* Hydrogen is an element: It exists as individual atoms (H), but also forms molecules like diatomic hydrogen (H₂), and compounds like water (H₂O).
* Mass and number of atoms: The mass of a substance depends on the number of atoms *and* the type of atoms present.
Here's how to approach this problem:
1. Specify the substance: Are you asking about pure hydrogen (H₂), water (H₂O), or something else?
2. Calculate moles: Use the molar mass of the substance to convert 1 kg to moles.
* For example, the molar mass of H₂ is 2 g/mol. So, 1 kg (1000 g) of H₂ is 1000 g / 2 g/mol = 500 moles.
3. Use Avogadro's number: One mole of any substance contains 6.022 x 10²³ particles (atoms, molecules, etc.).
* In our H₂ example, 500 moles of H₂ contain 500 moles * 6.022 x 10²³ molecules/mol = 3.011 x 10²⁶ molecules of H₂.
4. Account for hydrogen atoms per molecule: Since each H₂ molecule has two hydrogen atoms, multiply the number of molecules by 2: 3.011 x 10²⁶ molecules * 2 atoms/molecule = 6.022 x 10²⁶ hydrogen atoms.
In summary:
* For 1 kg of pure hydrogen (H₂): There are approximately 6.022 x 10²⁶ hydrogen atoms.
* For other substances: The number of hydrogen atoms will be different depending on the chemical formula and molar mass of the substance.
