Question

A vessel of volume 125 cm3 contains tritium (3H, t1/2 = 12.3 y) at 500 kPa and 300 K. Calculate the activity of the gas.

Answer 1

Answer:

It is given:

• Vessel’s volume, V = 0.125 L = 125 cm3  

• Tritium’s half-life time, $\mathrm{t} 1 / 2=3.82 \times 108 \mathrm{s}=12.3 \mathrm{y}$

• Pressure, P = 5 atm = 500 kpa

• Temperature, T = 300 K,

• Constant of disintegration, λ = 0.693t1/2

• $=0.6933 .82 \times 108=1.81 \times 10-9 \mathrm{s}-1$

• Undecayed atoms left, $\mathrm{N}=\mathrm{n} \times 6.023 \times 1023$

• $=5 \times 10-2 \times 0.1258 .2 \times 3 \times 6.023 \times 102 \times 1023$  

• Therefore, n = PVRT = 1.5×1022 atoms

• Activity, A = λN

• $=2.7 \times 1013$ disintegration/sec

• Therefore, A = 729.72 Ci