Question

consider a sample containing 0.320 mol of a substance. how many atoms are in the sample if the substance is lead? lead: atoms how many atoms are in the sample if the substance is gold? gold: atoms how many molecules are present in the sample if the substance is benzene, c₆h₆? c₆h₆: molecules

Explanation:

Step1: Recall Avogadro's number

Avogadro's number $N_A = 6.022\times 10^{23}\text{ mol}^{-1}$.

Step2: Calculate number of atoms/molecules for lead

For lead (a mon - atomic substance), the number of atoms $N=n\times N_A$, where $n = 0.320\text{ mol}$. So $N=0.320\text{ mol}\times6.022\times 10^{23}\text{ mol}^{-1}=1.93\times 10^{23}$ atoms.

Step3: Calculate number of atoms/molecules for gold

Gold is also a mon - atomic substance. Using $N=n\times N_A$ with $n = 0.320\text{ mol}$, we get $N=0.320\text{ mol}\times6.022\times 10^{23}\text{ mol}^{-1}=1.93\times 10^{23}$ atoms.

Step4: Calculate number of atoms/molecules for benzene

Benzene ($C_6H_6$) is a molecular substance. Using $N=n\times N_A$ with $n = 0.320\text{ mol}$, we have $N=0.320\text{ mol}\times6.022\times 10^{23}\text{ mol}^{-1}=1.93\times 10^{23}$ molecules.

Answer:

lead: $1.93\times10^{23}$ atoms
gold: $1.93\times10^{23}$ atoms
$C_6H_6$: $1.93\times10^{23}$ molecules