Calculating the energy that is released in nuclear fusion

In summary, the conversation discusses the calculation of binding energy and the discrepancy in the mass of a proton as stated in the formula sheet and the mark scheme. The formula sheet provides the mass of a proton as 1.00728 u, which may have been overlooked, causing confusion for the person asking the question. The conversation ends with the clarification that the mass of a proton is indeed given in the formula sheet.
  • #1
Tangent100
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Question 1. c) (ii) on this AQA paper... http://filestore.aqa.org.uk/subjects/AQA-PHYA5-1-QP-JUN13.PDF

The solution is here http://filestore.aqa.org.uk/subjects/AQA-PHYA5C-W-MS-JUN13.PDF

So I know that the binding energy will be the mass defect so the value of energy on the left hand side is bigger compared to the right hand side. To find the energy, in MeV, that is released it would be the change in mass that is in MeV. So I'd subtract the combined mass in u on the left from the combined mass of u on the right, then convert the final value to MeV from u.

The problem is the left hand side, the hydrogen atom. The mark scheme states that it is 1.00728 u.

I don't get that... From the formula sheet, http://filestore.aqa.org.uk/subjects/AQA-PHYA4-5-INS-JUN12.PDF, the mass of a proton is 1.67(3)x10^-27. Naturally, to combine to u, I would do 1.673/1.661... but that is not 1.00728 but 1.00722!

Could someone explain where they got their value from? Am I meant to take Hydrogen to be 1.00728 for granted, and so it is simply just the mass in u of hydrogen that I was suppose to know all the way along by memory? Seeing that they done no calculation to get that value, it makes me feel so. Thank you.
 
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  • #2
Note that 1.00728 u has 6 significant figures. So, to arrive at this number from the mass in kg, you would need to know the mass of the proton in kg to 6 significant figures as well as the conversion factor from kg to amu to 6 significant figures.

But you are right, the formula sheet does not give sufficient information. Probably just an oversight of whoever made up the exam.
 
  • #3
Oops... A closer inspection of the formula sheet does show that the mass of the proton is given as 1.00728 u.
 

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  • #4
TSny said:
Oops... A closer inspection of the formula sheet does show that the mass of the proton is given as 1.00728 u.
OHH okay I had no idea they could of placed it there! I was looking on the right hand side of this formula sheet for numbers not the left... Okay cool thanks for your help.
 

1. How is energy released in nuclear fusion?

Energy is released in nuclear fusion when two atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy in the process. This energy is released due to the conversion of a small amount of mass into energy, as described by Einstein's famous equation E=mc^2.

2. What factors affect the amount of energy released in nuclear fusion?

The amount of energy released in nuclear fusion depends on the types of nuclei involved, the temperature and pressure of the fusion reaction, and the efficiency of the fusion process. Higher temperatures and pressures generally result in greater energy release, while the type of nuclei can influence the amount and type of energy released.

3. How do scientists calculate the energy released in nuclear fusion?

Scientists use complex mathematical equations and models to calculate the energy released in nuclear fusion. These calculations take into account the factors mentioned above, as well as other variables such as the rate of fusion reactions and the energy lost through radiation.

4. What are some potential applications of nuclear fusion energy?

Nuclear fusion has the potential to provide a nearly limitless source of clean, renewable energy. It is currently being researched as a potential solution to the world's energy needs, with the aim of developing fusion reactors that can produce more energy than is required to sustain the fusion reaction.

5. Are there any risks associated with nuclear fusion?

While nuclear fusion itself does not produce any greenhouse gases or long-lived radioactive waste, there are still potential risks associated with the technology. These include the high temperatures and pressures required for fusion reactions, as well as the potential for accidents or malfunctions in fusion reactors. However, research is ongoing to address and mitigate these risks.

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