How many molecules of aspirin (formula mass aspirin = 180.0 amu)are there in a 0.250-gram sample?
A)6.02 × $10 ^ { 23 }$
B)8.36 × $10 ^ { 20 }$
C)1.51 × $10 ^ { 23 }$
D)More information is needed.

Question

Quizplus · Accepted Answer

To find the number of molecules in a 0.250-gram sample of aspirin, we first calculate the number of moles of aspirin using its formula mass (180.0 amu, which is equivalent to 180.0 g/mol for molar mass). The number of moles is given by the mass of the sample divided by the molar mass of aspirin: $0.250 \, \text{grams} \div 180.0 \, \text{g/mol} = 0.001389 \, \text{moles}$. Then, we use Avogadro's number ($6.02 \times 10^{23}$ molecules/mol) to find the number of molecules: $0.001389 \, \text{moles} \times 6.02 \times 10^{23} \, \text{molecules/mol} = 8.36 \times 10^{20}$ molecules.

How Many Molecules of Aspirin (Formula Mass Aspirin = 180 102310 ^ { 23 }1023

How Many Molecules of Aspirin (Formula Mass Aspirin = 180 $10 ^ { 23 }$