How many molecules are contained in 25.0 g H2? Solution: (A.wt H= 1.008 g/mole)
To calculate the number of molecules in 25.0 g H2, we need to use the formula:
Number of molecules = (mass of substance / molar mass) * Avogadro's number
First, let's calculate the molar mass of H2. H2 is made up of two hydrogen atoms, so the molar mass is:
Molar mass H2 = 2 * (atomic mass H) = 2 * 1.008 g/mole = 2.016 g/mole
Now, let's substitute the values into the formula:
Number of molecules = (25.0 g / 2.016 g/mole) * 6.022 × 10^23 molecules/mole
Number of molecules = (12.388 mol) * 6.022 × 10^23 molecules/mole
Number of molecules ≈ 7.456 × 10^24 molecules
Therefore, there are approximately 7.456 × 10^24 molecules in 25.0 g H2.