Question

Question #8aff5

Answer 1

There are 1.13 ×10²³ N atoms in 1.00 g of N₂H₄.

Step1. Calculate the moles of N₂H₄.

The molar mass of N₂H₄ is 32.05 g/mol (2×14 + 4×1 = 32).

Then `"1.00 g N"_2"H"_4 × ("1 mol N"_2"H"_4)/("32.05 g N"_2"H"_4) = "0.031 20 mol N"_2"H"_4` ( 3 significant figures + 1 guard digit)

Step 2. Calculate the number of molecules of N₂H₄

You know that 1 mol of molecules contains 6.022 × 10²³ molecules.

So `"0.031 20 mol N"_2"H"_4 × (6.022 × 10^23 "molecules N"_2"H"_4)/("1 mol N"_2"H"_4)` = 1.879 × 10²² molecules N₂H₄.

Step 3. Calculate the number of atoms

1 molecule of N₂H₄ contains 6 atoms (2 of N and 4 of H).

Then `1.879 × 10^22"molecules N"_2"H"_4 × "6 atoms"/("1 molecule N"_2"H"_4)` = 1.13 × 10²³ atoms.