Acid or Base Oxide?
Metal oxides and non-metal oxides behave oppositely.
What this lesson covers
Why it matters
Burn a metal and you get an oxide that behaves like a base. Burn a non-metal and you get an oxide that behaves like an acid. The same word oxide, but opposite personalities.
Predict first
Magnesium oxide (from a metal) and carbon dioxide (from a non-metal) are both oxides. How do they behave with litmus?
Metal oxides are basic (they turn red litmus blue) while non-metal oxides are acidic (they turn blue litmus red).
- Both are acidic and turn blue litmus red
- The metal oxide is basic and the non-metal oxide is acidic — correct
- Both are basic and turn red litmus blue
- Neither has any effect on litmus
What you do
Sort each oxide by whether it comes from a metal (basic oxide) or a non-metal (acidic oxide).
Check yourself
How does a basic oxide such as magnesium oxide affect litmus?
Metal oxides are basic. When dissolved they turn red litmus blue, just like other bases.
Why are oxides of non-metals called acidic oxides?
Non-metal oxides are acidic. They turn blue litmus red and dissolve in water to make acids.
How is sulphur dioxide (SO₂), an acidic oxide, linked to acid rain?
Acidic oxides like sulphur dioxide dissolve in rain water to form acids, which is how acid rain is produced.
- It turns red litmus blue — correct
- It turns blue litmus red
- It has no effect on litmus
- It turns litmus green
- They turn blue litmus red and form acids with water — correct
- They turn red litmus blue
- They are always solids that do not dissolve
- They contain a metal
- It dissolves in rain water to form an acid, making the rain acidic — correct
- It makes rain water alkaline and safe
- It has no effect because gases cannot dissolve in rain
- It turns rain into pure water