## Chemistry: A Molecular Approach (3rd Edition)

$1.241\times10^{24}\ molecules$
Convert the mass of the sample to moles by dividing by the molar mass of the compound. The multiply by Avagadro's number to get the number of molecules (or formula units for ionic compounds as they do not exist as individual molecules. $119.78g\ C_{4}H_{10}\times\frac{1mol\ C_{4}H_{10}}{58.12g\ C_{4}H_{10}}\times\frac{6.022\times10^{23}\ molecules}{1\ mol}= 1.241\times10^{24}\ molecules$