Q2Q - Mass Defect (2 Viewers)

[sitk]

For anyone who still isn't sure, I typed up a solution -



Hope that helps. You have to have the electrons. If the question said 12 is mass of carbon NUCLEUS then there are no electrons. But it said it was the mass of the carbon ATOM, therefore electrons must be included.

Btw, does anyone remeber what they got for the binding energy? I think I got 90.5 MeV, I didn't get time to check.

 

[sxgl]

How many people managed to get it to be 0.097?

We were taught to exclude the electrons, thus we (whole cohort) could only show it was equal to 0.094. I'd imagine if you included the electrons in the defect however, you would get 0.097amu

How many marks would i expect to lose for not taking into account the electrons?

=. ="

hay i thought i was the only one with that problem... i spent ages on that calculation... i got the same answer! but i did the conversions right and the calculations right.

converts protons and neutrons to amu and dan i times them both by 6 then minus 12.... the answer i got was 0.0937....... =[

OH SH!T now i know what i did wrong!!!! I FORGOT THE ELECTRONS!!!!! AHH STUPID ME!!! one more reason to be angry about that test..

 

[glockenspiel]

Ah damn I said there were 12 electrons lol. What a dumb mistake.

 

[sxgl]

Ah damn I said there were 12 electrons lol. What a dumb mistake.

well is wouldnt be as bad as EXCLUDING the electron.... dat question got me wondering for ages... i thought there was a mistake in the paper AHAHAHAHA

 

[sweetgal]

yeah. it asked for ATOM and not nucleus. 'ATOM' includes the electrons. i got 0.0969 or sth.

 

[sxgl]

yeah. it asked for ATOM and not nucleus. 'ATOM' includes the electrons. i got 0.0969 or sth.

it didnt hit me till i got home... i even answered a question on mass defect before entering the exam room cause my teacher asked me... o wells... i stuffed up the test and thats all i need to say.

 

[patv]

For anyone who still isn't sure, I typed up a solution -



Hope that helps. You have to have the electrons. If the question said 12 is mass of carbon NUCLEUS then there are no electrons. But it said it was the mass of the carbon ATOM, therefore electrons must be included.

Btw, does anyone remeber what they got for the binding energy? I think I got 90.5 MeV, I didn't get time to check.

yeah for binding energy, i got around 90s. you just multiplied your mass defect by 931.5 right?