Question

1. how many moles of be are there in a sample that contains 3.27×10^22 beryllium atoms? use the references to access important values if needed for this question. 2. how many beryllium atoms are there in a sample that contains 3.05 mol of be? 3 item attempts remaining

Explanation:

Step1: Recall Avogadro's number

Avogadro's number ($N_A$) is $6.022\times 10^{23}$ atoms/mol.

Step2: Calculate moles in first - part

To find the number of moles when the number of atoms is given, use the formula $n=\frac{N}{N_A}$, where $n$ is the number of moles, $N$ is the number of atoms. Given $N = 3.27\times 10^{22}$ atoms of Be. Then $n=\frac{3.27\times 10^{22}}{6.022\times 10^{23}}$ mol.
$n=\frac{3.27}{60.22}\approx0.0543$ mol.

Step3: Calculate number of atoms in second - part

To find the number of atoms when the number of moles is given, use the formula $N = n\times N_A$. Given $n = 3.05$ mol of Be. Then $N=3.05\times6.022\times 10^{23}$ atoms.
$N = 3.05\times6.022\times 10^{23}=1.83671\times 10^{24}$ atoms.

Answer:

1. $0.0543$ mol
2. $1.84\times 10^{24}$ atoms