How many hydrogen atoms are in the following?

Question

44.8 L of hydrogen at STP
divide 44.8 by 22.4 and then thats the answer
11.2 L of hyrogen sulfide at STP
divide 11.2 by 22.4 and then subtract teh molar mass of Sulfur????

5.6 L of hydrogen chloride at STP
divide by 22.4 and then subtract teh molar mass of Chloride

200 L of Water with with density at room temp 0.9998 gm/mL
0.9998 times 1000 to become liters. divide 200L by 22.4 and figure it out???

Answer 1

For 1-3:
Divide by 22.4, then multiply by the number of moles of Hydrogen in the molecule, and then multiply by Avogadro's Number. Don't worry about the other atoms in the molecule - they're irrelevant.

So, for Hydrogen Gas (H2):
44.8 / 22.4 = 2
2 * 2 (# of H atoms) = 4
4 * 6.02214 * 10^23 = 2.4089 * 10^24 atoms

Note: You can only use the 22.4 rule if it is a gas, and the gas is at STP.

4.) Since this is a liquid, you do not use 22.4 (that's only for gasses).
D = 999.8 g/L * 200 L = 199960 g

Divide the mass by the molar mass of water (2*1 + 16 = 18 g/mol), then multiply by the # of moles of Hydrogen:
199960 / 18 = 11109 moles of Water.
11109 moles of H2O * 2 moles H/mol H2O = 22218 mol H

Multiply the # of moles by Avogadro's #:
22218 mol H * 6.02214 * 10^23 = 1.338 * 10^28 (solution)