Question 19M.3.hl.TZ1.a(iii)
| Date | May 2019 | Marks available | [Maximum mark: 3] | Reference code | 19M.3.hl.TZ1.a(iii) |
| Level | hl | Paper | 3 | Time zone | TZ1 |
| Command term | Determine | Question number | a(iii) | Adapted from | N/A |
Uranium-235, 235U, is bombarded with a neutron causing a fission reaction.
Two products of the fission of 235U are 144Ba and 89Kr.
The masses of the particles involved in this fission reaction are shown below.
Mass of neutron = 1.00867 amu
Mass of U-235 nucleus = 234.99346 amu
Mass of Ba-144 nucleus = 143.89223 amu
Mass of Kr-89 nucleus = 88.89788 amu
Determine the energy released, in J, when one uranium-235 nucleus undergoes fission. Use this data and information from sections 1 and 2 of the data booklet.
[3]
«Δm mass of reactants-mass of products»
Δm = «234.99346 – 143.89223 – 88.89788 – (2 × 1.00867) =» 0.18601 «amu» [✔]
Δm = «0.18601 amu × 1.66 × 10−27 kg amu–1 =» 3.09 × 10–28 «kg» [✔]
E = «mc2 = 3.09 × 10–28 kg × (3.00 × 108 m s–1)2 =» 2.78 × 10–11 «J» [✔]
Note: Award [3] for correct final answer.
The calculation of the energy released in was done reasonably well. Some candidates answered this very well and scored full marks. However, many scored 1 or 2 marks out of 3 through ECF marks. Common errors were incorrect calculation of mass in amu, or omission of converting amu to kg. Here, it was apparent that good setting out of calculations was effective in scoring for partially correct responses.
