According to scientists, the mercury concentration in some tuna is #"1.4 ppm"#. How many mercury atoms would be found in #"100 g"# of this tuna?

1 Answer
Truong-Son N.
Oct 19, 2017

According to who now? I don't really want to trust any unnamed scientists...

Regardless, I got #4.20 xx 10^17# mercury atoms.

If we assume the mercury concentration in tuna is #"1.4 ppm"#, then we could write this as:

#"1.4 mg Hg"/"kg tuna"#

And so, if we have #"100 g"# of tuna...

#100 cancel"g tuna" xx cancel"1 kg"/(1000 cancel"g") xx "1.4 mg Hg"/(cancel"kg tuna")#

#=# #"0.14 mg Hg"# #=# #"0.00014 g Hg"#

And every mercury atom has a molar mass of #"200.59 g/mol"#...

#0.00014 cancel"g Hg" xx cancel"1 mol Hg"/(200.59 cancel"g Hg") xx (6.022 xx 10^23 "atoms")/(cancel"1 mol anything ever")#

#= color(blue)(4.20 xx 10^17 "Hg atoms")#

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