An example of the neutron absorption reaction is .
1 0 n+10 5 B-->7 3 Li+ 4 2 He
The rest masses of each particle in atomic mass units (u) are
1 0 n= 1 u
10 5 B=10 u
7 3 Li =7 u
4 2 He= 4 u
where 1u=1.66x10^-27 kg.
calculate Q
Q= in MeV
I have the same question please someone help me solve this. Thank you
Physics Someone help please! - Elena, Wednesday, May 8, 2013 at 6:14pm
¹₀n+¹º₅B = ⁷₃Li+⁴₂He
Δm = m(¹₀n) + m(¹º₅B) – m(⁷₃Li)-m(⁴₂He)=
=1.009 + 10.811 – 6.941 – 4.003 = 0.876 u.
ΔE=mc²=0.876 •1.66•10⁻²⁷•9•10¹⁶ =
=1.31•10⁻¹º J= =8.18•10⁸ eV =818 MeV
physice - Amy, Wednesday, May 8, 2013 at 6:33pm
Hi Elena thank you so much for your help but this answer is wrong i don't know why. Maybe because c is squared and did you squared c ? Please help me out
To calculate the Q-value of the neutron absorption reaction, you first need to determine the change in mass (∆m) of the reactants and products.
∆m = m(1₀n) + m(10₅B) - m(7₃Li) - m(4₂He)
= 1.009 u + 10.811 u - 6.941 u - 4.003 u
= 0.876 u
Now, convert the change in mass (∆m) to kilograms:
∆m = 0.876 u • (1.66 x 10^-27 kg/u) = 1.45296 x 10^-27 kg
To calculate the energy (∆E) associated with this change in mass, you can use the famous equation E = mc², where c is the speed of light (approximately 3 x 10^8 m/s).
∆E = ∆m • (c²)
= 1.45296 x 10^-27 kg • [(3 x 10^8 m/s)²]
= 1.45296 x 10^-27 kg • 9 x 10^16 m²/s²
= 1.307664 x 10^-10 J
Finally, convert the energy from joules to mega-electron volts (MeV). 1 MeV is equivalent to 1.6 x 10^-13 J.
∆E = 1.307664 x 10^-10 J • (1 MeV / 1.6 x 10^-13 J)
= 8.173525 x 10^2 MeV
≈ 818 MeV
Therefore, the Q-value of the neutron absorption reaction is approximately 818 MeV.