The electrolysis of water is used to generate 0. 500 g of H2 (g) The electrolysis of water is used to generate 0.500 g of H2 (g). If the hydrogen was generated at a rate of 3.000 amps over a period of 4.46625 hours, calculate Avogadro’s number (the number of atoms of H in 1 gram) 1 amp is defined as the number of coulombs per second. There are 6.24 x 1018 electrons in a coulomb. It takes 1 electron to make 1 H atom 4.46625 h x 60 min x 60 s x 3.000 coul x 6.24 x 1018 el x 1 at H 1 el 1 h 1 min s 1 coul = 3.01 x 1023 at H = 6.02 x 1023 at H 0.5000 g

C N O S H C H N S O We have a chemical compound Need to determine the empirical formula 5.43 g We burn the compound in O2 and measure the amount of CO2, H20, N2, and SO2 produced. minus From the mass of CO2 we can calculate moles of C and grams From the mass of H2O we can calculate moles of H and grams moles moles moles moles C H N S From the mass of N2 we can calculate moles of N and grams From the mass of SO2 we can calculate moles of S and grams g g g g =Total g = moles O How do we get moles of O ? = g

Now for the hard part Lets get ready to rumble!

A compound was known to contain C, H, N, O, and S. When a 5 A compound was known to contain C, H, N, O, and S. When a 5.43 g sample was burned the products were 8.43 g CO2, 1.15 g H2O, 0.450 g N2, and 3.07 g of SO2. Determine the empirical formula of the compound. 8.43 g CO2 x 1 mole x 1 mole C = 0.1916 mole C x 12.0 g = 2.299 g C 44.0 g 1 mole CO2 1 mole 1.15 g H2O x 1 mole x 2 mole H = 0.1276 mole H x 1.01 g = 0.1289 g H 18.02 g 1 mole H2O 1 mole 0.450 g N2 x 1 mole x 2 mole N = 0.03214 mole N x 14.0 g = 0.4500 g N 28.0 g 1 mole N2 1 mole 3.07 g SO2 x 1 mole x 1 mole S = 0.04789 mole S x 32.1 g = 1.537 g S 64.1 g 1 mole SO2 1 mole = 0.06344 moles O Mass of C H N S = 4.4149 g Mass of O = Total C H N S O – Mass of C H N S Mass of O = 5.43 g – 4.4149 Mass of O = 1.0151 g x 1 mole = 0.06344 moles O 16.0 g

Empirical Formula or Mole Ratio 0.1916 mole C = 6 x 2 = 12 0.03214 moles 0.1276 mole H = 4 x 2 = 8 0.03214 moles 0.03214 mole N = 1 x 2 = 2 0.03214 moles 0.04779 mole S = 1.5 x 2 = 3 0.03214 moles 0.06344 moles O = 2 x 2 = 4 0.03214 moles Empirical Formula C12H8N2O4S3