Question

convert 25 g of mgcl₂ to atoms.

Explanation:

Step1: Calculate molar mass of MgCl₂

The molar mass of Mg is 24.31 g/mol, and Cl is 35.45 g/mol. For MgCl₂, molar mass $M=(24.31 + 2\times35.45)$ g/mol = 95.21 g/mol.

Step2: Calculate number of moles of MgCl₂

Number of moles $n=\frac{m}{M}$, where $m = 25$ g. So $n=\frac{25}{95.21}$ mol $\approx0.263$ mol.

Step3: Calculate number of formula - units of MgCl₂

Using Avogadro's number $N_A = 6.022\times10^{23}$ formula - units/mol. The number of formula - units of MgCl₂, $N=n\times N_A=0.263\times6.022\times10^{23}$ formula - units $\approx1.584\times10^{23}$ formula - units.

Step4: Calculate number of atoms

In one formula - unit of MgCl₂, there are 3 atoms (1 Mg and 2 Cl). So the number of atoms $=3\times N = 3\times1.584\times10^{23}=4.752\times10^{23}$ atoms.

Answer:

$4.752\times10^{23}$ atoms