24.32 P - Chemistry: Molecular Nature Of Matter And Change

Question

Question: Radioisotopic dating depends on the constant rate of decay and formation of various nuclides in a sample. How is the proportion of ${}^{\mathbf{14}}\mathbf{\text{C}}$ kept relatively constant in living organisms?

Step-by-Step Solution

Answer

The organism is bombarded with ${}_7{}^{14}N$ from the atmosphere, the portion of ${}^{14}C$ remains relatively constant.

Step 1: C 14 Isotope

The isotope of carbon with eight neutrons emits radioactive rays. It is present in all the living organisms.  Once the organism dies, its amount steadily decreases in it. By measuring the amount of ${}^{\mathbf{14}}\mathbf{C}$ that remains, the age of the organism can be determined.

Step 2: Explanation

${}_7{}^{14}N{+}_0^{1}n{\to }_6^{14}C{+}_1^{1}H$

The neutrons in cosmic rays penetrate the atmosphere and keep the amount of ${}^{14}\text{C}$ almost constant because of the bombardment of ${}^{14} \text{N}$ atoms. Because living organisms absorb ${}^{14}\text{C}$, it remains relatively constant.