Question

1. how many cu atoms are there in 7.55 g cu?

cu=63.55g
7.55×2 +63.55=78.65g cu
(\frac{7.55}{63.55} = 0.118) g

Explanation:

Step1: Calculate moles of Cu

Moles = $\frac{\text{Mass}}{\text{Molar Mass}}$. Molar mass of Cu is 63.55 g/mol, mass is 7.55 g.
Moles = $\frac{7.55}{63.55} \approx 0.1188$ mol.

Step2: Calculate number of atoms

Use Avogadro's number ($6.022 \times 10^{23}$ atoms/mol).
Atoms = Moles $\times$ Avogadro's number = $0.1188 \times 6.022 \times 10^{23} \approx 7.15 \times 10^{22}$ atoms.

Answer:

Approximately $7.15 \times 10^{22}$ Cu atoms.