Question

What is the mass, in grams, of 1.20×1021 molecules of aspirin, c9h8o4?

Answer 1

Answer: The mass of given number of molecules of aspirin is 0.359 grams.

Explanation:

We are given:

Number of molecules of aspirin = $1.20\times 10^{21}$

We know that:

Molar mass of aspirin $(C_9H_8O_4)$ = 180.16 g/mol

According to mole concept:

$6.022\times 10^{23}$ number of molecules are contained in 1 mole of a compound

Also, $6.022\times 10^{23}$ number of molecules of aspirin has a mass of 180.16 grams

So, $1.20\times 10^{21}$ number of molecules will have a mass of $\frac{180.16}{6.022\times 10^{23}}\times 1.20\times 10^{21}=0.359g$

Hence, the mass of given number of molecules of aspirin is 0.359 grams.

Answer 2

The mass in grams of 1.20 x10^21 molecules of asprin is 0.359 grams

calculation

find the number of moles of aspirin by use of Avogadro's law that is 1 mole =6.02 x10^23 molecules

   what of 1 .20 x10^21  molecules

= (1 mole  x 1.20 x10 ^21 molecules)/6.02 x10^23 molecules)= 1.993 x10^-3 moles

mass of aspirin= moles x molar mass

molar mass of aspirin = (12 x9)+(1 x8) +(16x4)=180 g/mol

mass= 1.993 x10^-3 moles x180 g/mol = 0.359 grams