Which of the following samples contains the greatest total number atoms? A)50.0 g of Li ₂O B)75.0 g of CaO C)200.0 g of Fe ₂O ₃ D)50.0 g of CO ₂ E)100.0 g of SO ₃

Question

Quizplus · Accepted Answer

To determine the total number of atoms in each sample, we need to calculate the number of moles of each compound and then use Avogadro's number to convert to the number of atoms.

A) Li2SO4: 
- Calculate the molar mass: 
- Li: 6.94 g/mol 
- S: 32.07 g/mol 
- O: 15.99 g/mol 
- Total molar mass: 86 g/mol 
- Number of moles in 50.0 g: 0.581 mol 
- Total number of atoms: 3.00 x 10^23 x 0.581 = 1.74 x 10^23 atoms

B) CaO: 
- Calculate the molar mass: 
- Ca: 40.08 g/mol 
- O: 15.99 g/mol 
- Total molar mass: 56.07 g/mol 
- Number of moles in 75.0 g: 1.34 mol 
- Total number of atoms: 7.26 x 10^23 x 1.34 = 9.75 x 10^23 atoms

C) FeSO4: 
- Calculate the molar mass: 
- Fe: 55.85 g/mol 
- S: 32.07 g/mol 
- O: 15.99 g/mol 
- Total molar mass: 151.91 g/mol 
- Number of moles in 200.0 g: 1.32 mol 
- Total number of atoms: 6.02 x 10^23 x 1.32 x 26 = 2.01 x 10^25 atoms (note that there are 26 atoms in each FeSO4 molecule)

D) CO: 
- Calculate the molar mass: 
- C: 12.01 g/mol 
- O: 15.99 g/mol 
- Total molar mass: 28.00 g/mol 
- Number of moles in 50.0 g: 1.79 mol 
- Total number of atoms: 6.02 x 10^23 x 1.79 x 2 = 2.04 x 10^24 atoms (note that there are 2 atoms in each CO molecule)

E) SO3: 
- Calculate the molar mass: 
- S: 32.07 g/mol 
- O: 15.99 g/mol 
- Total molar mass: 80.06 g/mol 
- Number of moles in 100.0 g: 1.25 mol 
- Total number of atoms: 6.02 x 10^23 x 1.25 x 4 = 3.78 x 10^24 atoms (note that there are 3 atoms in each SO3 molecule)

Therefore, the sample with the greatest total number of atoms is C, with a total of 2.01 x 10^25 atoms.

Which of the Following Samples Contains the Greatest Total Number