The proton mass is 1.007276 amu , the neutron mass is 1.008665 amu , and the ele

Question

The proton mass is 1.007276 amu , the neutron mass is 1.008665 amu , and the electron mass is 5.486×104 amu . Part A What is the expected mass of a fluorine-19 nucleus, based on the total mass of its protons and neutrons?

Part B The actual measured mass of a fluorine-19 atom is 18.998403 amu . What is the mass defect, m, for a fluorine-19 nucleus?

Part Part C What is the binding energy for a fluorine-19 nucleus?

Part D What is the binding energy, E, for a fluorine-19 nucleus in MeV/nucleon? Recall that 1 MeV=1.60×1013 J.

Explanation / Answer

The flourine has an atomic number of 9, this is the number of protons , this particular atom has an atomic mass of 19 this is that the sum of neutrons and protons is equal to 19 so

protons + neutrons = 19

neutrons = 19 - 9 = 10 neutrons

since the atom is supposed to be neutral then the number of electrons must be equal to the number of protons so we have 9 electrons

the expected mass of this atom is

9 * 1.007276 + 10*1.008665 = 19.1521 amu

Mass defect is the difference between th expected mass and the actual mass

Actual mass 18.998403

Mass defect = 19.1521 - 18.998403 = 0.1537 amu

to express the binding energy this is usually done in Joules, so the first thing to do is to change the amu to kg, this can be done by dividing the mass defect by 1.6605 x 10-27 so

0.1537 amu x 1.6605 x 10-27 Kg/amu = 2.55 x 10-28 Kg

then apply the equation

E = m *c2 where E is energy, m is mass and c is the lightspeed which is 3 x108

E = 2.63 x 10-28 Kg * (3 x108 )2 = 2.2975 x 10-11 Joules / mol

D) divide the last result by 1.60×10?13 , this is the equivalence given in the statement

this is  2.2975 x 10-11 / 1.60×10?13 = 1.44 x 102 Mev / mol

then remember that we have 19 nucleons in 1 atom of F-19, so divide this last result by 19

1.44 x 102 / 19 = 7.5577 Mev / nucleon

*if this answer is helpful dont forget to rate it =)

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