Cho hạt prôtôn có động năng Kp = 1,8 MeV bắn vào hạt nhân \(_3^7Li\) đứng yên, sinh ra hai hạt α có cùng độ lớn vận tốc và không sinh ra tia γ và nhiệt năng. Cho biết: mp = 1,0073 u; mHe = 4,0015 u; mLi = 7,0144 u; 1 u = 931MeV/c2 = 1,66.10-27 kg. Phản ứng này thu hay toả bao nhiêu năng lượng ?
A.Toả ra 17,4097 MeV.
B.Thu vào 17,4097 MeV.
C.Toả ra 2,7855.10-19 J.
D.Thu vào 2,7855.10-19 J.
\(_1^1p + _3^7 Li \rightarrow 2_2^4He\)
\(\Delta m = (m_p+m_{Li}- 2m_{He}) = 0,0187u>0 \)
=> \(m_t > m_s \), phản ứng tỏa năng lượng.
\(E = \Delta m c^2= 0,0187.931 =17,4097 MeV.\)
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