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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: JimJo on January 30, 2008, 02:05:24 AM

Title: Natural abundance problem.
Post by: JimJo on January 30, 2008, 02:05:24 AM

I need help finding the mass of Ag^109 to this problem.

There are two naturally occurring isotopes of silver having the natural abundances: Ag^107, 51.84%; Ag^109, 48.16%. The mass of Ag^107 is 106.905092 u. What is the mass of Ag^109 to 4 sig figs?

So far i got this,? (.5184)(106.905092u)= 55.4195997u. for the Ag^107 and I'm stuck...

*The ^107 and ^109 should be on the left side of the Ag, i didn't know how to show it on the left so i put in on the right.

Title: Re: Natural abundance problem.
Post by: Borek on January 30, 2008, 03:49:46 AM

If you know formula for weighted average you have everything needed, just solve for the ¹⁰⁹Ag mass - that's simple algebra.

Title: Re: Natural abundance problem.
Post by: AWK on January 30, 2008, 03:59:47 AM

Take a mean value for Ag from a periodic table.