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Starting with 1.20 g A, what is the mass of A remaining undercomposed after 1.00h? ( t1/2= 16 min)
you can simplify this formula: \[A=A _{0}e ^{-kt}\] to this: \[A=A _{0}(\frac{ 1 }{ 2 })^{\frac{ t }{ t _{1/2} }}\] A=amount after time elapsed Ao=initial amount t= time t1/2= half life
you can also approximate 16min as 1/4 of 1 hour, so 4 half-lives will pass over that time span. 1/16 of the 1.20g will remain after 1 hour (more or less)