Here are the procedure steps:

Here are the first four problems:

1) Calculate the number of molecules in 1.058 mole of H₂O

2) Calculate the number of atoms in 0.750 mole of Fe

3) Calculate the number of molecules in 1.058 gram of H₂O

4) Calculate the number of atoms in 0.750 gram of Fe

Now the solutions:

1.058 mole x 6.022 x 10²³ molecules/mole

0.750 mole x 6.022 x 10²³ atoms/mole

(1.058 gram divided by 18.0 g/mol) x 6.022 x 10²³ molecules/mole

(0.750 gram divided by 55.85 g/mole) x 6.022 x 10²³atoms/mole

5) Basically, this is just two two-step problems in one sentence. Convert each gram value to its mole equivalent. Then, multiply the mole value by Avogadro's Number. Finally, compare these last two values and pick the larger value. That is the one with more molecules.

6) Ammonia's formula is NH₃ and water's is H₂O. Ammonia has three atoms of H per molecule and water has two atoms of H per molecule.

ammonia's contribution:

8.10 x 10²⁴ times 3 = 2.43 x 10²⁵ H atoms

water's contribution:

2.10 x 10²⁵ times 2 = 4.20 x 10²⁵ H atoms

sum them up:

2.43 x 10²⁵ + 4.20 x 10²⁵ = 6.63 x 10²⁵ H atoms

Return to Avogadro Number Calculations

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