1. The electrolysis of water is used to generate 0. 500 g of H2 (g)
The electrolysis of water is used to generate g of H2 (g). If the hydrogen was generated at a rate of amps over a period of 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 x electrons in a coulomb.
It takes 1 electron to make 1 H atom h
x 60 min
x 60 s
x coul
x x el
x 1 at H
1 el
1 h
1 min s
1 coul
= x at H
= x at H g

2. 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

3. Now for the hard part
Lets get ready to rumble!

4. 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, 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 = mole C x g = g C
44.0 g mole CO2 1 mole
1.15 g H2O x 1 mole x 2 mole H = mole H x g = g H
18.02 g mole H2O mole
0.450 g N2 x 1 mole x 2 mole N = mole N x g = g N
28.0 g mole N mole
3.07 g SO2 x 1 mole x 1 mole S = mole S x g = g S
64.1 g mole SO2 1 mole
= moles O
Mass of C H N S = g
Mass of O = Total C H N S O – Mass of C H N S
Mass of O = g –
Mass of O = g
x 1 mole
= moles O
16.0 g

5. Empirical Formula or Mole Ratio
mole C
= 6
x 2 = 12
moles
mole H
= 4
x 2 = 8
moles
mole N
= 1
x 2 = 2
moles
mole S
= 1.5
x 2 = 3
moles
moles O
= 2
x 2 = 4
moles
Empirical Formula C12H8N2O4S3