Question

Which of the following has the greatest number of atoms? a) 1.0 mol He b) 0.60 mol H2 c) 20 g Potassium d) 8.5 mL H2O (density of H2O = 1 g/mL) e) 22.6 g KMnO4

Answer 1

The H2O sample has the greatest number of atoms. 1.41 moles, or (1.041 moles)*(5.023x10^23) atoms

Step-by-step explanation:

We need to convert each value into moles, a count of the number of atoms/molecules.

a) 1.0 moles He

b) 0.60 moles H2

c) 20 grams K: convert to moles with the molar mass of K

(20 grams K)/(39.1 g/mole K) = 0.511 moles K

d) 8.5 mL H2O (density of H2O = 1 g/mL).

Find the mass of the H2): (8.5 ml)*(1 g/ml) = 8.5 grams H2)

Now calculate moles H2): (8.5 grams)/(18 grams/mole) = 0.473 moles H2O

e) 22.6 g KMnO4

(22.6 g KMnO4 )*(158.0 g/mole) = 0.143 moles

Now we need to take into account the number of atoms per molecule:

Molecule Atoms/Molecule Moles Atoms(moles)

He 1 1.0 1.0

H2 2 0.60 1.2

K 1 0.51 0.51

H2O 3 0.47 1.41

KMnO4 6 0.143 0.86

The H2O sample has the greatest number of atoms. 1.41 moles, or (1.041 moles)*(5.023x10^23) atoms