# 74.nuclear fission

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• Author : Khairi

NUCLEAR FISSION

A process of splitting of a heavy nucleus into two lighter nuclei The heavy nucleus is bombarded by a neutron

At end of the process,it produces ;

Two new nuclei Three neutrons Nuclear energy

• Author : Khairi

Uranium-235

neutron

NUCLEAR FISSION

• Author : Khairi

NUCLEAR FISSION

• Author : Khairi

2 new nuclei,3 neutrons and energy produced

NUCLEAR FISSION

• Author : Khairi

neutron

Uranium-235

Krypton-92

Barium-141

neutron

neutron

neutron

NUCLEAR FISSION

• Author : Khairi

NUCLEAR FISSION EQUATION

U23592 Kr9236Ba14156n10+ + + n103 + energy

EXERCISE

Calculate the nuclear energy produced in the nuclear fissionabove in Joule and eV.

2.69 x 10-11 J

Uranium-235 = 235.04 a.m.uKrypton-92 = 91.93 a.m.uBarium-141 = 140.91 a.m.uNeutron = 1.01 a.m.u

NUCLEAR FISSION

• Author : Khairi

Mass defect = mass before mass after

= [235.04 + 1.01] [140.91 + 91.93 + 3(1.01)]

= 0.18 a.m.u

= 0.18 x 1.66 x 10-27 kg

= 2.988 x 10-28 kgE = mc2

= 2.988 x 10-28 x (3.0 x 108)2

= 2.69 x 10-11 J

NUCLEAR FISSION

= 1.68 x 108 eV

U23592 Kr9236Ba14156n10+ + + n103 + energyNUCLEAR FISSION EQUATION

• Author : Khairi

CHAIN REACTION

A chain reaction occurs when a further nuclear fission is continuously occurred.

This is happen when the neutron which is produced in earliernuclear fission bombarding the new nuclei.

Again,the process will produce 2 new nuclei,3 neutron and nuclearenergy.

Chain reaction only can happen when the mass of uranium isexceeded the critical mass.

NUCLEAR FISSION

• Author : Khairi

neutron

NUCLEAR FISSION

CHAIN REACTION

• Author : Khairi

neutron

NUCLEAR FISSION

CHAIN REACTION

• Author : Khairi

In the fission reaction for an atom of uranium-235,the energyproduced is 2.9 x 10-11 J.What is the total loss of mass in the reaction ?

A. 3.22 x 10-28 kgB. 9.67 x 10-20 kg

C. 2.61 x 106 kgD. 1.03 x 1019 kg

E = mc2

2.9 x 10-11 = m x (3 x 108)2

m = 3.22 x 10-28 kg

PAST YEARS QUESTIONPAST YEARS QUESTION

• Author : Khairi

a. What is meant by nuclear fission ?

A process of splitting a heavy nucleus into two lighter nuclei

b. What is meant by nuclear fusion ?

A process of combining two heavy nuclei to form a heavier nucleus

PAST YEARS QUESTIONPAST YEARS QUESTION

• Author : Khairi

c. Using the information in the table,compare the nuclear fission and nuclear fusion.Hence state the relationship between mass and energy evolved.

1. Nuclear fission is a process of splitting a heavy nucleus to lighter nuclei while nuclear fusion is a process of combining light nuclei to heavier nucleus

2. Both reactions release nuclear energy

3. Nuclear energy released due to mass loss

PAST YEARS QUESTIONPAST YEARS QUESTION

• Author : Khairi

Describe how the chain reaction happens in a nuclear fission of an atom of uranium.

neutron

Heavy nucleus

3 neutrons

Light nucleus

Heavy nucleus

Heavy nucleus is bombarded by neutron

Two lighter nuclei and three neutron are producedNeutron continue to hit the new nuclei and produce twolighter nuclei and three neutron

PAST YEARS QUESTIONPAST YEARS QUESTION

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