Topic 5 Flashcards
Physical changes
reversible
Chemical changes
irreversible, form new substance
occur when matter interacts with heat, light, electricity or when two or more different kinds of matter interact
What is thermal decomposition
substance is broken down into two or more simpler substances by the effect of heat
What is combustion
substance and oxygen come in the presence of heat, releasing a lot of energy
What is oxidisation
substance reacting to oxygen
What are acids
substances which produce hydrogen ions in aqueous solution. The hydrogen ions are responsible for the acidic properties
Formula for hydrochloric acid
HCl
Formula for Nitric acid
HNO₃
Formula for Sulfuric acid
H₂SO₄
How do acids taste
sour
Formula for Phosphoric acid
H3PO4
Effect of acids on blue litmus paper and red litmus paper
blue litmus paper turns red
no effect of red litmus
Effect of acids on universal indicator
Indicator turns from green to yellow/orange/red
Do acids conduct electricity
good conductors of electricity in aqueous solution because of mobile ions
Why are acids not acidic in organic solvents
there are no hydrogen ions present
What is formed when acids react with metals
salt + hydrogen
what is formed when dilute hydrochloric acid reacts with metal
metal chloride
What if formed when acids react with metal carbonate
salt + water + carbon dioxide
what is formed when acids react with bases
salt + water
What is the nature of hydrogen gas
colourless, odourless
What is the nature of carbon dioxide gas
colourless, odourless
What is the nature of ammonia gas
colourless, pungent
Test for hydrogen gas
place lighted splint at the mouth of test tube
observe if splint is extinguished with “pop” sound
Test for carbon dioxide gas
Bubble gas into limewater(aqueous cacium hydroxide)
Observe if gas forms white precipitate
