Question

Compute the mass of  ₉₂U²³⁵ + ₀n^1.

^{also known as Uranium -235}

^{please type out all steps.}

Answer 1

This is a nuclear reaction that occurs in two steps.

1) The U-235 atom combines with a neutron to produce U-236. As you can see, what we did was add the subscripts together (92 + 0 = 92) and the superscripts together as well (235 + 1). Since the subscript (atomic number) doesn't change, we still have Uranium but with a higher mass (the superscript) of 236.

₉₂U²³⁵ + ₀n¹ = ₉₂U²³⁶

We are asked about computing the mass of what is produced in this reaction, so the answer is 236amu. However, this doesn't mark the end of the reaction because we have a second step.

2) Now, the U-236 atom goes radioactive decay spontaneously because the ratio of mass/atomic number is too high. There is no rule to predict what elements will be produced but according to experiments the reaction that happens is the following:

₉₂U²³⁶ = ₅₆Ba¹⁴⁴ + ₃₆Kr⁸⁹ + ₀3n¹

So, the masses of the final products would be 144 amu (Ba) and 89 amu (Kr).