Of the four fundamental forces, the strong nuclear force is…
Orla holds a single pellet of uranium fuel, smaller than her thumb. To release as much energy by burning coal, she would need several loaded train cars. Why is the nuclear fuel worth so much more, kilogram for kilogram?
In the particles topic, you saw that the strong nuclear force is the strongest of the four fundamental forces, and that it is what holds a nucleus's protons and neutrons together. In the last topic, you saw that an energy-releasing nuclear reaction converts a little of its mass, its mass defect, into the released energy. Those two ideas together explain the pellet.
A chemical change rearranges a material's electrons.
The electromagnetic force holds those electrons in place.
A nuclear change rearranges the protons and neutrons of the nucleus itself.
The strong nuclear force holds those protons and neutrons together.
The strong nuclear force is far stronger than the electromagnetic force.
Rearranging what the far stronger force holds converts a far larger fraction of the material's mass to energy.
The fraction of the material's mass converted in a nuclear change is around a million times larger than in a chemical change.
Splitting the nuclei in 1 kg of uranium releases about as much energy as burning several thousand tonnes of coal.
Propane burns in a camp stove. Is this a chemical change or a nuclear change, and which force's grip on the material is being rearranged?
Burning rearranges how atoms bond; every nucleus is untouched.
So burning propane is a chemical change.
A chemical change rearranges electrons, and the electromagnetic force holds those electrons.
Burning propane is a chemical change. It rearranges electrons held by the electromagnetic force.
Splitting the nuclei in 1 kg of a nuclear fuel releases about 6.0 × 10¹³ J. Burning 1 kg of a chemical fuel releases about 3.0 × 10⁷ J. How many times more energy per kilogram does the nuclear fuel release?
The ask is a ratio: the nuclear fuel's energy per kilogram divided by the chemical fuel's.
Divide the two mantissas: 6.0 ÷ 3.0 = 2.0.
Divide the two powers of ten: 10¹³ divided by 10⁷ leaves 10⁶.
The nuclear fuel releases about 2.0 × 10⁶ times more energy per kilogram, around a million times more.
Which particles does a chemical change rearrange?
The strong nuclear force holds a nucleus's protons and neutrons together. Which force holds an atom's electrons in place?
Blanka says: 'For the same mass of material, a nuclear change converts around a million times more of the material's mass into released energy than a chemical change does.' Is Blanka correct?
For the same mass of material, why do nuclear reactions release around a million times more energy than chemical reactions?
Splitting the nuclei in 1 kg of uranium releases about 8.0 × 10¹³ J. Burning 1 kg of coal releases about 3.2 × 10⁷ J. How many times more energy does the uranium release? Give your answer to two significant figures.
A chemistry class burns 1 kg of propane. A power station splits the nuclei in 1 kg of uranium. About how many times more energy does the uranium release?