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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: pinkdiamondgail on February 10, 2009, 02:19:05 PM

Title: Calculating Atomic Mass(Homework please help)
Post by: pinkdiamondgail on February 10, 2009, 02:19:05 PM

 ???

Can somebody help me please I think I have the problem right but I am not sure I just need to see if I have these two problems right??

Calculate the atomic mass of bromine. the two isotopes of bromine have atomic masses and relative abundance of 78.92 amu(50.69%) and 80.92 amu (49.31%)





The element copper has natural occuriing istopes with mass numbers of 63 and 65. The relative abundance and atomic  masses are 69.2% for mass=62.93amu, and 30.8% for mass=64.93amu. Calculate the average atomic mass of copper.

Title: Re: Calculating Atomic Mass(Homework please help)
Post by: fyodor.pav on February 10, 2009, 02:30:14 PM

I'm by no means an expert, but I'm 99% sure that you just multiply the AMUs by their respective abundances and add, so...

78.92 amu * .5069 + 80.92 amu * .4931 = 79.91 amu

Title: Re: Calculating Atomic Mass(Homework please help)
Post by: Ak on February 10, 2009, 11:13:44 PM

yeah thats right

Title: Re: Calculating Atomic Mass(Homework please help)
Post by: pinkdiamondgail on February 10, 2009, 11:18:58 PM

Thanks guys that's what I had I just wanted to be sure  ;D