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Romashka [77]
3 years ago
12

How many cu atoms are present in a piece of sterlingsilver jewelry weighing 33.24 g ? (sterling silver is a silver–copper alloy

containing 92.5% ag by mass.)?
Chemistry
1 answer:
emmasim [6.3K]3 years ago
8 0

The mass of piece of sterling silver jewelry is 33.24 g. It contains 92.5% silver Ag by mass. Since, sterling silver is an alloy of Ag-Cu thus, percentage of Cu will be:

% Cu=100-92.5=7.5%

Thus, mass of copper will be:

m_{Cu}=\frac{7.5}{100}\times 33.24 g=2.493 g

Molar mass of Cu is 63.546 g/mol, thus, number of moles of Cu can be calculated as follows:

n=\frac{m}{M}

Here, m is mass and M is molar mass.

Putting the values,

n=\frac{2.493 g}{63.546 g/mol}=0.03923 mol

Now, in 1 mole of Cu there are 6.303\times 10^{23}atoms thus, in 0.03923 mol, number of Cu atoms will be:

0.03923 mol\times 6.303\times 10^{23}atoms=2.363\times 10^{22} atoms

Thus, number of atoms of Cu will be2.363\times 10^{22} atoms.


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