Question

Looking back at the equation for the fusion of uranium-235, if 100.0 g of uranium-235 undergoes fusion, how many grams of strontium-90 are produced and how much heat is produced?

Answer 1

The chemical equation is

₉₂U²³⁵ + ₀n¹ = ₃₈Sr⁹⁰ + ₅₄Xe¹⁴³ + 3 ₀n¹ + Energy

Moles of U-235 = mass/molecular weight

= 100g / 235.044g/mol

= 0.4255 mol

Moles of strontium-90 are produced = Moles of U-235 consumed

= 0.4255 mol

Mass of strontium-90 are produced = moles x molecular weight

= 0.4255 mol x 89.908 g/mol = 38.252 g

Energy produced = [(mass of U-235 + mass of n) - (mass of Sr-90 + mass of Xe-143 + 3 x mass of n)] x c²

E = [(235.044 + 1.00867) - (89.908 + 142.935 + 3*1.00867)] amu x 1.66 x 10^-27 kg/amu x (3*10^8 m/s)^2

= 0.18366 amu x 1.66 x 10^-27 kg/amu x (3*10^8 m/s)^2

= 2.74 x 10^-11 J / U-235 atom x 6.023 x 10^23 atoms/mol

= 1.65 x 10^13 J / U-235 mol

Heat produced by 0.4255 mol

= (1.65 x 10^13 J / U-235 mol) x 0.4255 mol U-235

= 7.03 x 10^12 J