Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: mandy9008 on April 14, 2009, 04:36:57 PM
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problem:
calculate the mass defect of the nitrogen nucleus 147N.
the mass of the neutral 147N is 14.003074 amu.
what i know:
mass defect=difference in mass between the nucleus of an atom and the sum of the separated particles that make up that nucleus.
mass of neutron=1.008665amu
mass of neutral H=1.007825amu
what i did:
14.003074amu - (1.008665amu + 1.007825amu)
=11.98
this is obviously not right, any help will be greatly appreciated!
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Dear mandy9008;
What is the 14 and the 7 in front of N telling you?
And please don’t forget always the units (11.98 of what?) !!!
Good Luck!
ARGOS++
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the 14 is the mass number and the 7 is the atomic number...
and the units are amu
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Dear mandy9008;
But they tell you also: # of nucleons = 14, and: # of Protons = 7, -
- and that’s much more important for your calculation!
Good Luck!
ARGOS++
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okay. so when i solve for the nuclear binding energy(after i solve for the mass defect) i need the number of nucleons(14), but do i need it to solve for mass defect.
i know the answer is .1124amu
so, im not sure how to get to that number, i have tried every combination i can think of
-adding the 2 masses and subtracting from the # of nucleons
-" " # of protons
-adding the 2 masses
-subtracting the 2 masses
i am still stuck!!
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Dear mandy9008;
First: What is # of nucleons minus # of Protons = 7 meaning? It's equal the # of ??
Second: How is mass defect defined?
Third: The mass defect will come out as 0.112356 amu.
Good Luck!
ARGOS++
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got it!!
14-7=7
7(1.008665)+7(1.0078225)-14.003074
=.112356
=.1124
thank you so much!!
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Dear mandy9008;
Correct!
You 're welcome! ─ Soon again.
Good Luck!
ARGOS++