| Date | November 2017 | Marks available | 2 | Reference code | 17N.3.hl.TZ0.18 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Calculate | Question number | 18 | Adapted from | N/A |
Question
In the 20th Century, both fission and fusion were considered as sources of energy but fusion was economically and technically unattainable.
Calculate the loss in mass, in kg, and the energy released, in J, when 0.00100 mol of 228Ac decays, each atom losing an electron. Use section 2 of the data booklet and E = mc2.
228Ac → + 228Th
Determine the energy released, in J, by 0.00100 mol of 228Ac over the course of 18 hours.
Outline how nuclear ionising radiation can damage DNA and enzymes in living cells.
Markscheme
Loss in mass:
«(3.78532 x 10–25 kg – 9.109383 x 10–31 kg – 3.78528 x 10–25 kg) x 0.00100 x 6.02 x 1023 =»1.86 x 10–9 «kg»
Energy released:
«E = mc2 = 1.86 x 10–9 kg x (3.00 x 108 m s–1)2 =» 1.67 x 108 «J»
«1.67 x 108 J x =» 1.46 x 108 «J»
production of radicals/•O2–/•OH
OR
direct effect such as breaking bonds/atom migration
Ignore missing dots on radical species.
Accept named radical eg “superoxide radical” OR “hydroxyl radical”.
An example must be given for second alternative.
