USES OF RADIOACTIVE ISOTOPES
a) Study of reaction mechanism
i) Mechanism of photosynthesis in plants
A small quantity of Radioactive C O 2(iso) containing radioactive oxygen O18 is mixed with ordinary carbondioxide and the process is carried out. It has been found that oxygen gas evolved along with sugar formation is non-radioactive.
Therefore O2 produced comes from water and not from carbondioxide. So the correct mechanism is as follows.
6C O2(iso) + 6H2O ® C6H12 O6 + 6O2(iso)
ii) Study of hydrolysis of ester
By labelling oxygen, the mechanism of ester hydrolysis can be studied by using water labelled with O18. The hydrolysis of an ester by water enriched with radioactive oxygen is indicated as :
Therefore it is the acid and not alcohol produced which is radioactive confirming the above mechanism.
Radioactive isotopes which are useful in medicine
i. Measure water content of the body
ii. Brain scan
iv. Diagnosis of damaged heart muscles and hyper
v. Kidney scan
vi. Diagnosis of anemia
vii. Treatment of cancer
viii. Location of blood clots and circularity disorders
Gold - 198 Curing of cancers
NUCLEAR REACTIONS TAKING PLACE IN SUN (STARS)
It has been estimated that the sun is giving out energy equally in all possible directions at the rate of 3.7 × 1033 ergs/sec. The energy of the sun is supposed to arise from the fusion of hydrogen nuclei into helium nuclei which in going on inside it all the time.
The various fusion reactions taking place in the sun are as follows: