1. Starting with 9.3 moles of O2 , how many moles of H2S will be needed and how many moles of SO2 will
be produced in the following reaction? SHOW YOUR WORK!
2 H2S + 3 O2 -> 2 SO2 + 2 H2O

6.2 moles of H₂S of moles are needed.

6.2 moles of SO₂ are produced.

Explanation:

Reaction: 2 H₂S + 3 O₂  → 2SO₂ + 2H₂O

2 moles of hydrogen sulfide can react to 3 moles of oxygen in order to produce 2 moles of sulfur dioxide and 2 moles of water.

We propose the following rule of three:

If 3 moles of oxygen need 2 moles of H₂S to react

Then, 9.3 moles of O₂ will react with (9.3 . 2) / 3 = 6.2 moles of H₂S

3 moles of O₂ can produce 2 moles of SO₂

So, 9.3 moles will produce (9.3 . 2) / 3 = 6.2 moles of SO₂

If we take account the 6.2 moles of H₂S (the value we obtained), we get the same 6.2 moles of SO₂. This is because ratio is 2:2

"the periodic table is arranged in order of atomic number."