Mass Defect & Nuclear Binding Energy (CIE A Level Physics)

Data for a nucleus and some particles are given in Table 9.1.

Table 9.1

nucleus or particle	mass / u
	138.955
	1.00863
	1.00728
	5.49 × 10–4

One nuclear reaction that can take place in a nuclear reactor may be represented, in part, by the equation shown below.

Complete the equation.

[3]

(ii)

Calculate the binding energy per nucleon, in MeV, of lanthanum-139 ( ).

binding energy per nucleon = ..................................... MeV [3]

State and explain whether the binding energy per nucleon of uranium-235 ( ) is greater, equal to or less than the binding energy per nucleon of lanthanum-139 ( ).

Fig. 1.1

[2]

A nuclear fission reaction occurs that has the following equation 

(i)

Determine, for this nuclear reaction, the value of .

[1]

Table 1.2

[2]

Under the right conditions, a hydrogen-2  nucleus can fuse with a hydrogen-1 to make a helium-3 nucleus. The values of binding energy per nucleon for these nuclei are shown in Table 1.3.

Table 1.3

Nuclei	binding energy per nucleon / MeV
	0.864
	2.235

When two hydrogen-2 nuclei fuse into a helium-4 nucleus, 3.6 × 10⁻¹² J of energy is released. This reaction is shown below

Show that the fusion of 1 kg of two hydrogen-2 nuclei releases about 8 times more energy per kg than the fission of 1 kg of uranium-235.

The masses of hydrogen-2 and uranium-235 are shown in Table 1.4.

Table 1.4

Define the terms 

If deuterium  nuclei undergo fusion, a possible reaction is

Table 1.1

Fig. 1.2 shows the variation of nucleon number with the binding energy per nucleon of a nucleus.

Fig. 1.2

With reference to Fig. 1.2, state and explain

Fission and fusion reactions release different amounts of energy.

Explain why the energy released per nucleon from fusion is greater than that from fission. State the feature of the graph in Fig. 1.2 that shows this.