: Atomic mass of an unknown element
Post by: Padfoot on September 21, 2007, 04:26:21 AM

What is atomic mass?

Title: Re: Atomic mass of an unknown element
Post by: dieded on September 22, 2007, 06:30:21 AM

Remember the Avogadro constant  (http://en.wikipedia.org/wiki/Avogadro_constant).

Approximately 6 * 10^23 atoms of Z will make up the atomic mass of Z.

And Yggdrasil you should at least at least help out dipndots a bit.

Title: Re: Atomic mass of an unknown element
Post by: Borek on September 22, 2007, 07:24:30 AM

Mass of 5 marbles is found to be 3 g, what is a mass of a dozen?

Title: Re: Atomic mass of an unknown element
Post by: kiet on September 22, 2007, 09:33:12 AM

  1 mol atoms has 6.023 x 10^23 atoms
We know that  n =(the amount of atoms)/(6.023x10^23)
               => n = (1.50x10^21)/(6.023X10^23) =0.00249 (mol)
   and m=nxM => M=m/n=0.119/0.00249=47.79
So the atomic mass of the element Z is approximately 47.8
Z is Titanium.

Title: Re: Atomic mass of an unknown element
Post by: dipndots on September 27, 2007, 09:44:04 PM

I got it. omg thanks. Seems simple when u explained it