The Q value of a nuclear reaction
A+b=C+d is defined by `Q=[m_A+m_b-m_C-m_d]c^2` where the masses refer to the respective nuclei. Determine form the given data the Q value of the following reactions and state whether the reactions are exothermic of endothermic.
(i) `._1H^(1)+._1H^3to ._1H^2+._1H^2`
(ii) `._6C^(12)+._6C^(12) to ._10Ne^(20)+._2He^4`
Atomic masses are given to be
`m(._1H^2)=2.014102u , m(._1H^3)=3.016049 u, m(._6C^(12))=12.000000u , m(._10Ne^(20))=19.992439u`

Explanation

Atomic masses are given to be
`m(""_(1)H^(2)) c^(2)`
`=(1.007825 +3.016049 - 2.014102 - 2.014102)u xx c^(2)`
`=(4.023874 - 2.014102 - 2.014102) u xx c^(2)`
`=-0.00433 xx 931.5 MeV =-4.03 MeV`
The Q-value of the reaction is negative, so the reaction is endothermic.
(ii) For the given reaction:
`""_(6)C^(12) + ""_(6)C^(12) to ""_(10)Ne^(20) + ""_(2)He^(4)`
`Q =(m(""_(6)C^(12)) + m(""_(6)C^(12)) -m(""_(10)Ne^(20))-m(""_(2)He^(4))c^(2)`
`=0.004958 xx 931.5 = 4.62` MeV
The Q-value o f the reaction is positive, so the reaction is exothermic.