11.2 What Are The Different Types Of Chemical Changes Flashcards
Combustion
(Textbook) Chemical reaction in which a substance is heated in the presence of oxygen to form one or more new substances. Heat and light are sometimes given out
Carbon + oxygen -> carbon dioxide
(Copied) chemical process in which a substance reacts rapidly with oxygen and gives off heat
Thermal decomposition
Substance breaks down into two or more simpler substances upon heating
Calcium carbonate -heat-> calcium oxide + carbon dioxide
Oxidation under rusting
Process (chemical reaction) when iron reacts with (combines?) oxygen and water (i.e. water vapour in the air) to form rust (reddish-brown flaky solid)
Oxidation under Cellular respiration
Food molecules such as molecules and glucose are broken down in the presence of oxygen to provide cells with energy to survive and reproduce
Glucose + oxygen -> carbon dioxide + water
Neutralisation
Th reaction in which an acid reacts with an alkali to form salt and water
acid+alkali -> salt+water
Characteristics of acids
- sour taste
- corrosive, may burn skin
- turn blue litmus paper red
- e.g. in labs: hydrochloride acid, sulfuric acid, nitric acid
- e.g. @ home: acetic acid (vinegar), ascorbic acid (vitamin c), citric acid (citrus fruits)
Characteristics of Alkalis
- bitter taste
- soapy feel
- corrosive
- turns red litmus paper blue
- e.g. in labs: sodium hydroxide, calcium hydroxide, potassium hydroxide
- e.g. @ home: sodium hydroxide, ammonia, baking soda
Chemical reaction between acids and metals
Acid + metal -> salt + hydrogen
How to test for hydrogen gas produced (and what cannot react with acid to form hydrogen gas)
Use a lighted splint. Hydrogen ‘pops’ with a lighted splint
Copper, silver and gold don’t react with acids
Chemical reactions between acids and carbonates
Acid + carbonate -> salt + carbon dioxide + water
How to test for carbon dioxide gas produced
Use limewater
A white precipitate is formed if carbon dioxide is bubbled into limewater
(CO2 produces a white precipitate)
