Metals burn into bases
A burnt metal makes an oxide, and the oxide is basic.
The vanished ribbon
Magnesium ribbon burns with a dazzling white flame. The shiny ribbon is gone. What is left behind?
After the ribbon has burnt, what do you think is left?
What this lesson covers
The idea
Metals react with oxygen to form metal oxides, which are generally basic in nature.
The vanished ribbon
Magnesium ribbon burns with a dazzling white flame. The shiny ribbon is gone. What is left behind?
After the ribbon has burnt, what do you think is left?
- A white powder
- Nothing at all
- A shiny new ribbon
Burn, dissolve, test
Press the three buttons in order: burn the ribbon, put the powder in water, then dip red litmus paper.
Metal oxides
Metals react with oxygen to form metal oxides. Magnesium and the oxygen in the air make magnesium oxide. Metal oxides are generally basic in nature.
A base turns red litmus paper blue. The magnesium oxide solution does exactly that, so it is basic.
- Stage | What we see
- Magnesium burns in air | dazzling white flame
- What is left | white powder: magnesium oxide
- Solution of the powder | turns red litmus paper blue
Notes
Metals react with oxygen to form metal oxides, which are generally basic. Magnesium burns to white magnesium oxide, and its solution turns red litmus blue.
Check yourself
The white powder left after burning magnesium is called...
Magnesium oxide is formed from magnesium and...
The solution of magnesium oxide changes red litmus paper to blue. So it is...
Generally, oxides of metals are...
- magnesium oxide — correct. Yes! Magnesium joined with oxygen from the air.
- magnesium ribbon. The ribbon is what we started with.
- sulfur dioxide. That is made by burning sulfur.
- water. Burning needs oxygen from the air.
- oxygen from the air — correct. Yes!
- kerosene. Burning magnesium takes oxygen from the air.
- acidic. An acid turns blue litmus red.
- basic — correct. Yes! A base turns red litmus blue.
- neutral. A neutral solution changes neither colour.
- basic in nature — correct. Yes!
- acidic in nature. Oxides of non-metals are acidic. Metal oxides are basic.
- neutral in nature. Metal oxides are generally basic.