Question

hi please help with this question! Need the workings.

A copper penny has a mass of 2.6 g Assuming it is pure copper, how much of this mass is contributed by a) the neutrons in the copper nuclei b) the electrons.


The answers are
a) 1.41 g
b) 6.5 x 10^-4

Answer 1

first you have to calculate no. of moles 2.6 g copper have
since 1 mole have Avogadro no. of atoms
u can find no. of atoms 2.6 g cu have
i think from here you can do it.

Answer 2

Cu atoms/mole of Cu = 6.040 x 10^23 copper atoms/mole of copper
2.6 g / 63.058 g/mole = 0.04123 moles of Cu

0.04123 mol * 6.040 x 10^23 copper atoms/mole of copper =
= 2.490292 * 10^22 copper atoms in 2.6 grams
There are 29 electrons per copper atom

Mass of 1 electron=9.085*10^(-28) gram
Mass of 2.6 gm of Cu electrons =(9.085*10^(-28) g)(29)(2.490292 * 10^22)

answer: = 6.561 * 10^-4
---------------------------

Answer 3

Copper has a normal atomic mass of 63.546
It's atomic number is 29.
It's atomic mass is 63 disregarding other mass in the atom
Atomic mass -Atomic number = neutrons mass

29 - 63 = 34

Neutron weight is 34 ,

a ) answer: 2.6 g of copper * (34 / 63) = 1.4 gram for neutron weight -----------------------------

Answer 4

I gave the work for answers a) and b) above.

Check the work out yourself

Answer 5

thank you!!