The atomic masses of the two stable isotopes of copper 63cu29 (69.17 percent) and 65cu29 (30.83 percent)â are 62.929599 and 64.927793 amu, respectively. calculate the average atomic mass of copper.

Average atomic mass of copper is 63.545642 amu

Explanation:

100 atoms of copper contains 69.17 number of atoms and 30.83 number of atoms.

Therefore average atomic mass of copper is given by-

=

=63.545642 amu

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g