What is the mass of 25.0 mCi of ⁹⁹Tc^m which has a half-life of 6.00 h?

Question

Quizplus · Accepted Answer

The activity (A) is related to the number of atoms (N) by A = λN, where λ is the decay constant. The decay constant λ can be calculated using the half-life (T₁/₂) with the formula λ = 0.693/T₁/₂. Using the activity (25.0 mCi = 25.0 x 10⁻³ Ci = 25.0 x 10⁻³ x 3.7 x 10¹⁰ Bq), we can find N. Then, using the molar mass of ⁹⁹Tc (99 g/mol), we can convert N to mass. The calculation results in approximately 4.74 ng.

What Is the Mass of 25