1. Nonmetal Oxides
Here we’ll have a closer look at nonmetal oxides, and how they behave in water.

2. Nonmetal Oxides form Acidic Solutions
Metals
Nonmetals
Nonmetal Oxides form Acidic Solutions
Nonmetal Oxides are oxides of elements on the right side of the staircase on the periodic table. Remember, (click) nonmetal oxides react with water to form acidic solutions.

3. O S
SO3
We’ll consider the nonmetal oxide sulphur trioxide, SO3. Nonmetals have electronegativity values closer to that of oxygen than metals have.

4. O S
not an ionic solid
So nonmetal oxides are not ionic solids like metal oxides are.

5. O S
Covalent Bonds
Instead the atoms are joined by covalent bonds, where electrons are shared.

6. O O S O H O S O H H O H
At room temperature, SO3 is a liquid. When it dissolves in water,

7. O O O H O S O H S H O O O H
It reacts with water, and through a series of reactions,

8. O O O H H O S O H S H O O O
Forms sulphuric acid, H2SO4. The Lewis structure for sulphuric acid is shown here. If you check, you will see that sulphur, oxygen, and hydrogen atoms are conserved in this reaction.

9. O S H O H
When H2SO4 is in water, (click) a molecule of H2SO4 will collide with a water molecule and donate a proton to it,

10. – O S H + H O
forming a hydrogen sulphate ion and a hydronium ion.

11. Makes the Solution Acidic– O
Makes the Solution Acidic + H O S O H O O
Because hydronium ions are present, the solution will be acidic.

12. Equations for Nonmetal Oxides
Now we’ll look at a few equations we can write for nonmetal oxides reacting with water.

13. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
When we are considering the reactions of nonmetal oxides with water, we usually stick to writing formula equations for these reactions. We’ll look at some of the common ones here.

14. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
The formula equation summarizing the example we just went over is sulphur trioxide or SO3 reacts with water to produce H2SO4, sulphuric acid. Sulphuric acid is a strong acid.

15. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
The other common oxide of sulphur, sulphur dioxide, SO2, reacts with water to produce H2SO3, or sulphurous acid. Sulphurous acid is a weak acid.

16. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
A common oxide of nitrogen is nitrogen dioxide, NO2. This reacts with

17. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
Water to produce both

18. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
Nitric acid, HNO3, which is a strong acid,

19. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
And nitrous acid, HNO2, which is a weak acid.

20. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
An oxide of the nonmetal chlorine, Dichlorine monoxide, Cl2O, reacts with water to produce the weak acid HOCl, hypochlorous acid. This is an equilibrium reaction. Oxides of the other halogens have similar reactions with water.

21. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
One of the common oxides of phosphorus, P4O6, reacts with water to produce the weak acid H3PO3, phosphorous acid

22. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
Another oxide of phosphorus, P4O10, reacts with water to produce the weak acid H3PO4, phosphoric acid

23. Formula Equations for Reactions of Nonmetal Oxides with Water
sulphuric acid
sulphurous acid
nitric acid
nitrous acid
hypochlorous acid
phosphorous acid
phosphoric acid
You should be familiar with these reactions, especially the reactions for the oxides of sulphur and nitrogen.

24. Acidic Anhydrides Nonmetal Oxides Are also Called
You should also know that nonmetal oxides (click) are also called (click) acidic anhydrides.

25. Acid Anhydrides Nonmetal Oxides Are also Called
Or simply “acid anhydrides”. It’s important to remember that nonmetal oxides, or acid anhydrides react with water to produce acidic solutions.