Radioactive iodine-131 is widely used in medical diagnostics

CHEMISTRY · Multi-part · US High School · Chemistry · Atomic Structure & Nuclear · Atomic Structure & Nuclear

Problem

Radioactive iodine-131 is widely used in medical diagnostics. A hospital receives a sealed vial that initially contains 2.0 g of pure

^{131}\text{I}

(atomic mass

131\,\text{g mol}^{-1}

). The half-life of

^{131}\text{I}

is 8.0 d. (a) Determine the mass of

^{131}\text{I}

that remains undecayed after 24 d in storage. (b) Calculate the numerical value of the decay constant for

^{131}\text{I}

in units of

\text{d}^{-1}

. (c) Suppose the vial is opened 40 d after delivery. What fraction of the original activity (decays per unit time) is still present at that moment? Express the fraction as a decimal to two significant figures.

Related theory

Chemical Kinetics

Browse the problem library