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# Atomic mass question watch

1. edited
2. (Original post by michelleworth)
Using the atomic masses of 65Ni and 65Cu, calculate the Q-value of the β- decay of 65Ni (in MeV). The answer is 2.14 MeV.

65Ni -> 65Cu + e-
64.9308 -> 64.9277 + 0.0005485
Products - Reactants
-0.0025515 * 931.5 = 2.3767 MeV

Are my equations correct? My answer is in the same ball park but not correct.
Atomic mass of Ni-65 is 64.930084304.

For negative beta decay, you just need to have
Q-value = (atomic mass of Ni65 in amu - atomic mass of Cu65 in amu)*931 MeV/amu
3. (Original post by michelleworth)
Could you help me with this one as well please?

Calculate the Q value for the EC decay of 152Eu.
a) 1.874 MeV
b) 0.852 MeV
c) -0.852 MeV
d) 1.799 MeV

Is the Q value the atomic mass of 152EU - the atomic mass of 152Sm? That would give me 1.874MeV but I'm not sure if an electron mass should be included or an electron binding energy.
Are you provided with the nuclear equation? If yes, please provide it. Thanks.
4. (Original post by michelleworth)
Could you help me with this one as well please?

Calculate the Q value for the EC decay of 152Eu.
a) 1.874 MeV
b) 0.852 MeV
c) -0.852 MeV
d) 1.799 MeV

Is the Q value the atomic mass of 152EU - the atomic mass of 152Sm? That would give me 1.874MeV but I'm not sure if an electron mass should be included or an electron binding energy.
(Original post by michelleworth)
No the following is all I have, but I looked it up and 152EU decays to 152Sm via electron capture

Calculate the Q value for the EC decay of 152Eu.
a) 1.874 MeV
b) 0.852 MeV
c) -0.852 MeV
d) 1.799 MeV
For negative beta decay and electron capture, electron mass is not required for calculating Q-value. You can prove it using mass-defect relation.
5. (Original post by michelleworth)
Would you agree with my answer of 1.874 MeV?
Provided that your atomic mass is correct. It seems reasonable.
6. (Original post by michelleworth)
Can I ask one final question - do you agree with my answer of 0.143 MeV for this question? The maximum kinetic energy is equal to the Q value of the decay, so I calculated the Q value as 0.314 MEv, then subtracted 171 KeV to get 0.143 MeV Do you agree with this?

A 191Os nucleus decays via β- emission to an excited state of 191Ir at 171 keV. What is the maximum kinetic energy of the electron on the β spectrum?
a) 0.134 MeV
b) 0.143 MeV
c) 0.171 MeV
d) 1.859 MeV
Seems good.
7. (Original post by michelleworth)
edited

Please do not edit and delete the original question or post threads without a proper title.

This wastes other peoples time, is unhelpful and is likely to pick up a card from the moderators. Continued misuse of the forum will result in a ban.

Thanks.

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