Chapter 25: Nuclear Chemistry Table of Contents Chapter 25: Nuclear Chemistry Fission, Fusion, Nuclear issues

So…half-lives are constant. Nuclear Chemistry: Additional Concepts 1. Radiochemical Dating Nuclear reaction rates remain constant regardless of changes which effect other chemical reactions So…half-lives are constant. Radiochemical dating: determining the age of an object by measuring the amount of a certain radioisotope remaining in that object.

Nuclear Chemistry: Additional Concepts 2. Nuclear fission Heavy atoms (mass number > 60) tend to break into smaller atoms, increasing their stability. Nuclear fission: splitting an atomic nuclei into 2 approximately equal parts. Chain reaction releases a large amount of energy. Critical mass: The minimum amount of mass the starting material must have to sustain a chain reaction

Understand the pros and cons Nuclear Chemistry: Additional Concepts Nuclear reactors Nuclear power plants use the process of nuclear fission to produce heat in nuclear reactors. The heat is used to generate steam, which is then used to drive turbines that produce electricity. 7/8/10 –US Dept. of Energy announced $18.2 million for education in Nuclear Energy. Understand the pros and cons

2) What controls the temp? How? 1) What is the role of the fuel rods? Nuclear Chemistry: Additional Concepts Nuclear reactors 2) What controls the temp? How? 1) What is the role of the fuel rods? FISSION → energy Water slows neutrons 3) What keeps the process under control? How? Control rods absorb neutrons

Cadmium and boron are used to keep the fission process under control. Nuclear Chemistry: Additional Concepts Nuclear reactors Fissionable uranium(IV) oxide (UO2) is commonly used as fuel in nuclear reactors. Cadmium and boron are used to keep the fission process under control.

1 MWh = Energy for 650 houses, per hour. 1 ton of coal = 2.5 MWh

reactors able to produce more fuel than they use Breeder reactor reactors able to produce more fuel than they use

Yucca mountain – site for nuclear waste storage http://upload.wikimedia.org/wikipedia/commons/2/23/Wfm_area51_map_en.png Yucca mountain – site for nuclear waste storage

2. Nuclear fission Famous nuclear meltdowns 3 mile island (1979) – US Chernobyl (1986) – Ukraine several human errors & technical malfunctions Fukushima (2011) – Japan Following earthquake

Radiation energetic enough to ionize matter Ionizing Radiation Radiation energetic enough to ionize matter

Nuclear Power: 65,100 MW produced per water tower. US uses 4 GW/yr, from 104 operating units. (100 GW possible). Upside: most energy produced, produces weapons-grade Pu Downside: requires U, & produces waste that will be radioactive for 4.5 billion years.

release very large amounts of energy Nuclear Chemistry: Additional Concepts 3. Nuclear fusion Nuclear fusion: nuclear reaction where small nuclei combine to form larger ones. release very large amounts of energy require extremely high temperatures. (also called thermonuclear reactions)

Solar Energy: Sun = the source of all energy on our planet. The sun makes ~35,000 times the total energy used by man. ~1/3 of this energy is either absorbed by the atmosphere or reflected back into space. 40,000 watts of light per sq. in. of its surface, per second.

Additional Assessment Questions Comprehension What is the difference between nuclear fusion and nuclear fission? Nuclear fusion is the combining of nuclei to form a single nucleus. Nuclear fission is the splitting of a nucleus into fragments.