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 be $2.363\times 10^{22} atoms$ .

8 0

3 years ago

WITCH IS MADE BY WEATHERING ASH SEDEMENTS MAGMA OR MINERALS

algol [13]

Magma is made from sediments

8 0

3 years ago

When magnesium is ignited in air, the magnesium reacts with oxygen and nitrogen.

vampirchik [111]

51: The only coefficient is in the first one i think and it would be a 3
52: Neon (Ne)
53: Mg has a low nuclear charge so all it's electrons would be lost in the electron shell, making the ion smaller than the atom.

8 0

2 years ago

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