Question

How many atoms are in 3.5 grams of copper

Answer 1

Avegadro's number = 6.02 x10^23 atoms
so
3.5g x 1mol/63.55g Cu x 6.02 x 10^23/ 1mol=3.32 x 10^22 atoms

Answer 2

Answer: For the given mass of copper, the number of atoms are $3.3121\times 10^{22}$

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$  

Given mass of copper = 3.5 g

Molar mass of copper = 63.55 g/mol

Putting values in above equation, we get:

$\text{Moles of copper}=\frac{3.5g}{63.55g/mol}=0.055mol$

According to mole concept:

1 mole of an element contains $6.022\times 10^{23}$ number of atoms

So, 0.055 moles of copper will contain = $0.055\times 6.022\times 10^{23}=3.3121\times 10^{22}$ number of atoms.

Hence, for the given mass of copper, the number of atoms are $3.3121\times 10^{22}$