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(a) A deuteron, \({ }_{1}^{2} \mathrm{H},\) is the nucleus of a hydrogen isotope and consists of one proton and one neutron. The plasma of deuterons in a nuclear fusion reactor must be heated to about 300 million \(\mathrm{K}\). What is the rms speed of the deuterons? Is this a significant fraction of the speed of light in vacuum \(\left(c=3.0 \times 10^{8} \mathrm{~m} / \mathrm{s}\right) ?(\mathrm{~b})\) What would the temperature of the plasma be if the deuterons had an rms speed equal to \(0.10 \mathrm{c}\) ?

Short Answer

Expert verified
The root mean square speed of the deuterons at 300 million K is calculated using the given formula and compared to the speed of light. Following this, the temperature of the plasma is calculated assuming the deuterons had a root mean square speed equal to 10% of the speed of light.

Step by step solution

01

Calculate the rms speed of the deuterons

First, we need to calculate the rms speed for a temperature of 300 million K. We start by identifying the given information. We know that temperature \(T = 3.0 \times 10^8\ \mathrm{K}\), the Boltzmann constant \(K = 1.38 \times 10^{-23}\ \mathrm{J\ /\ K}\) and the mass of a deuteron \(m = 2 \times 1.673 \times 10^{-27}\ \mathrm{kg}\). We then substitute these values into the equation \(v_{rms}=\sqrt{(3KT/m)}\).
02

Compare the rms speed with the speed of light

After calculating the rms speed, we compare it to the speed of light \(c = 3.0 \times 10^8\ \mathrm{m/s}\). The result will give an estimate as to what percentage of the speed of light the deuterons are moving at.
03

Calculate the temperature when the rms speed is 0.10c

For the second part of the problem, we rearrange the equation to solve for temperature. If \(v_{rms} = 0.10c\), then we can substitute this value into the leg-side of the formula \(T = m(v_{rms})^2 / 3K\). Solving this will give us the temperature of the plasma if the deuteron's speed were 10% of the speed of light.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Nuclear Fusion
Nuclear fusion is an incredible process where two light atomic nuclei merge to form a heavier nucleus. This process releases a tremendous amount of energy, which is the same energy that powers our sun. Fusion is not only a source of immense power, but it is also clean and produces little to no greenhouse gases.
  • In nuclear fusion reactors, typically hydrogen isotopes, like deuterons, are used.
  • For nuclear fusion to occur, these particles must collide with sufficient energy to overcome the strong repulsive forces between them.
  • This requires extremely high temperatures, much like what is achieved in stars.
Achieving controlled nuclear fusion on Earth has long been a scientific dream due to its potential as a sustainable energy source. However, the conditions necessary for fusion—extremely high temperatures and pressures—pose significant technological challenges.
Plasma Temperature
Plasma is often called the fourth state of matter. In a plasma state, the atoms are ionized, which means they have lost their electrons and become positive ions.
  • Plasma temperatures in fusion reactors can reach hundreds of millions of Kelvin.
  • At these temperatures, the ions move extremely fast, increasing the likelihood of collisions that can lead to fusion.
High plasma temperatures are vital in nuclear fusion research because they facilitate the high-speed movement of ions necessary for overcoming electrostatic barriers between them. Monitoring and controlling these temperatures is crucial for sustaining the fusion process. In the exercise, the deuteron plasma needs to reach approximately 300 million Kelvin to detect and sustain fusion reactions.
Boltzmann Constant
The Boltzmann constant is a fundamental constant in physics that relates the average kinetic energy of particles in a gas with the temperature of the gas. It serves as a bridge between macroscopic and microscopic physics.
  • The value of the Boltzmann constant is approximately \(1.38 \times 10^{-23}\ \text{J/K}\).
  • This constant is used extensively in thermodynamics and statistical mechanics.
In the context of the exercise, the Boltzmann constant plays a crucial role in determining the root-mean-square (rms) speed of the deuterons. The rms speed formula \(v_{rms}=\sqrt{(3KT/m)}\) is derived using the Boltzmann constant, where \(K\) is the Boltzmann constant, \(T\) is the temperature in Kelvin, and \(m\) is the mass of a particle. This equation helps in finding how fast the deuterons are moving at a given temperature, crucial information for assessing conditions needed for nuclear fusion.

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Most popular questions from this chapter

Three moles of an ideal gas are in a rigid cubical box with sides of length \(0.300 \mathrm{~m}\). (a) What is the force that the gas exerts on each of the six sides of the box when the gas temperature is \(20.0^{\circ} \mathrm{C} ?\) (b) What is the force when the temperature of the gas is increased to \(100.0^{\circ} \mathrm{C} ?\)

The gas inside a balloon will always have a pressure nearly equal to atmospheric pressure, since that is the pressure applied to the outside of the balloon. You fill a balloon with helium (a nearly ideal gas) to a volume of \(0.600 \mathrm{~L}\) at \(19.0^{\circ} \mathrm{C}\). What is the volume of the balloon if you cool it to the boiling point of liquid nitrogen \((77.3 \mathrm{~K}) ?\)

What is one reason the noble gases are preferable to air (which is mostly nitrogen and oxygen) as an insulating material? (a) Noble gases are monatomic, so no rotational modes contribute to their molar heat capacity; (b) noble gases are monatomic, so they have lower molecular masses than do nitrogen and oxygen; (c) molecular radii in noble gases are much larger than those of gases that consist of diatomic molecules; (d) because noble gases are monatomic, they have many more degrees of freedom than do diatomic molecules, and their molar heat capacity is reduced by the number of degrees of freedom.

Helium gas with a volume of \(3.20 \mathrm{~L}\), under a pressure of 0.180 atm and at \(41.0^{\circ} \mathrm{C}\), is warmed until both pressure and volume are doubled. (a) What is the final temperature? (b) How many grams of helium are there? The molar mass of helium is \(4.00 \mathrm{~g} / \mathrm{mol}\).

A person at rest inhales \(0.50 \mathrm{~L}\) of air with each breath at a pressure of 1.00 atm and a temperature of \(20.0^{\circ} \mathrm{C}\). The inhaled air is \(21.0 \%\) oxygen. (a) How many oxygen molecules does this person inhale with each breath? (b) Suppose this person is now resting at an elevation of \(2000 \mathrm{~m}\) but the temperature is still \(20.0^{\circ} \mathrm{C}\). Assuming that the oxygen percentage and volume per inhalation are the same as stated above, how many oxygen molecules does this person now inhale with each breath? (c) Given that the body still requires the same number of oxygen molecules per second as at sea level to maintain its functions, explain why some people report "shortness of breath" at high elevations.

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