Question

how many moles of cu are present in 8.99 x 10^{25} atoms cu? 4.51 x 10^{49} moles cu 149 moles cu 6.02 x 10^{49} moles cu 0.149 moles cu

Explanation:

Step1: Recall Avogadro's number

Avogadro's number \(N_A = 6.02\times10^{23}\text{ atoms/mol}\). The formula to convert the number of atoms \(N\) to moles \(n\) is \(n=\frac{N}{N_A}\).

Step2: Substitute the values

Given \(N = 8.99\times 10^{25}\text{ atoms}\) and \(N_A=6.02\times 10^{23}\text{ atoms/mol}\). Then \(n=\frac{8.99\times 10^{25}}{6.02\times 10^{23}}\).
Using the rule of exponents \(\frac{a^m}{a^n}=a^{m - n}\), we have \(\frac{8.99}{6.02}\times10^{25-23}\).
\(\frac{8.99}{6.02}\approx1.49\) and \(10^{25 - 23}=10^{2}\). So \(n = 1.49\times10^{2}=149\text{ moles}\).

Answer:

149 moles Cu