An example of the neutron absorption reaction is .

Question

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

Answer 1

You do not need to use E=mc^2. Calculate the sum of mass of products in (u) and mass of reactants in (u). Then, mass of product minus mass of reactants. It will be negative, which means energy is released (exorgenic rxn)and Q will be positive. Now, to find Q in Mev, Take that difference of mass that you found in u (without minus)and multiply by 931.5 Mev, and this will be th final answer.

Answer 2

I keep getting it wrong I did how you said it but i still keep getting it wrong please help me out...thank you!

Answer 3

The final answer will be 2.80 MeV
On the left side of quation is 11.0216024 (u), on the right side 11.0186074. So,11.0186074-11.0216024=-0.0029954 (we use positiv value for Q).Q= 0.0029954 u *931.5 MeV/u = 2.79 MeV