1. Find the molar mass of ammonia:
* Nitrogen (N) has a molar mass of 14.01 g/mol.
* Hydrogen (H) has a molar mass of 1.01 g/mol.
* Ammonia (NH₃) has a molar mass of 14.01 g/mol + (3 * 1.01 g/mol) = 17.04 g/mol
2. Convert grams of ammonia to moles:
* Moles = (mass in grams) / (molar mass)
* Moles = 0.75 g / 17.04 g/mol = 0.044 mol
3. Use Avogadro's number to convert moles to molecules:
* Avogadro's number is 6.022 x 10²³ molecules/mol
* Number of molecules = (moles) * (Avogadro's number)
* Number of molecules = 0.044 mol * 6.022 x 10²³ molecules/mol
* Number of molecules = 2.65 x 10²² molecules
Therefore, there are approximately 2.65 x 10²² molecules in 0.75 grams of ammonia.
