The nuclear reaction, n + 5 10 B → 3 7 L i + 2 4 H e is observed to occur even when very slow - moving neutrons M n = 1.0087 u strike a boron atom at rest. For a particular reaction in which K n ≈ 0 ,

Question

The nuclear reaction, n + 5 10 B → 3 7 L i + 2 4 H e is observed to occur even when very slow - moving neutrons M n = 1.0087 u strike a boron atom at rest. For a particular reaction in which K n ≈ 0 , the helium M H e = 4.0023 u is observed to have a speed of 9.30 × 10 6 m / s . Determine the Q - value of the reaction.

TestHub · Accepted Answer

We are given that data K a = K X = 0 , so Q = K L i + K H e , Where K H e = 1 2 M H e v H e 2 = 1 2 4.0026 1.66 × 10 - 27 9.30 × 10 6 2 = 2.87 × 10 - 13 J = 1.80 M e V by momentum conservation 2 × 7 K L i = 2 × 4 K H e K L i = 4 7 K H e = 4 7 × 1.8 = 1.02 Hence, Q = 1.02 M e V + 1.80 M e V = 2.82 M e V

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