Answer :

To find the number of molecules in 122 grams of copper (Cu), we can follow these steps:

1. Determine the Molar Mass of Copper (Cu):
Copper has a molar mass of approximately 63.546 grams per mole. This means that one mole of copper weighs 63.546 grams.

2. Calculate the Number of Moles of Copper:
To find out how many moles are in 122 grams of copper, you divide the given mass by the molar mass of copper:
[tex]\[
\text{Number of moles} = \frac{\text{Mass in grams}}{\text{Molar mass}} = \frac{122 \text{ grams}}{63.546 \text{ g/mol}}
\][/tex]
This calculation results in approximately 1.92 moles of copper.

3. Use Avogadro's Number to Find the Number of Molecules:
Avogadro's number, which is [tex]\(6.022 \times 10^{23}\)[/tex], represents the number of atoms, ions, or molecules in one mole of a substance.

To find the number of copper molecules, multiply the number of moles by Avogadro's number:
[tex]\[
\text{Number of molecules} = \text{Number of moles} \times 6.022 \times 10^{23}
\][/tex]
Substituting the number of moles we calculated:
[tex]\[
\text{Number of molecules} = 1.92 \times 6.022 \times 10^{23} \approx 1.16 \times 10^{24}
\][/tex]

Therefore, there are approximately [tex]\(1.16 \times 10^{24}\)[/tex] molecules in 122 grams of copper.

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